Some bacteria have the ability to co-exist, proliferate and survive in a multicellular community, biofilm. Each participating bacteria can form its colonies and encases itself by a self-produced insoluble extracellula...Some bacteria have the ability to co-exist, proliferate and survive in a multicellular community, biofilm. Each participating bacteria can form its colonies and encases itself by a self-produced insoluble extracellular matrix substance (EPS). Microcolonies within biofilm are held together by interactions and bonding of the substances present in the EPS with their separation from the water channels. Similar to insoluble EPS, bacterial microcolonies release soluble exofactors that have direct impacts on the survivability, growth and antibacterial resistivity of other microcolonies made of single- or multi-species bacteria in the same biofilm. How the exofactors of microcolonies of one-type bacteria impact on microcolonies of other-type bacteria is still unclear. We studied about the role of exofactors released from Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa, which are common biofilm-forming pathogenic bacteria. Exofactors facilitate to transform the microenvironment where bacteria can acquire alternative lifestyle with a long survival period and resistivity to certain antimicrobial drugs.展开更多
Vine decline disease (VDD) constitutes a menace to melons worldwide. Especially, the one caused by the fungus Monosporascus cannonballus. Thus, resistant plant material must be released to help growers. Hence, our goa...Vine decline disease (VDD) constitutes a menace to melons worldwide. Especially, the one caused by the fungus Monosporascus cannonballus. Thus, resistant plant material must be released to help growers. Hence, our goal was to develop resistant plant material to VDD. More than 600 melon accessions are expected to be tested for disease resistance in M. cannonballus infested soil in Weslaco, Texas, USA, to identify resistance to VDD, and other important traits. So far, at most 7 lines were found to be resistant to VDD and some of them were used to develop elite, muskmelon inbred lines by pedigree breeding following single or double backcrosses. These elite parents were crossed to each other to develop the hybrids M3 and M4. They were also tested in the same infested field in Weslaco. The hybrids were grown using standard commercial practices followed by growers and when their fruits were ready, their roots were sampled as well as scored for disease severity to estimate high and mid-parent heterosis Our results indicate the existence of heterosis regarding resistance to VDD. Thus, resistant plant material can be developed and selection for resistance can be accomplished.展开更多
The continued decline in the availability of water from the Ogallala Aquifer in the Texas Panhandle has led to an increased interest in conservation policies designed to extend the life of the aquifer and sustain rura...The continued decline in the availability of water from the Ogallala Aquifer in the Texas Panhandle has led to an increased interest in conservation policies designed to extend the life of the aquifer and sustain rural economies. Four counties were chosen for evaluation. This study evaluates the effectiveness of five policies in terms of changes in the saturated thickness, crop mix, water use per acre, and the net present value of farm profits over a 60-year planning horizon. The dynamic optimization models were developed using GAMS for the baseline as well as one for all five of the policy alternatives for each county. Results indicate that the policy scenarios of biotechnology adoption and a water use restriction will conserve the most water among the policies analyzed. In terms of economic returns, the biotechnology adoption policy by far provides the greatest benefit to producers due to yield increases that are estimated with current annual growth rates in new seed varieties. The water use restriction policy, on the other hand, has the lowest net present value of returns, indicating that conservation is accompanied with significant costs to producers. The irrigation adoption technology scenario is the next best policy in terms of net present value of returns (following biotechnology);however, it ranks last in terms of reducing aquifer depletion. It is important to note that while the models do not perfectly predict the factors being evaluated, it is the basis for comparison between the policy scenarios which are important. These comparisons will aid policy makers in determining the most effective strategy to conserve water while simultaneously considering the economic costs to producers. In addition, the results of this study can be applied to other areas facing similar conditions, either currently or in the future, throughout the Texas Panhandle.展开更多
Hydrologic and water quality models are often used in assessing the response of environmental processes to human activities and climatic change. However, these models differ in terms of their complexity, requirements,...Hydrologic and water quality models are often used in assessing the response of environmental processes to human activities and climatic change. However, these models differ in terms of their complexity, requirements, underlying equations, and assumptions, and as such their performance in simulating landscape processes varies. Consequently, a key question that has to be addressed is to select the most suitable model that gives results closest to reality for an intended purpose. In this study, the performance of the basin-wide older version of SWAT is compared with that of the small watershed model APEX to assess the performance of both models at a field scale level. The new restructured version of SWAT (SWAT+) is compared with the older version to determine whether the new changes incorporated in SWAT+ have improved model performance, particularly for small watersheds. The three models were used to simulate the edge of field processes for a 6.6 ha plot located at the USDA-Agricultural Research Station near Riesel, Texas, and to predict water yield, soil, and mineral phosphorous loss from the micro watershed. Results showed that all the uncalibrated models over-predict soil and phosphorous loss in a micro watershed. Uncalibrated SWAT and SWAT+ models simulated water yield satisfactory albeit with low-performance metrics. The calibrated versions simulated water yield with indices close to optimal values. PBIAS as a performance assessment metric was determined to be overly sensitive and prone to numerical errors. SWAT+ will be helpful in the understanding of hydrological and water quality processes at micro watersheds considering that it addresses structural flaws associated with the older version, and the manually calibrated version matches the performance of both APEX and SWAT, despite the latter two undergoing rigorous automatic calibration.展开更多
Lectins are carbohydrate-binding proteins with agglutination properties. There is a continuous interest in lectins due to their biological properties that can be exploited for medicinal and therapeutic purposes. The o...Lectins are carbohydrate-binding proteins with agglutination properties. There is a continuous interest in lectins due to their biological properties that can be exploited for medicinal and therapeutic purposes. The objective of this study was to isolate and characterize lectin activity in Texas Live Oak (Quercus fusiformis). More specifically, the study aimed to determine the lectin’s blood group specificity and pH stability, determine effects of seasonal variation, soil moisture and soil pH on lectin activity. The study also aimed to determine the presence of antifungal activity in Q. fusiformis extracts. Lectin activity was detected and compared via agglutination and protein assays. Protein partial purification was accomplished using diethylaminoethyl ion-exchange chromatography matrix. High Performance Liquid Chromatography (HPLC) was used to assess purity of the lectin. Results showed that Q. fusiformis extracts’ lectin activities are stable at a pH range of 5.2 - 9.2 but with a significant decrease in activity above pH 9.2. The lectin activity was significantly higher when assayed against sheep red blood cells as compared to other blood groups tested. Quercus fusiformis extract is devoid of antifungal activity against Aspergillus niger and Rhizopus stolonifer. The effects of seasonal variation, soil moisture and soil pH do not significantly correlate with lectin activity. Results from HPLC showed presence of three peaks indicating a partial purification of the Q. fusiformis lectin.展开更多
We analyzed two types of crude oil samples: Middle Eastern crude oil and Texas crude oil by using a residual gas analyzer (RGA) based on the linear quadrupole principle. This portable mass analyzer is capable of measu...We analyzed two types of crude oil samples: Middle Eastern crude oil and Texas crude oil by using a residual gas analyzer (RGA) based on the linear quadrupole principle. This portable mass analyzer is capable of measuring hydrocarbons with masses of up to 300 atomic mass units (amu) as well as low mass targets, such as methane and carbon dioxide at ppm level concentrations. The generated mass spectra revealed differences in the composition and signal intensity of hydrocarbons of Middle Eastern and Texas crude oil samples. Even if RGA 300 is manufactured to be served as a detailed gas analysis of vacuum systems, we have shown that it is sensitively capable of detection of hydrocarbons and it enables one to qualitative and quantitative analysis of the composition of the crude oils.展开更多
Assessment of debris flow hazards is important for developing measures to mitigate the loss of life and property and to minimize environmental damage. Two modified uncertainty models, Set Pair Analysis （SPA） and mod...Assessment of debris flow hazards is important for developing measures to mitigate the loss of life and property and to minimize environmental damage. Two modified uncertainty models, Set Pair Analysis （SPA） and modified Set Pair Analysis （mSPA）, were suggested to assess the regional debris flow hazard. A ease study was conducted in seven towns of the Beichuan county, Sichuan Province, China, to test and compare the application of these two models in debris flow hazard assessment. The results showed that mSPA only can fit for value-variables, but not for non value-variable assessment indexes, Furthermore, as for a given assessment index xi, mSPA only considers two cases, namely, when grade value increases with xi and when grade value decreases with xi. Thus, mSPA can not be used for debris flow hazard assessment but SPA is credible for the assessment because there are no limitations when using SPA model to assess the debris flow hazard. Therefore, in this study SPA is proposed for assessing debris flow hazard.展开更多
The intestinal microbiota is the collection of the living microorganisms(bacteria, fungi, protozoa, and viruses) inhabiting the gastrointestinal tract. Novel bacterial identification approaches have revealed that the ...The intestinal microbiota is the collection of the living microorganisms(bacteria, fungi, protozoa, and viruses) inhabiting the gastrointestinal tract. Novel bacterial identification approaches have revealed that the gastrointestinal microbiota of dogs and cats is, similarly to humans, a highly complex ecosystem. Studies in dogs and cats have demonstrated that acute and chronic gastrointestinal diseases, including inflammatory bowel disease(IBD), are associated with alterations in the small intestinal and fecal microbial communities. Of interest is that these alterations are generally similar to the dysbiosis observed in humans with IBD or animal models of intestinal inflammation, suggesting that microbial responses to inflammatory conditions of the gut are conserved across mammalian host types. Studies have also revealed possible underlying susceptibilities in the innate immune system of dogs and cats with IBD, which further demonstrate the intricate relationship between gut microbiota and host health. Commonly identified microbiome changes in IBD are decreases in bacterial groups within the phyla Firmicutes and Bacteroidetes, and increases within Proteobacteia. Furthermore, a reduction in the diversity of Clostridium clusters XIVa and IV(i.e., Lachnospiraceae and Clostridium coccoides subgroups) are associated with IBD, suggesting that these bacterial groups may play an important role in maintenance of gastrointestinal health. Future studies are warranted to evaluate the functional changes associated with intestinal dysbiosis in dogs and cats.展开更多
A support(denoted AM) was prepared using pseudo-boehmite and mordenite.Ni-B and NiPtB amorphous catalysts were prepared on the support by the impregnation method followed by chemical reduction with a KBH4 solution.And...A support(denoted AM) was prepared using pseudo-boehmite and mordenite.Ni-B and NiPtB amorphous catalysts were prepared on the support by the impregnation method followed by chemical reduction with a KBH4 solution.And the catalysts were characterized by X-ray diffraction(XRD),environment scanning electron microscope(ESEM),inductively coupled plasma(ICP),H2-temperature programmed reduction(H2-TPR),differential thermal analysis(DTA),and BET.Benzene hydrogenation was used as a probe reaction to evaluate the effect of addition of small quantities of Pt on the NiB/AM catalyst.The results show that Pt can promote the reduction of NiO and the formation of active sites,leading to smaller catalyst particles and better dispersion of active metal particles on the support.The catalytic activity,sulfur resistance and thermal stability were remarkably improved by Pt doping of the NiB/AM catalyst.展开更多
A fully coupled thermo-hydro-mechano-chemical（THMC） formulation is described in this paper.Special attention is paid to phenomena likely to be encountered in clay barriers used as engineered barriers in the disposal...A fully coupled thermo-hydro-mechano-chemical（THMC） formulation is described in this paper.Special attention is paid to phenomena likely to be encountered in clay barriers used as engineered barriers in the disposal of nuclear radioactive waste.The types of processes considered in the chemical formulation include hydrolysis,complex formation,oxidation/reduction reactions,acid/base reactions,precipitation/dissolution of minerals and cation exchange.Both kinetics-and equilibrium-controlled reactions are incorporated.The formulation is implemented in a numerical code.An application is presented concerning the performance of a large-scale in-situ heating test simulating high-level radioactive waste repository conditions.展开更多
In this context,two different approaches of soil liquefaction evaluation using a soft computing technique based on the worldwide standard penetration test(SPT) databases have been studied.Gene expression programming(G...In this context,two different approaches of soil liquefaction evaluation using a soft computing technique based on the worldwide standard penetration test(SPT) databases have been studied.Gene expression programming(GEP) as a gray-box modeling approach is used to develop different deterministic models in order to evaluate the occurrence of soil liquefaction in terms of liquefaction field performance indicator(LI) and factor of safety(FS) in logistic regression and classification concepts.The comparative plots illustrate that the classification concept-based models show a better performance than those based on logistic regression.In the probabilistic approach,a calibrated mapping function is developed in the context of Bayes’ theorem in order to capture the failure probabilities(PL) in the absence of the knowledge of parameter uncertainty.Consistent results obtained from the proposed probabilistic models,compared to the most well-known models,indicate the robustness of the methodology used in this study.The probability models provide a simple,but also efficient decision-making tool in engineering design to quantitatively assess the liquefaction triggering thresholds.展开更多
Recent advances in Global Positioning System （GPS） remote sensing technology allow for a direct estimation of the precipitable water vapor （PWV） from delayed signals transmitted by GPS satellites, which can be ass...Recent advances in Global Positioning System （GPS） remote sensing technology allow for a direct estimation of the precipitable water vapor （PWV） from delayed signals transmitted by GPS satellites, which can be assimilated into numerical models with four-dimensional variational （4DVAR） data assimilation. A mesoscale model and its 4DVAR system are used to access the impacts of assimilating GPS-PWV and hourly rainfall observations on the short-range prediction of a heavy rainfall event on 20 June 2002. The heavy precipitation was induced by a sequence of meso-β-scale convective systems （MCS） along the mei-yu front in China. The experiments with GPS-PWV assimilation cluster and also eliminated the erroneous rainfall successfully simulated the evolution of the observed MCS systems found in the experiment without 4DVAR assimilation. Experiments with hourly rainfall assimilation performed similarly both on the prediction of MCS initiation and the elimination of erroneous systems, however the MCS dissipated much sooner than it did in observations. It is found that the assimilation-induced moisture perturbation and mesoscale low-level jet are helpful for the MCS generation and development. It is also discovered that spurious gravity waves may post serious limitations for the current 4DVAR algorithm, which would degrade the assimilation efficiency, especially for rainfall data. Sensitivity experiments with different observations, assimilation windows and observation weightings suggest that assimilating GPS-PWV can be quite effective, even with the assimilation window as short as 1 h. On the other hand, assimilating rainfall observations requires extreme cautions on the selection of observation weightings and the control of spurious gravity waves.展开更多
A novel method to determine the density and temperature of a system constituted by fermions and/or bosons is proposed based on quantum fluctuations.For fermions system,the results in the limit where the reached temper...A novel method to determine the density and temperature of a system constituted by fermions and/or bosons is proposed based on quantum fluctuations.For fermions system,the results in the limit where the reached temperature T is small and where there is no constraint for the reached temperature T compared to the Fermi energy εf at a given density ρ are given,respectively.Quadrupole and multiplicity fluctuation relations are derived in terms of T/εf.We compared the two set results in the limit when T is much smaller compared to Fermi energy εf and they are consistent,as expected.The classical limit is also obtained for high temperatures and low densities.For bosons system,quadrupole and multiplicity fluctuations using Landau's theory of fluctuations near the critical point for a Bose-Einstein condensate(BEC) at a given density ρ are derived.As an example,we apply our approach to heavy ion collisions using the Constrained Molecular Dynamics model(CoMD) which includes the fermionic statistics.The multiplicity fluctuation quenching for fermions is found in the model and confirmed by experimental data.To reproduce the available experimental data better,we propose a modification of the collision term in the approach to include the possibility of α-α collisions.The relevant Bose-Einstein factor in the collision term is properly taken into account.This approach increases the yields of bosons relative to fermions closer to data.Boson fluctuations become larger than one as expected.展开更多
The paper presents constitutive theories for non-classical thermoviscoelastic fluids with dissipation and memory using a thermodynamic framework based on entirety of velocity gradient tensor. Thus, the conservation an...The paper presents constitutive theories for non-classical thermoviscoelastic fluids with dissipation and memory using a thermodynamic framework based on entirety of velocity gradient tensor. Thus, the conservation and the balance laws used in this work incorporate symmetric as well as antisymmetric part of the velocity gradient tensor. The constitutive theories derived here hold in coand contra-variant bases as well as in Jaumann rates and are derived using convected time derivatives of Green’s and Almansi strain tensors as well as the Cauchy stress tensor and its convected time derivatives in appropriate bases. The constitutive theories are presented in the absence as well as in the presence of the balance of moment of moments as balance law. It is shown that the dissipation mechanism and the fading memory in such fluids are due to stress rates as well as moment rates and their conjugates. The material coefficients are derived for the general forms of the constitutive theories based on integrity. Simplified linear (or quasi-linear) forms of the constitutive theories are also presented. Maxwell, Oldroyd-B and Giesekus constitutive models for non-classical thermoviscoelastic fluids are derived and are compared with those derived based on classical continuum mechanics. Both, compressible and incompressible thermoviscoelastic fluids are considered.展开更多
Ethylene regulates multiple physiological processes in cotton (Gossypium hirsutum L.) ranging from square and boll abscission to senescence. This field study investigated the effect of an ethylene inhibiting compound ...Ethylene regulates multiple physiological processes in cotton (Gossypium hirsutum L.) ranging from square and boll abscission to senescence. This field study investigated the effect of an ethylene inhibiting compound 1-methylcyclopropene (1-MCP) on boll development and the corresponding subtending leaves. The study was conducted in 2011 and 2012 at the Texas A & M Agri-LIFE Research Farm in Burleson County, TX. The study consisted of two rates of 1-MCP (0 and 10 g a.i. ha-1) applied at one and two weeks after first flower. Boll development and subtending leaves were studied on the tagged flowers during the growing season. 1-MCP treatment increased cotton boll weight at 20 days after flowering. This study showed that 1-MCP-treated subtending leaves exhibited decreased membrane damage and lipid peroxidation, and higher chlorophyll content and photosynthetic efficiency at 20 to 30 days after flowering. The healthier state of subtending leaves should have provided more carbohydrates for the fruits which could partially explain the reason for the increased boll weight. However, this beneficial effect of 1-MCP did not last to the end of the growing season and failed to result in a yield increase ultimately. Multiple applications or extending effective duration of 1-MCP is desirable to enhance the activity of 1-MCP to make a significant difference in cotton yield.展开更多
In non-classical thermoelastic solids incorporating internal rotation and conjugate Cauchy moment tensor the mechanical deformation is reversible. This suggests that within the realm of linear mathematical models that...In non-classical thermoelastic solids incorporating internal rotation and conjugate Cauchy moment tensor the mechanical deformation is reversible. This suggests that within the realm of linear mathematical models that only consider small strains and small deformation the mechanical deformation is reversible. Hence, it is possible to recast the conservation and balance laws along with constitutive theories in a form that adjoint A* of the differential operator A in mathematical model is same as the differential operator A. This holds regardless of whether we consider an initial value problem (IVP) (when the integrals over open boundary are neglected) or boundary value problem (BVP). Thus, in such cases Galerkin method with weak form (GM/WF) for BVPs and space-time Galerkin method with weak form (STGM/WF) for IVPs are highly meritorious due to the fact that: 1) the integral form for BVPs is variationally consistent (VC) and 2) the space-time integral forms for IVP are space time variationally consistent (STVC). The consequence of VC and STVC integral forms is that the resulting coefficient matrices are symmetric and positive definite ensuring unconditionally stable computational processes for both BVPs and IVPs. Other benefits of GM/WF and space-time GM/WF are simplicity of specifying boundary conditions and initial conditions, especially traction boundary conditions and initial conditions on curved boundaries due to self-equilibrating nature of the sum of secondary variables that only exist in GM/WF due to concomitant. In fact, zero traction conditions are automatically satisfied in GM/WF, hence need not be specified at all. While VC and STVC feature also exists in least squares process (LSP) and space-time least squares finite element processes (STLSP) for BVPs and IVPs, the ease of specifying traction boundary conditions feature in GM/WF and STGM/WF is highly meritorious compared to LSP and STLSP in which zero traction conditions need to be explicitly specified. A disadvantage of GM/WF and STGM/ WF is that the mathematical models (momentum equations) needed in the desired form contain higher order derivatives of displacements (upto fourth order), hence necessitate use of higher order spaces in their solution. As well known, this problem can be easily overcome in LSP and STLSP by introduction of auxiliary equations and auxiliary variables, thus keeping the highest orders of the derivatives of the dependent variables to one or any other desired order. A serious disadvantage of this approach in LSP is the significant increase in the number of dependent variables, hence poor computational efficiency. In this paper we consider non-classical continuum models for internally polar linear elastic solids in which internal rotations due to displacement gradient tensor (hence internal polar physics) are considered in the conservation and the balance laws and the constitutive theories. For simplicity, we only consider isothermal case;hence energy equation is not part of mathematical model. When using mathematical models derived in displacements in GM/WF and LSP in constructing integral forms, we note that in GM/WF the number of dependent variables is reduced drastically (only three in R3), whereas in case of first order systems used in LSP and STLSP we may have as many as 22 dependent variables for isothermal case. Thus, GM/WF results in dramatic improvement in computational efficiency as well as accuracy when minimally conforming spaces are used for approximations. In this paper we only consider mathematical model in R2 for BVPs (for simplicity). Mathematical models for IVP and BVP in R3 will be considered in subsequent paper. The integral form is derived in R2 using GM/WF. Numerical examples are presented using GM/WF and LSP to demonstrate advantages of finite element process derived using integral form based on GM/WF for non-classical linear theories for solids incorporating internal rotations due to displacement gradient tensor.展开更多
Oil and gas operations depend heavily on water in many different aspects. Water is present wherever there is hydrocarbon production. It is produced along with the hydrocarbons and helps in mobilizing them. It is also ...Oil and gas operations depend heavily on water in many different aspects. Water is present wherever there is hydrocarbon production. It is produced along with the hydrocarbons and helps in mobilizing them. It is also injected into the reservoirs to aid in mobilizing the hydrocarbons, maintain the pressure and increase the recovery of the development project. With water presence, some serious problems occur such as scaling. Scaling is a well-known problematic precipitation caused mainly due to mixing of two incompatible fluids, changes in temperature and pressure conditions and disturbance to thermodynamics and kinetics of reservoir fluids. They can be found at any point of the operations starting down at the formation up to the surface tanks. Scales are directly responsible for compromising the economics and safety of development projects. This review paper is going to include a recap of the importance of water in the oil and gas industry, then review the different types of scales as well as their properties including carbonate and sulfate scales. After that, famous scales from each type is going to be reviewed as well as their properties and precipitation conditions such as Calcium Carbonate CaCO3, Calcium Sulfate CaSO4, Barium Sulfate BaSO4 and Strontium Sulfate SrSO4. Moreover, common practices and precautions steps in the industry are going to be reviewed as well. Finally, the paper presents the common practices used by the operators for scale removal.展开更多
Silencing phytochrome A1 gene (PHYA1) by RNA interference in Upland cotton (Gossypium hirsutum L. cv. Coker 312) had generated PHYA1 RNAi lines with improved fiber quality (longer, stronger and finer fiber). To reveal...Silencing phytochrome A1 gene (PHYA1) by RNA interference in Upland cotton (Gossypium hirsutum L. cv. Coker 312) had generated PHYA1 RNAi lines with improved fiber quality (longer, stronger and finer fiber). To reveal molecular mechanisms that govern fiber development with positive fiber traits, a study of global gene expression profiling of 10-DPA fibers in a PHYA1 RNAi line and its parent Coker 312 was conducted by high-throughput RNA sequencing. A comparative analysis of transcriptomes between the two lines had identified 142 genes that were differentially expressed in the 10-DPA fiber of the RNAi line. Gene Ontology analysis showed that these differentially expressed genes were mainly involved in metabolic pathways, heterocyclic/organic cyclic compound binding and multiple enzyme activities, and cell structures which were reported to play important roles in fiber development. Twenty-eight KEGG pathways were mapped for the 142 genes, and the pathways related to glycolysis/gluconeogenesis and pyruvate metabolism were the most abundant and followed by cytochrome P450-involved pathways, suggesting that fiber improvement could be through the regulation of proteins involved in cytochrome P450 pathways. Genes encoding WRKY transcription factors, sucrose synthase, xyloglucan endotransglucosylase hydrolase, udp-glucuronate: xylan alpha-glucuronosyltransferase, and genes involved in lipid metabolism and ABA/brassinosteroid signal transduction pathways were found differentially expressed in the RNAi line. These genes have direct impacts on cotton fiber quality. The results of this study elucidate molecular signatures and possible mechanisms of fiber improvement in the background of PHYA1 RNAi in cotton and should help for future fine-tuning and programming of cotton fiber development.展开更多
Inferential models are widely used in the chemical industry to infer key process variables, which are challenging or expensive to measure, from other more easily measured variables. The aim of this paper is three-fold...Inferential models are widely used in the chemical industry to infer key process variables, which are challenging or expensive to measure, from other more easily measured variables. The aim of this paper is three-fold: to present a theoretical review of some of the well known linear inferential modeling techniques, to enhance the predictive ability of the regularized canonical correlation analysis (RCCA) method, and finally to compare the performances of these techniques and highlight some of the practical issues that can affect their predictive abilities. The inferential modeling techniques considered in this study include full rank modeling techniques, such as ordinary least square (OLS) regression and ridge regression (RR), and latent variable regression (LVR) techniques, such as principal component regression (PCR), partial least squares (PLS) regression, and regularized canonical correlation analysis (RCCA). The theoretical analysis shows that the loading vectors used in LVR modeling can be computed by solving eigenvalue problems. Also, for the RCCA method, we show that by optimizing the regularization parameter, an improvement in prediction accuracy can be achieved over other modeling techniques. To illustrate the performances of all inferential modeling techniques, a comparative analysis was performed through two simulated examples, one using synthetic data and the other using simulated distillation column data. All techniques are optimized and compared by computing the cross validation mean square error using unseen testing data. The results of this comparative analysis show that scaling the data helps improve the performances of all modeling techniques, and that the LVR techniques outperform the full rank ones. One reason for this advantage is that the LVR techniques improve the conditioning of the model by discarding the latent variables (or principal components) with small eigenvalues, which also reduce the effect of the noise on the model prediction. The results also show that PCR and PLS have comparable performances, and that RCCA can provide an advantage by optimizing its regularization parameter.展开更多
文摘Some bacteria have the ability to co-exist, proliferate and survive in a multicellular community, biofilm. Each participating bacteria can form its colonies and encases itself by a self-produced insoluble extracellular matrix substance (EPS). Microcolonies within biofilm are held together by interactions and bonding of the substances present in the EPS with their separation from the water channels. Similar to insoluble EPS, bacterial microcolonies release soluble exofactors that have direct impacts on the survivability, growth and antibacterial resistivity of other microcolonies made of single- or multi-species bacteria in the same biofilm. How the exofactors of microcolonies of one-type bacteria impact on microcolonies of other-type bacteria is still unclear. We studied about the role of exofactors released from Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa, which are common biofilm-forming pathogenic bacteria. Exofactors facilitate to transform the microenvironment where bacteria can acquire alternative lifestyle with a long survival period and resistivity to certain antimicrobial drugs.
文摘Vine decline disease (VDD) constitutes a menace to melons worldwide. Especially, the one caused by the fungus Monosporascus cannonballus. Thus, resistant plant material must be released to help growers. Hence, our goal was to develop resistant plant material to VDD. More than 600 melon accessions are expected to be tested for disease resistance in M. cannonballus infested soil in Weslaco, Texas, USA, to identify resistance to VDD, and other important traits. So far, at most 7 lines were found to be resistant to VDD and some of them were used to develop elite, muskmelon inbred lines by pedigree breeding following single or double backcrosses. These elite parents were crossed to each other to develop the hybrids M3 and M4. They were also tested in the same infested field in Weslaco. The hybrids were grown using standard commercial practices followed by growers and when their fruits were ready, their roots were sampled as well as scored for disease severity to estimate high and mid-parent heterosis Our results indicate the existence of heterosis regarding resistance to VDD. Thus, resistant plant material can be developed and selection for resistance can be accomplished.
文摘The continued decline in the availability of water from the Ogallala Aquifer in the Texas Panhandle has led to an increased interest in conservation policies designed to extend the life of the aquifer and sustain rural economies. Four counties were chosen for evaluation. This study evaluates the effectiveness of five policies in terms of changes in the saturated thickness, crop mix, water use per acre, and the net present value of farm profits over a 60-year planning horizon. The dynamic optimization models were developed using GAMS for the baseline as well as one for all five of the policy alternatives for each county. Results indicate that the policy scenarios of biotechnology adoption and a water use restriction will conserve the most water among the policies analyzed. In terms of economic returns, the biotechnology adoption policy by far provides the greatest benefit to producers due to yield increases that are estimated with current annual growth rates in new seed varieties. The water use restriction policy, on the other hand, has the lowest net present value of returns, indicating that conservation is accompanied with significant costs to producers. The irrigation adoption technology scenario is the next best policy in terms of net present value of returns (following biotechnology);however, it ranks last in terms of reducing aquifer depletion. It is important to note that while the models do not perfectly predict the factors being evaluated, it is the basis for comparison between the policy scenarios which are important. These comparisons will aid policy makers in determining the most effective strategy to conserve water while simultaneously considering the economic costs to producers. In addition, the results of this study can be applied to other areas facing similar conditions, either currently or in the future, throughout the Texas Panhandle.
文摘Hydrologic and water quality models are often used in assessing the response of environmental processes to human activities and climatic change. However, these models differ in terms of their complexity, requirements, underlying equations, and assumptions, and as such their performance in simulating landscape processes varies. Consequently, a key question that has to be addressed is to select the most suitable model that gives results closest to reality for an intended purpose. In this study, the performance of the basin-wide older version of SWAT is compared with that of the small watershed model APEX to assess the performance of both models at a field scale level. The new restructured version of SWAT (SWAT+) is compared with the older version to determine whether the new changes incorporated in SWAT+ have improved model performance, particularly for small watersheds. The three models were used to simulate the edge of field processes for a 6.6 ha plot located at the USDA-Agricultural Research Station near Riesel, Texas, and to predict water yield, soil, and mineral phosphorous loss from the micro watershed. Results showed that all the uncalibrated models over-predict soil and phosphorous loss in a micro watershed. Uncalibrated SWAT and SWAT+ models simulated water yield satisfactory albeit with low-performance metrics. The calibrated versions simulated water yield with indices close to optimal values. PBIAS as a performance assessment metric was determined to be overly sensitive and prone to numerical errors. SWAT+ will be helpful in the understanding of hydrological and water quality processes at micro watersheds considering that it addresses structural flaws associated with the older version, and the manually calibrated version matches the performance of both APEX and SWAT, despite the latter two undergoing rigorous automatic calibration.
文摘Lectins are carbohydrate-binding proteins with agglutination properties. There is a continuous interest in lectins due to their biological properties that can be exploited for medicinal and therapeutic purposes. The objective of this study was to isolate and characterize lectin activity in Texas Live Oak (Quercus fusiformis). More specifically, the study aimed to determine the lectin’s blood group specificity and pH stability, determine effects of seasonal variation, soil moisture and soil pH on lectin activity. The study also aimed to determine the presence of antifungal activity in Q. fusiformis extracts. Lectin activity was detected and compared via agglutination and protein assays. Protein partial purification was accomplished using diethylaminoethyl ion-exchange chromatography matrix. High Performance Liquid Chromatography (HPLC) was used to assess purity of the lectin. Results showed that Q. fusiformis extracts’ lectin activities are stable at a pH range of 5.2 - 9.2 but with a significant decrease in activity above pH 9.2. The lectin activity was significantly higher when assayed against sheep red blood cells as compared to other blood groups tested. Quercus fusiformis extract is devoid of antifungal activity against Aspergillus niger and Rhizopus stolonifer. The effects of seasonal variation, soil moisture and soil pH do not significantly correlate with lectin activity. Results from HPLC showed presence of three peaks indicating a partial purification of the Q. fusiformis lectin.
文摘We analyzed two types of crude oil samples: Middle Eastern crude oil and Texas crude oil by using a residual gas analyzer (RGA) based on the linear quadrupole principle. This portable mass analyzer is capable of measuring hydrocarbons with masses of up to 300 atomic mass units (amu) as well as low mass targets, such as methane and carbon dioxide at ppm level concentrations. The generated mass spectra revealed differences in the composition and signal intensity of hydrocarbons of Middle Eastern and Texas crude oil samples. Even if RGA 300 is manufactured to be served as a detailed gas analysis of vacuum systems, we have shown that it is sensitively capable of detection of hydrocarbons and it enables one to qualitative and quantitative analysis of the composition of the crude oils.
基金supported by the National Natural Science Foundation of China (Grant Nos. 51279116)the New Teacher Fund of Ministry of Education of China (Grant No. 20120181120124)+1 种基金the Excellent Scholar Fund of Sichuan UniversityOpen Fund Program of State key Laboratory of Hydraulics and River Engineering, Sichuan University, China (Grant No. 0901)
文摘Assessment of debris flow hazards is important for developing measures to mitigate the loss of life and property and to minimize environmental damage. Two modified uncertainty models, Set Pair Analysis （SPA） and modified Set Pair Analysis （mSPA）, were suggested to assess the regional debris flow hazard. A ease study was conducted in seven towns of the Beichuan county, Sichuan Province, China, to test and compare the application of these two models in debris flow hazard assessment. The results showed that mSPA only can fit for value-variables, but not for non value-variable assessment indexes, Furthermore, as for a given assessment index xi, mSPA only considers two cases, namely, when grade value increases with xi and when grade value decreases with xi. Thus, mSPA can not be used for debris flow hazard assessment but SPA is credible for the assessment because there are no limitations when using SPA model to assess the debris flow hazard. Therefore, in this study SPA is proposed for assessing debris flow hazard.
文摘The intestinal microbiota is the collection of the living microorganisms(bacteria, fungi, protozoa, and viruses) inhabiting the gastrointestinal tract. Novel bacterial identification approaches have revealed that the gastrointestinal microbiota of dogs and cats is, similarly to humans, a highly complex ecosystem. Studies in dogs and cats have demonstrated that acute and chronic gastrointestinal diseases, including inflammatory bowel disease(IBD), are associated with alterations in the small intestinal and fecal microbial communities. Of interest is that these alterations are generally similar to the dysbiosis observed in humans with IBD or animal models of intestinal inflammation, suggesting that microbial responses to inflammatory conditions of the gut are conserved across mammalian host types. Studies have also revealed possible underlying susceptibilities in the innate immune system of dogs and cats with IBD, which further demonstrate the intricate relationship between gut microbiota and host health. Commonly identified microbiome changes in IBD are decreases in bacterial groups within the phyla Firmicutes and Bacteroidetes, and increases within Proteobacteia. Furthermore, a reduction in the diversity of Clostridium clusters XIVa and IV(i.e., Lachnospiraceae and Clostridium coccoides subgroups) are associated with IBD, suggesting that these bacterial groups may play an important role in maintenance of gastrointestinal health. Future studies are warranted to evaluate the functional changes associated with intestinal dysbiosis in dogs and cats.
基金Supported by the Overseas Scholars of Heilongjiang Province of China (1151hq006)
文摘A support(denoted AM) was prepared using pseudo-boehmite and mordenite.Ni-B and NiPtB amorphous catalysts were prepared on the support by the impregnation method followed by chemical reduction with a KBH4 solution.And the catalysts were characterized by X-ray diffraction(XRD),environment scanning electron microscope(ESEM),inductively coupled plasma(ICP),H2-temperature programmed reduction(H2-TPR),differential thermal analysis(DTA),and BET.Benzene hydrogenation was used as a probe reaction to evaluate the effect of addition of small quantities of Pt on the NiB/AM catalyst.The results show that Pt can promote the reduction of NiO and the formation of active sites,leading to smaller catalyst particles and better dispersion of active metal particles on the support.The catalytic activity,sulfur resistance and thermal stability were remarkably improved by Pt doping of the NiB/AM catalyst.
基金supported by ENRESA and the European Commissionsupport given by CNPq(Conselho Nacional de Desenvolvimento Cientíco e Tecnológico)and the assistance of the Ministerio de Ciencia y Tecnología of Spain through research grant(BIA2008-06537)
文摘A fully coupled thermo-hydro-mechano-chemical（THMC） formulation is described in this paper.Special attention is paid to phenomena likely to be encountered in clay barriers used as engineered barriers in the disposal of nuclear radioactive waste.The types of processes considered in the chemical formulation include hydrolysis,complex formation,oxidation/reduction reactions,acid/base reactions,precipitation/dissolution of minerals and cation exchange.Both kinetics-and equilibrium-controlled reactions are incorporated.The formulation is implemented in a numerical code.An application is presented concerning the performance of a large-scale in-situ heating test simulating high-level radioactive waste repository conditions.
文摘In this context,two different approaches of soil liquefaction evaluation using a soft computing technique based on the worldwide standard penetration test(SPT) databases have been studied.Gene expression programming(GEP) as a gray-box modeling approach is used to develop different deterministic models in order to evaluate the occurrence of soil liquefaction in terms of liquefaction field performance indicator(LI) and factor of safety(FS) in logistic regression and classification concepts.The comparative plots illustrate that the classification concept-based models show a better performance than those based on logistic regression.In the probabilistic approach,a calibrated mapping function is developed in the context of Bayes’ theorem in order to capture the failure probabilities(PL) in the absence of the knowledge of parameter uncertainty.Consistent results obtained from the proposed probabilistic models,compared to the most well-known models,indicate the robustness of the methodology used in this study.The probability models provide a simple,but also efficient decision-making tool in engineering design to quantitatively assess the liquefaction triggering thresholds.
文摘Recent advances in Global Positioning System （GPS） remote sensing technology allow for a direct estimation of the precipitable water vapor （PWV） from delayed signals transmitted by GPS satellites, which can be assimilated into numerical models with four-dimensional variational （4DVAR） data assimilation. A mesoscale model and its 4DVAR system are used to access the impacts of assimilating GPS-PWV and hourly rainfall observations on the short-range prediction of a heavy rainfall event on 20 June 2002. The heavy precipitation was induced by a sequence of meso-β-scale convective systems （MCS） along the mei-yu front in China. The experiments with GPS-PWV assimilation cluster and also eliminated the erroneous rainfall successfully simulated the evolution of the observed MCS systems found in the experiment without 4DVAR assimilation. Experiments with hourly rainfall assimilation performed similarly both on the prediction of MCS initiation and the elimination of erroneous systems, however the MCS dissipated much sooner than it did in observations. It is found that the assimilation-induced moisture perturbation and mesoscale low-level jet are helpful for the MCS generation and development. It is also discovered that spurious gravity waves may post serious limitations for the current 4DVAR algorithm, which would degrade the assimilation efficiency, especially for rainfall data. Sensitivity experiments with different observations, assimilation windows and observation weightings suggest that assimilating GPS-PWV can be quite effective, even with the assimilation window as short as 1 h. On the other hand, assimilating rainfall observations requires extreme cautions on the selection of observation weightings and the control of spurious gravity waves.
文摘A novel method to determine the density and temperature of a system constituted by fermions and/or bosons is proposed based on quantum fluctuations.For fermions system,the results in the limit where the reached temperature T is small and where there is no constraint for the reached temperature T compared to the Fermi energy εf at a given density ρ are given,respectively.Quadrupole and multiplicity fluctuation relations are derived in terms of T/εf.We compared the two set results in the limit when T is much smaller compared to Fermi energy εf and they are consistent,as expected.The classical limit is also obtained for high temperatures and low densities.For bosons system,quadrupole and multiplicity fluctuations using Landau's theory of fluctuations near the critical point for a Bose-Einstein condensate(BEC) at a given density ρ are derived.As an example,we apply our approach to heavy ion collisions using the Constrained Molecular Dynamics model(CoMD) which includes the fermionic statistics.The multiplicity fluctuation quenching for fermions is found in the model and confirmed by experimental data.To reproduce the available experimental data better,we propose a modification of the collision term in the approach to include the possibility of α-α collisions.The relevant Bose-Einstein factor in the collision term is properly taken into account.This approach increases the yields of bosons relative to fermions closer to data.Boson fluctuations become larger than one as expected.
文摘The paper presents constitutive theories for non-classical thermoviscoelastic fluids with dissipation and memory using a thermodynamic framework based on entirety of velocity gradient tensor. Thus, the conservation and the balance laws used in this work incorporate symmetric as well as antisymmetric part of the velocity gradient tensor. The constitutive theories derived here hold in coand contra-variant bases as well as in Jaumann rates and are derived using convected time derivatives of Green’s and Almansi strain tensors as well as the Cauchy stress tensor and its convected time derivatives in appropriate bases. The constitutive theories are presented in the absence as well as in the presence of the balance of moment of moments as balance law. It is shown that the dissipation mechanism and the fading memory in such fluids are due to stress rates as well as moment rates and their conjugates. The material coefficients are derived for the general forms of the constitutive theories based on integrity. Simplified linear (or quasi-linear) forms of the constitutive theories are also presented. Maxwell, Oldroyd-B and Giesekus constitutive models for non-classical thermoviscoelastic fluids are derived and are compared with those derived based on classical continuum mechanics. Both, compressible and incompressible thermoviscoelastic fluids are considered.
文摘Ethylene regulates multiple physiological processes in cotton (Gossypium hirsutum L.) ranging from square and boll abscission to senescence. This field study investigated the effect of an ethylene inhibiting compound 1-methylcyclopropene (1-MCP) on boll development and the corresponding subtending leaves. The study was conducted in 2011 and 2012 at the Texas A & M Agri-LIFE Research Farm in Burleson County, TX. The study consisted of two rates of 1-MCP (0 and 10 g a.i. ha-1) applied at one and two weeks after first flower. Boll development and subtending leaves were studied on the tagged flowers during the growing season. 1-MCP treatment increased cotton boll weight at 20 days after flowering. This study showed that 1-MCP-treated subtending leaves exhibited decreased membrane damage and lipid peroxidation, and higher chlorophyll content and photosynthetic efficiency at 20 to 30 days after flowering. The healthier state of subtending leaves should have provided more carbohydrates for the fruits which could partially explain the reason for the increased boll weight. However, this beneficial effect of 1-MCP did not last to the end of the growing season and failed to result in a yield increase ultimately. Multiple applications or extending effective duration of 1-MCP is desirable to enhance the activity of 1-MCP to make a significant difference in cotton yield.
文摘In non-classical thermoelastic solids incorporating internal rotation and conjugate Cauchy moment tensor the mechanical deformation is reversible. This suggests that within the realm of linear mathematical models that only consider small strains and small deformation the mechanical deformation is reversible. Hence, it is possible to recast the conservation and balance laws along with constitutive theories in a form that adjoint A* of the differential operator A in mathematical model is same as the differential operator A. This holds regardless of whether we consider an initial value problem (IVP) (when the integrals over open boundary are neglected) or boundary value problem (BVP). Thus, in such cases Galerkin method with weak form (GM/WF) for BVPs and space-time Galerkin method with weak form (STGM/WF) for IVPs are highly meritorious due to the fact that: 1) the integral form for BVPs is variationally consistent (VC) and 2) the space-time integral forms for IVP are space time variationally consistent (STVC). The consequence of VC and STVC integral forms is that the resulting coefficient matrices are symmetric and positive definite ensuring unconditionally stable computational processes for both BVPs and IVPs. Other benefits of GM/WF and space-time GM/WF are simplicity of specifying boundary conditions and initial conditions, especially traction boundary conditions and initial conditions on curved boundaries due to self-equilibrating nature of the sum of secondary variables that only exist in GM/WF due to concomitant. In fact, zero traction conditions are automatically satisfied in GM/WF, hence need not be specified at all. While VC and STVC feature also exists in least squares process (LSP) and space-time least squares finite element processes (STLSP) for BVPs and IVPs, the ease of specifying traction boundary conditions feature in GM/WF and STGM/WF is highly meritorious compared to LSP and STLSP in which zero traction conditions need to be explicitly specified. A disadvantage of GM/WF and STGM/ WF is that the mathematical models (momentum equations) needed in the desired form contain higher order derivatives of displacements (upto fourth order), hence necessitate use of higher order spaces in their solution. As well known, this problem can be easily overcome in LSP and STLSP by introduction of auxiliary equations and auxiliary variables, thus keeping the highest orders of the derivatives of the dependent variables to one or any other desired order. A serious disadvantage of this approach in LSP is the significant increase in the number of dependent variables, hence poor computational efficiency. In this paper we consider non-classical continuum models for internally polar linear elastic solids in which internal rotations due to displacement gradient tensor (hence internal polar physics) are considered in the conservation and the balance laws and the constitutive theories. For simplicity, we only consider isothermal case;hence energy equation is not part of mathematical model. When using mathematical models derived in displacements in GM/WF and LSP in constructing integral forms, we note that in GM/WF the number of dependent variables is reduced drastically (only three in R3), whereas in case of first order systems used in LSP and STLSP we may have as many as 22 dependent variables for isothermal case. Thus, GM/WF results in dramatic improvement in computational efficiency as well as accuracy when minimally conforming spaces are used for approximations. In this paper we only consider mathematical model in R2 for BVPs (for simplicity). Mathematical models for IVP and BVP in R3 will be considered in subsequent paper. The integral form is derived in R2 using GM/WF. Numerical examples are presented using GM/WF and LSP to demonstrate advantages of finite element process derived using integral form based on GM/WF for non-classical linear theories for solids incorporating internal rotations due to displacement gradient tensor.
文摘Oil and gas operations depend heavily on water in many different aspects. Water is present wherever there is hydrocarbon production. It is produced along with the hydrocarbons and helps in mobilizing them. It is also injected into the reservoirs to aid in mobilizing the hydrocarbons, maintain the pressure and increase the recovery of the development project. With water presence, some serious problems occur such as scaling. Scaling is a well-known problematic precipitation caused mainly due to mixing of two incompatible fluids, changes in temperature and pressure conditions and disturbance to thermodynamics and kinetics of reservoir fluids. They can be found at any point of the operations starting down at the formation up to the surface tanks. Scales are directly responsible for compromising the economics and safety of development projects. This review paper is going to include a recap of the importance of water in the oil and gas industry, then review the different types of scales as well as their properties including carbonate and sulfate scales. After that, famous scales from each type is going to be reviewed as well as their properties and precipitation conditions such as Calcium Carbonate CaCO3, Calcium Sulfate CaSO4, Barium Sulfate BaSO4 and Strontium Sulfate SrSO4. Moreover, common practices and precautions steps in the industry are going to be reviewed as well. Finally, the paper presents the common practices used by the operators for scale removal.
文摘Silencing phytochrome A1 gene (PHYA1) by RNA interference in Upland cotton (Gossypium hirsutum L. cv. Coker 312) had generated PHYA1 RNAi lines with improved fiber quality (longer, stronger and finer fiber). To reveal molecular mechanisms that govern fiber development with positive fiber traits, a study of global gene expression profiling of 10-DPA fibers in a PHYA1 RNAi line and its parent Coker 312 was conducted by high-throughput RNA sequencing. A comparative analysis of transcriptomes between the two lines had identified 142 genes that were differentially expressed in the 10-DPA fiber of the RNAi line. Gene Ontology analysis showed that these differentially expressed genes were mainly involved in metabolic pathways, heterocyclic/organic cyclic compound binding and multiple enzyme activities, and cell structures which were reported to play important roles in fiber development. Twenty-eight KEGG pathways were mapped for the 142 genes, and the pathways related to glycolysis/gluconeogenesis and pyruvate metabolism were the most abundant and followed by cytochrome P450-involved pathways, suggesting that fiber improvement could be through the regulation of proteins involved in cytochrome P450 pathways. Genes encoding WRKY transcription factors, sucrose synthase, xyloglucan endotransglucosylase hydrolase, udp-glucuronate: xylan alpha-glucuronosyltransferase, and genes involved in lipid metabolism and ABA/brassinosteroid signal transduction pathways were found differentially expressed in the RNAi line. These genes have direct impacts on cotton fiber quality. The results of this study elucidate molecular signatures and possible mechanisms of fiber improvement in the background of PHYA1 RNAi in cotton and should help for future fine-tuning and programming of cotton fiber development.
文摘Inferential models are widely used in the chemical industry to infer key process variables, which are challenging or expensive to measure, from other more easily measured variables. The aim of this paper is three-fold: to present a theoretical review of some of the well known linear inferential modeling techniques, to enhance the predictive ability of the regularized canonical correlation analysis (RCCA) method, and finally to compare the performances of these techniques and highlight some of the practical issues that can affect their predictive abilities. The inferential modeling techniques considered in this study include full rank modeling techniques, such as ordinary least square (OLS) regression and ridge regression (RR), and latent variable regression (LVR) techniques, such as principal component regression (PCR), partial least squares (PLS) regression, and regularized canonical correlation analysis (RCCA). The theoretical analysis shows that the loading vectors used in LVR modeling can be computed by solving eigenvalue problems. Also, for the RCCA method, we show that by optimizing the regularization parameter, an improvement in prediction accuracy can be achieved over other modeling techniques. To illustrate the performances of all inferential modeling techniques, a comparative analysis was performed through two simulated examples, one using synthetic data and the other using simulated distillation column data. All techniques are optimized and compared by computing the cross validation mean square error using unseen testing data. The results of this comparative analysis show that scaling the data helps improve the performances of all modeling techniques, and that the LVR techniques outperform the full rank ones. One reason for this advantage is that the LVR techniques improve the conditioning of the model by discarding the latent variables (or principal components) with small eigenvalues, which also reduce the effect of the noise on the model prediction. The results also show that PCR and PLS have comparable performances, and that RCCA can provide an advantage by optimizing its regularization parameter.
