The urgent need to expand the donor pool in order to attend to the growing demand for liver transplantation has obliged physicians to consider the use of suboptimal liver grafts and also to redefine the preservation s...The urgent need to expand the donor pool in order to attend to the growing demand for liver transplantation has obliged physicians to consider the use of suboptimal liver grafts and also to redefine the preservation strategies. This review examines the different methods of liver graft preservation, focusing on the latest advances in both static cold storage and machine perfusion(MP). The new strategies for static cold storage are mainly designed to increase the fatty liver graft preservation via the supplementation of commercial organ preservation solutions with additives. In this paper we stress the importance of carrying out effective graft washout after static cold preservation, and present a detailed discussion of the future perspectives for dynamic graft preservation using MP at different temperatures(hypothermia at 4 ℃, normothermia a t 3 7 ℃ and subnormothermia at 20 ℃- 2 5 ℃). Finally, we highlight some emerging applications of regenerative medicine in liver graft preservation. In conclusion, this review discusses the "state of the art" and future perspectives in static and dynamic liver graft preservation in order to improve graft viability.展开更多
Several previous studies have indicated that nest sanitation behavior is a general adaptation in altricial birds,with egg recog nition capacity evolvi ng as a specific response to in terspecific brood parasitism(IBP)....Several previous studies have indicated that nest sanitation behavior is a general adaptation in altricial birds,with egg recog nition capacity evolvi ng as a specific response to in terspecific brood parasitism(IBP).However,a rece nt study suggested an alternative hypothesis,con cludi ng that con specific brood parasitism(CBP)selects for egg rejection in thrushes,with IBP as a by-product.In the present study,we used a spectrophotometer to quantify egg coloration and egg mimicry and performed artificial parasitism experiments in the grey?backed thrush(Turdus hortulorum).We showed that individuals of this species rejected 100%of 12 foreign eggs,without IBP or CBP detected.In a review of previous studies,we also discuss possible explanations for the high egg rejection rate in the grey-backed thrush and suggest areas for future study.Altricial birds have evolved advaneed reproductive behavior to in crease the fitn ess of their offspring by buildi ng elaborate structures(i.e.,nests),in which they lay eggs and rear their nestlings(Hansell,2000).Bird nests not only provide a suitable place for nestling development,but also act as a concealed location for safety from predators.Furthermore,bird parents have evolved nest sanitation behavior to clean foreig n objects from their n ests,in eluding feces,eggshells,branches,and leaves,because they induce predation,facilitate microorganism growth,damage eggs,or hurt nestlings during brooding(Guigueno&Sealy,2012).Therefore,nest sanitation has evolved as a general behavior in altricial birds for distinguishing between egg-shaped and non-egg-shaped objects.展开更多
Background:Floods and other extreme events have disastrous effects on wetland breeding birds.However,such events and their consequences are difficult to study due to their rarity and unpredictable occurrence.Methods:H...Background:Floods and other extreme events have disastrous effects on wetland breeding birds.However,such events and their consequences are difficult to study due to their rarity and unpredictable occurrence.Methods:Here we compared nest-sites chosen by Reed Parrotbills(Paradoxornis heudei) during June-August 2016 in Yongnianwa Wetlands,Hebei Province,China,before and after an extreme flooding event.Results:Twenty-three nests were identified before and 13 new nests after the flood.There was no significant difference in most nest-site characteristics,such as distance from the road,height of the reeds in which nests were built,or nest volume before or after the flood.However,nests after the flood were located significantly higher in the vegetation compared to before the flood(mean ± SE:1.17 ± 0.13 m vs.0.75 ± 0.26 m,p < 0.01).However,predation rate also increased significantly after the flood(67% vs.25%,p = 0.030).Conclusions:Our results suggested that Reed Parrotbills demonstrated behavioral plasticity in their nest-site selection.Thus,they appeared to increase the height of their nests in response to the drastically changing water levels in reed wetlands,to reduce the likelihood that their nests would be submerged again by flooding.However,predation rate also increased significantly after the flood,suggesting that the change in nest height to combat the threat of flooding made the nests more susceptible to other threats,such as predation.Animals' response to rare climatic events,such as flooding,may produce ecological traps if they make the animals more susceptible to other kinds of threats they are more likely to continue to encounter.展开更多
It is well known that balance control is affected by aging, neurological and orthopedic conditions. Poor balance control during gait and postural maintenance are associated with disability, falls and increased mortali...It is well known that balance control is affected by aging, neurological and orthopedic conditions. Poor balance control during gait and postural maintenance are associated with disability, falls and increased mortality. Gait initiation-the transient period between the quiet standing posture and steady state walking-is a functional task that is classically used in the literature to investigate how the central nervous system(CNS) controls balance during a whole-body movement involving change in the base of support dimensions and center of mass progression. Understanding how the CNS in able-bodied subjects exerts this control during such a challenging task is a prerequisite to identifying motor disorders in populations with specific impairments of the postural system. It may also provide clinicians with objective measures to assess the efficiency of rehabilitation programs and better target interventions according to individual impairments. The present review thus proposes a state-of-the-art analysis on:(1) the balance control mechanisms in play during gait initiation in able bodied subjects and in the case of some frail populations; and(2) the biomechanical parameters used in the literature to quantify dynamic stability during gait initiation. Balance control mechanisms reviewed in this article included anticipatory postural adjustments, stance leg stiffness, foot placement, lateral ankle strategy, swing foot strike pattern and vertical center of mass braking. Based on this review, the following viewpoints were put forward:(1) dynamic stability during gait initiation may share a principle of homeostatic regulation similar to most physiological variables, where separate mechanisms need to be coordinated to ensure stabilization of vital variables, and consequently; and(2) rehabilitation interventions which focus on separate or isolated components of posture, balance, or gait may limit the effectiveness of current clinical practices.展开更多
Molecular frame photoemission is a very sensitive probe of the photoionization （PI） dynamics of molecules. This paper reports a comparative study of non-resonant and resonant photoionization of D2 induced by VUV cir...Molecular frame photoemission is a very sensitive probe of the photoionization （PI） dynamics of molecules. This paper reports a comparative study of non-resonant and resonant photoionization of D2 induced by VUV circularly polarized synchrotron radiation at SOLEIL at the level of the molecular frame photoelectron angular distributions （MFPADs）. We use the vector correlation method which combines imaging and time-of-flight resolved electron-ion coincidence techniques, and a generalized formalism for the expression of the Ⅰ（χ, θe, Фe） MFPADs, where χ is the orientation of the molecular axis with respect to the light quantization axis and （θe, Фe） the electron emission direction in the molecular frame. Selected MFPADs for a molecule aligned parallel or perpendicular to linearly polarized light, or perpendicular to the propagation axis of circularly polarized light, are presented for dissociative photoionization （DPI） of D2 at two photon excitation energies, hv=19 eV, where direct PI is the only channel opened, and hv=32.5 eV, i.e. in the region involving resonant excitation of Q1 and Q2 doubly excited state series. We discuss in particular the properties of the circular dichroism characterizing photoemission in the molecular frame for direct and resonant PI. In the latter case, a remarkable behavior is observed which may be attributed to the interference occurring between undistinguishable autoionization decay channels.展开更多
Climate change has advanced the phenology of many organisms. Migratory animals face particular problems because climate change in the breeding and the wintering range may be asynchronous, preventing rapid response to ...Climate change has advanced the phenology of many organisms. Migratory animals face particular problems because climate change in the breeding and the wintering range may be asynchronous, preventing rapid response to changing conditions. Advancement in timing of spring migration may have carry-over effects to other parts of the annual cycle, simply because advancement of one event in the annual cycle also advances subsequent events, gradually causing a general shift in the timing of the entire annual cycle. Such a phenotypic shift could generate accumulating effects over the years for individuals, but also across generations. Here we test this novel hypothesis of phenotypic response to climate change by using long-term data on the Arctic tern Sterna paradisaea. Mean breeding date advanced by almost three weeks during the last 70 years. Annual arrival date at the breeding grounds during a period of 47 years was predicted by environmental conditions in the winter quarters in the Southern Ocean near the Antarctic and by mean breeding date the previous year. Annual mean breeding date was only marginally determined by timing of arrival the current year, but to a larger extent by arrival date and breeding date the previous year. Learning affected arrival date as shown by a positive correlation between arrival date in year （i ＋ 1） relative to breeding date in year （i） and the selective advantage of early breeding in year （i）. This provides a mechanism for changes in arrival date being adjusted to changing environmental conditions. This study suggests that adaptation to changing climatic conditions can be achieved through learning from year to year展开更多
The use of a broadband, frequency shaped femtosecond laser on translationally cold cesium molecules has recently demonstrated to be a very efficient method of cooling also the vibrational degree of freedom. A sample o...The use of a broadband, frequency shaped femtosecond laser on translationally cold cesium molecules has recently demonstrated to be a very efficient method of cooling also the vibrational degree of freedom. A sample of cold molecules, initially distributed over several vibrational levels, has thus been transfered into a single selected vibrational level of the singlet X^1∑g ground electronic state. Our method is based on repeated optical pumping by laser light with a spectrum broad enough to excite all populated vibrational levels but limited in its frequency bandwidth with a spatial light modulator. In such a way we are able to eliminate transitions from the selected level, in which molecules accumulate. In this paper we briefly report the main experimental results and then address, in a detailed way by computer simulations, the perspectives for a ＂complete＂ cooling of the molecules, including also the rotational degree of freedom. Since the pumping process strongly depends on the relative shape of the ground and excited potential curves, ro-vibrational cooling through different excited states is theoretically compared.展开更多
Absorption spectra of the mixed chain nickelates （（NdxY1-x）2BaNiO5 were measured for different x. Experimentally two evidences for the presence of non-equivalent rare-earth centers （NEREC） were found. First, the ...Absorption spectra of the mixed chain nickelates （（NdxY1-x）2BaNiO5 were measured for different x. Experimentally two evidences for the presence of non-equivalent rare-earth centers （NEREC） were found. First, the linewidths show a very strong broadening for x when the calculated distribution over NEREC is wide. Second, a compficated lineshape of the lowest-frequency line in the region of the 4I9/2→4I1/2 electronic lransition is in good agreement with statistics of NEREC. A simple modeling for the line broadening due to NEREC is suggested.展开更多
Background:The uropygial gland is an exocrine gland located above the tail of birds that produces a diverse range of biochemicals.It has been hypothesized to be involved in chemical protection,water-proofing and maint...Background:The uropygial gland is an exocrine gland located above the tail of birds that produces a diverse range of biochemicals.It has been hypothesized to be involved in chemical protection,water-proofing and maintenance of plumage brightness.Although these not necessarily mutually exclusive functions have received some empirical support,there has been little empirical research on the function of water-proofing.Methods:Here we analyzed data for 229 individual eiders(Somateria mollissima)collected by Danish hunters during 2016-2018.Results:The Eider is a sea-duck that spends almost its entire life in sea water emphasizing water-proofing of the plumage.The size of the uropygial gland increased with body mass in males,but not in females,and it increased with age.The size of the uropygial gland decreased during winter. Eiders with small uropygial glands grew their feathers at a fast rate.Eiders with large wing areas had large uropygial glands. Conclusions:These findings are consistent with large uropygial glands playing a role in water-proofing during molt and foraging, but also that uropygial glands may play a role in chemical defense.展开更多
Inflammatory bowel disease (IBD) is profoundly associated with extraintestinal manifestations (EIM) that can involve almost every organ in our body. Although the exact etiology of IBD is still poorly understood, it is...Inflammatory bowel disease (IBD) is profoundly associated with extraintestinal manifestations (EIM) that can involve almost every organ in our body. Although the exact etiology of IBD is still poorly understood, it is generally characterized by an overly aggressive inflammatory response in the intestinal mucosa. Renal damage is one of the manifestations encountered in Crohn’s disease (CD) and ulcerative colitis (UC) and it accounts for 4% - 23% of IBD patients. The common renal complications of IBD include: glomerulonephritis, tubulointerstitial nephritis, nephrolithiasis, amyloidosis and iatrogenic complications of IBD treatment. Several hypotheses have emerged to explain the pathogenic mechanisms underlying the prevalence of IBD-induced kidney injuries. The present work aims to elucidate the pathological principles that drive secondary renal injury in individuals with IBD and highlight the currently used therapeutic strategies for evaluating, monitoring and treating kidney complications-related IBD.展开更多
AIM To evaluate the relationship between the state of transplanted liver graft and the recipient quality of life(QOL) of histologically proven lesions in a 10-year post liver transplantation(LT) cohort of patients. ME...AIM To evaluate the relationship between the state of transplanted liver graft and the recipient quality of life(QOL) of histologically proven lesions in a 10-year post liver transplantation(LT) cohort of patients. METHODS Seventy-two recipients with a functional first graft at 10 years post-LT underwent liver biopsy and completed a QOL questionnaire. Logistic regression analysis was used to explore associations between histological, clinical andQOL criteria. RESULTS Ten years after LT, fibrosis was detected in 53% of patients, and affected the general health perception, while ductopenia, present in 36%, affected the well-being(P = 0.05). Hepatic steatosis(HS) was present in 33% of patients and was associated with the worst QOL score on multiple domains. When compared to patients without HS, patients with HS had significantly higher incidence of fibrosis(P = 0.03), hepatitis C virus(HCV) infection(P = 0.007), and more patients had retired from their job(P = 0.03). Recurrent or de novo HCV-associated fibrosis and patient retirement as objective variables, and abdominal pain or discomfort and joint aches or pains as subjective variables, emerged as independent determinants of HS. CONCLUSION Long-term liver graft lesions, mainly HS presumably as a surrogate marker of HCV infection, may have a substantial impact on QOL 10 years after LT.展开更多
Picosecond pulse radiolysis of neat tetrahydrofuran (THF) shows a fast decay of the solvated electron within 2.5ns.The decay of the solvated electron observed at 790nm is because of spur reaction.A numerical simulatio...Picosecond pulse radiolysis of neat tetrahydrofuran (THF) shows a fast decay of the solvated electron within 2.5ns.The decay of the solvated electron observed at 790nm is because of spur reaction.A numerical simulation using time dependent Smoluchowski equation containing a sink term with a distance dependent reaction rate is used to fit the pulse-probe data and shows that the geminate reaction can proceed at long distance in this low polar solvent.展开更多
There are mainly two approaches to the multifractal analysis of measures. The first one,which is used in applications and in studying problems arising from dynamical systems,uses a hierarchy of boxes. The second one,w...There are mainly two approaches to the multifractal analysis of measures. The first one,which is used in applications and in studying problems arising from dynamical systems,uses a hierarchy of boxes. The second one,which is more satisfactory from the viewpoint of geometric measure theory,uses more intrinsic concepts. This article is an account of a work by J.Barral,F.Ben Nasr,and J.Peyriére [3] which provides a bridge between these two theories.展开更多
The single-particle spectrum obtained from the relativistic mean field （RMF） theory is used to extract the shell correction energy with the Strutinsky method. Considering the delicate balance between the plateau con...The single-particle spectrum obtained from the relativistic mean field （RMF） theory is used to extract the shell correction energy with the Strutinsky method. Considering the delicate balance between the plateau condition in the Strutinsky smoothing procedure and the convergence for the total binding energy, the proper space sizes used in solving the RMF equations are investigated in detail by taking ^208 Pb as an example. With the proper space sizes, almost the same shell correction energies are obtained by solving the RMF equations either on basis space or in coordinate space.展开更多
Background: Feathers are a defining feature of birds with multiple functions such as flight, insulation, protection against predation and signaling. Feathers are lost during the annual molt while the rate of such loss...Background: Feathers are a defining feature of birds with multiple functions such as flight, insulation, protection against predation and signaling. Feathers are lost during the annual molt while the rate of such loss at other times of the year and its fitness consequences remain poorly known.Methods: I used information on the number and the mass of feathers for 160 individuals belonging to 85 species of birds in general linear mixed models to analyze allometry of feathers and to investigate possible factors explaining variation in the number of feathers. A phylogenetic effect was assessed by quantifying the random effect of genus.Results: The total mass of feathers increased isometrically with body mass, while the total number of feathers and the mean mass of feathers showed negative allometry. Negative allometry implied that small-sized species had relatively many small feathers. There was a negative association between the number of feathers and migration distance. The total number of feathers initially increased during fall and winter, consistent with individuals growing more feathers later during the year or with individuals with fewer feathers selectively disappearing from the population. In contrast, the number of feathers decreased from winter through spring and summer.Conclusions: These findings suggest that thermoregulation has affected the evolution of the number and the size of feathers, there is selection against feather loss, and that the number of feathers varies across seasons.展开更多
The molar extinction coefficients at the absorption maximum of the solvated electron spectrum have been evaluated to be 900,970,and 1000 mol^(-1).m^2 for 1,2-ethanediol (12ED),1,2-propanediol (12PD),and 1,3-propanedio...The molar extinction coefficients at the absorption maximum of the solvated electron spectrum have been evaluated to be 900,970,and 1000 mol^(-1).m^2 for 1,2-ethanediol (12ED),1,2-propanediol (12PD),and 1,3-propanediol (13PD),respectively.These values are two-third or three-fourth of the value usually reported in the published report. Picosecond pulse radiolysis studies have aided in depicting the radiolytic yield of the solvated electron in these sol- vents as a function of time from picosecond to microsecond.The radiolytic yield in these viscous solvents is found to be strongly different from that of the water solution.The temperature dependent absorption spectra of the solvated electron in 12ED,12PD,and 13PD have been also investigated.In all the three solvents,the optical spectra shift to the red with increasing temperature.While the shape of the spectra does not change in 13PD,a widening on the blue side of the absorption band is observed in 12ED and 12PD at elevated temperatures.展开更多
基金Supported by Grant from Fondo de Investigaciones Sanitarias,No.FIS PI12/00519Eirini Pantazi is the recipient of a fellowship from Agència de Gestiód’Ajuts Universitaris i de Recerca,No.2012FI_B00382,Generalitat de Catalunya,Barcelona,Spain
文摘The urgent need to expand the donor pool in order to attend to the growing demand for liver transplantation has obliged physicians to consider the use of suboptimal liver grafts and also to redefine the preservation strategies. This review examines the different methods of liver graft preservation, focusing on the latest advances in both static cold storage and machine perfusion(MP). The new strategies for static cold storage are mainly designed to increase the fatty liver graft preservation via the supplementation of commercial organ preservation solutions with additives. In this paper we stress the importance of carrying out effective graft washout after static cold preservation, and present a detailed discussion of the future perspectives for dynamic graft preservation using MP at different temperatures(hypothermia at 4 ℃, normothermia a t 3 7 ℃ and subnormothermia at 20 ℃- 2 5 ℃). Finally, we highlight some emerging applications of regenerative medicine in liver graft preservation. In conclusion, this review discusses the "state of the art" and future perspectives in static and dynamic liver graft preservation in order to improve graft viability.
基金supported by the National Natural Science Foundation of China(31672303 to C.Y.,31660617 to L.W.and 31472013 and 31772453 to W.L.)
文摘Several previous studies have indicated that nest sanitation behavior is a general adaptation in altricial birds,with egg recog nition capacity evolvi ng as a specific response to in terspecific brood parasitism(IBP).However,a rece nt study suggested an alternative hypothesis,con cludi ng that con specific brood parasitism(CBP)selects for egg rejection in thrushes,with IBP as a by-product.In the present study,we used a spectrophotometer to quantify egg coloration and egg mimicry and performed artificial parasitism experiments in the grey?backed thrush(Turdus hortulorum).We showed that individuals of this species rejected 100%of 12 foreign eggs,without IBP or CBP detected.In a review of previous studies,we also discuss possible explanations for the high egg rejection rate in the grey-backed thrush and suggest areas for future study.Altricial birds have evolved advaneed reproductive behavior to in crease the fitn ess of their offspring by buildi ng elaborate structures(i.e.,nests),in which they lay eggs and rear their nestlings(Hansell,2000).Bird nests not only provide a suitable place for nestling development,but also act as a concealed location for safety from predators.Furthermore,bird parents have evolved nest sanitation behavior to clean foreig n objects from their n ests,in eluding feces,eggshells,branches,and leaves,because they induce predation,facilitate microorganism growth,damage eggs,or hurt nestlings during brooding(Guigueno&Sealy,2012).Therefore,nest sanitation has evolved as a general behavior in altricial birds for distinguishing between egg-shaped and non-egg-shaped objects.
基金supported by the National Natural Science Foundation of China(Nos.31672303 to CY,31472013 and 31772453 to WL)
文摘Background:Floods and other extreme events have disastrous effects on wetland breeding birds.However,such events and their consequences are difficult to study due to their rarity and unpredictable occurrence.Methods:Here we compared nest-sites chosen by Reed Parrotbills(Paradoxornis heudei) during June-August 2016 in Yongnianwa Wetlands,Hebei Province,China,before and after an extreme flooding event.Results:Twenty-three nests were identified before and 13 new nests after the flood.There was no significant difference in most nest-site characteristics,such as distance from the road,height of the reeds in which nests were built,or nest volume before or after the flood.However,nests after the flood were located significantly higher in the vegetation compared to before the flood(mean ± SE:1.17 ± 0.13 m vs.0.75 ± 0.26 m,p < 0.01).However,predation rate also increased significantly after the flood(67% vs.25%,p = 0.030).Conclusions:Our results suggested that Reed Parrotbills demonstrated behavioral plasticity in their nest-site selection.Thus,they appeared to increase the height of their nests in response to the drastically changing water levels in reed wetlands,to reduce the likelihood that their nests would be submerged again by flooding.However,predation rate also increased significantly after the flood,suggesting that the change in nest height to combat the threat of flooding made the nests more susceptible to other threats,such as predation.Animals' response to rare climatic events,such as flooding,may produce ecological traps if they make the animals more susceptible to other kinds of threats they are more likely to continue to encounter.
文摘It is well known that balance control is affected by aging, neurological and orthopedic conditions. Poor balance control during gait and postural maintenance are associated with disability, falls and increased mortality. Gait initiation-the transient period between the quiet standing posture and steady state walking-is a functional task that is classically used in the literature to investigate how the central nervous system(CNS) controls balance during a whole-body movement involving change in the base of support dimensions and center of mass progression. Understanding how the CNS in able-bodied subjects exerts this control during such a challenging task is a prerequisite to identifying motor disorders in populations with specific impairments of the postural system. It may also provide clinicians with objective measures to assess the efficiency of rehabilitation programs and better target interventions according to individual impairments. The present review thus proposes a state-of-the-art analysis on:(1) the balance control mechanisms in play during gait initiation in able bodied subjects and in the case of some frail populations; and(2) the biomechanical parameters used in the literature to quantify dynamic stability during gait initiation. Balance control mechanisms reviewed in this article included anticipatory postural adjustments, stance leg stiffness, foot placement, lateral ankle strategy, swing foot strike pattern and vertical center of mass braking. Based on this review, the following viewpoints were put forward:(1) dynamic stability during gait initiation may share a principle of homeostatic regulation similar to most physiological variables, where separate mechanisms need to be coordinated to ensure stabilization of vital variables, and consequently; and(2) rehabilitation interventions which focus on separate or isolated components of posture, balance, or gait may limit the effectiveness of current clinical practices.
文摘Molecular frame photoemission is a very sensitive probe of the photoionization （PI） dynamics of molecules. This paper reports a comparative study of non-resonant and resonant photoionization of D2 induced by VUV circularly polarized synchrotron radiation at SOLEIL at the level of the molecular frame photoelectron angular distributions （MFPADs）. We use the vector correlation method which combines imaging and time-of-flight resolved electron-ion coincidence techniques, and a generalized formalism for the expression of the Ⅰ（χ, θe, Фe） MFPADs, where χ is the orientation of the molecular axis with respect to the light quantization axis and （θe, Фe） the electron emission direction in the molecular frame. Selected MFPADs for a molecule aligned parallel or perpendicular to linearly polarized light, or perpendicular to the propagation axis of circularly polarized light, are presented for dissociative photoionization （DPI） of D2 at two photon excitation energies, hv=19 eV, where direct PI is the only channel opened, and hv=32.5 eV, i.e. in the region involving resonant excitation of Q1 and Q2 doubly excited state series. We discuss in particular the properties of the circular dichroism characterizing photoemission in the molecular frame for direct and resonant PI. In the latter case, a remarkable behavior is observed which may be attributed to the interference occurring between undistinguishable autoionization decay channels.
文摘Climate change has advanced the phenology of many organisms. Migratory animals face particular problems because climate change in the breeding and the wintering range may be asynchronous, preventing rapid response to changing conditions. Advancement in timing of spring migration may have carry-over effects to other parts of the annual cycle, simply because advancement of one event in the annual cycle also advances subsequent events, gradually causing a general shift in the timing of the entire annual cycle. Such a phenotypic shift could generate accumulating effects over the years for individuals, but also across generations. Here we test this novel hypothesis of phenotypic response to climate change by using long-term data on the Arctic tern Sterna paradisaea. Mean breeding date advanced by almost three weeks during the last 70 years. Annual arrival date at the breeding grounds during a period of 47 years was predicted by environmental conditions in the winter quarters in the Southern Ocean near the Antarctic and by mean breeding date the previous year. Annual mean breeding date was only marginally determined by timing of arrival the current year, but to a larger extent by arrival date and breeding date the previous year. Learning affected arrival date as shown by a positive correlation between arrival date in year （i ＋ 1） relative to breeding date in year （i） and the selective advantage of early breeding in year （i）. This provides a mechanism for changes in arrival date being adjusted to changing environmental conditions. This study suggests that adaptation to changing climatic conditions can be achieved through learning from year to year
文摘The use of a broadband, frequency shaped femtosecond laser on translationally cold cesium molecules has recently demonstrated to be a very efficient method of cooling also the vibrational degree of freedom. A sample of cold molecules, initially distributed over several vibrational levels, has thus been transfered into a single selected vibrational level of the singlet X^1∑g ground electronic state. Our method is based on repeated optical pumping by laser light with a spectrum broad enough to excite all populated vibrational levels but limited in its frequency bandwidth with a spatial light modulator. In such a way we are able to eliminate transitions from the selected level, in which molecules accumulate. In this paper we briefly report the main experimental results and then address, in a detailed way by computer simulations, the perspectives for a ＂complete＂ cooling of the molecules, including also the rotational degree of freedom. Since the pumping process strongly depends on the relative shape of the ground and excited potential curves, ro-vibrational cooling through different excited states is theoretically compared.
基金supported by the Russian Foundation for Basic Research (08-02-00690-a)the Russian Academy of Sciences under the Prograof Basic Research
文摘Absorption spectra of the mixed chain nickelates （（NdxY1-x）2BaNiO5 were measured for different x. Experimentally two evidences for the presence of non-equivalent rare-earth centers （NEREC） were found. First, the linewidths show a very strong broadening for x when the calculated distribution over NEREC is wide. Second, a compficated lineshape of the lowest-frequency line in the region of the 4I9/2→4I1/2 electronic lransition is in good agreement with statistics of NEREC. A simple modeling for the line broadening due to NEREC is suggested.
文摘Background:The uropygial gland is an exocrine gland located above the tail of birds that produces a diverse range of biochemicals.It has been hypothesized to be involved in chemical protection,water-proofing and maintenance of plumage brightness.Although these not necessarily mutually exclusive functions have received some empirical support,there has been little empirical research on the function of water-proofing.Methods:Here we analyzed data for 229 individual eiders(Somateria mollissima)collected by Danish hunters during 2016-2018.Results:The Eider is a sea-duck that spends almost its entire life in sea water emphasizing water-proofing of the plumage.The size of the uropygial gland increased with body mass in males,but not in females,and it increased with age.The size of the uropygial gland decreased during winter. Eiders with small uropygial glands grew their feathers at a fast rate.Eiders with large wing areas had large uropygial glands. Conclusions:These findings are consistent with large uropygial glands playing a role in water-proofing during molt and foraging, but also that uropygial glands may play a role in chemical defense.
文摘Inflammatory bowel disease (IBD) is profoundly associated with extraintestinal manifestations (EIM) that can involve almost every organ in our body. Although the exact etiology of IBD is still poorly understood, it is generally characterized by an overly aggressive inflammatory response in the intestinal mucosa. Renal damage is one of the manifestations encountered in Crohn’s disease (CD) and ulcerative colitis (UC) and it accounts for 4% - 23% of IBD patients. The common renal complications of IBD include: glomerulonephritis, tubulointerstitial nephritis, nephrolithiasis, amyloidosis and iatrogenic complications of IBD treatment. Several hypotheses have emerged to explain the pathogenic mechanisms underlying the prevalence of IBD-induced kidney injuries. The present work aims to elucidate the pathological principles that drive secondary renal injury in individuals with IBD and highlight the currently used therapeutic strategies for evaluating, monitoring and treating kidney complications-related IBD.
文摘AIM To evaluate the relationship between the state of transplanted liver graft and the recipient quality of life(QOL) of histologically proven lesions in a 10-year post liver transplantation(LT) cohort of patients. METHODS Seventy-two recipients with a functional first graft at 10 years post-LT underwent liver biopsy and completed a QOL questionnaire. Logistic regression analysis was used to explore associations between histological, clinical andQOL criteria. RESULTS Ten years after LT, fibrosis was detected in 53% of patients, and affected the general health perception, while ductopenia, present in 36%, affected the well-being(P = 0.05). Hepatic steatosis(HS) was present in 33% of patients and was associated with the worst QOL score on multiple domains. When compared to patients without HS, patients with HS had significantly higher incidence of fibrosis(P = 0.03), hepatitis C virus(HCV) infection(P = 0.007), and more patients had retired from their job(P = 0.03). Recurrent or de novo HCV-associated fibrosis and patient retirement as objective variables, and abdominal pain or discomfort and joint aches or pains as subjective variables, emerged as independent determinants of HS. CONCLUSION Long-term liver graft lesions, mainly HS presumably as a surrogate marker of HCV infection, may have a substantial impact on QOL 10 years after LT.
文摘Picosecond pulse radiolysis of neat tetrahydrofuran (THF) shows a fast decay of the solvated electron within 2.5ns.The decay of the solvated electron observed at 790nm is because of spur reaction.A numerical simulation using time dependent Smoluchowski equation containing a sink term with a distance dependent reaction rate is used to fit the pulse-probe data and shows that the geminate reaction can proceed at long distance in this low polar solvent.
文摘There are mainly two approaches to the multifractal analysis of measures. The first one,which is used in applications and in studying problems arising from dynamical systems,uses a hierarchy of boxes. The second one,which is more satisfactory from the viewpoint of geometric measure theory,uses more intrinsic concepts. This article is an account of a work by J.Barral,F.Ben Nasr,and J.Peyriére [3] which provides a bridge between these two theories.
基金Supported by the National Key Basic Research Programme of China under Grant No 2007CB815000, the National Natural Science Foundation of China under Grant Nos 10435010, 10775004 and 10221003.
文摘The single-particle spectrum obtained from the relativistic mean field （RMF） theory is used to extract the shell correction energy with the Strutinsky method. Considering the delicate balance between the plateau condition in the Strutinsky smoothing procedure and the convergence for the total binding energy, the proper space sizes used in solving the RMF equations are investigated in detail by taking ^208 Pb as an example. With the proper space sizes, almost the same shell correction energies are obtained by solving the RMF equations either on basis space or in coordinate space.
文摘Background: Feathers are a defining feature of birds with multiple functions such as flight, insulation, protection against predation and signaling. Feathers are lost during the annual molt while the rate of such loss at other times of the year and its fitness consequences remain poorly known.Methods: I used information on the number and the mass of feathers for 160 individuals belonging to 85 species of birds in general linear mixed models to analyze allometry of feathers and to investigate possible factors explaining variation in the number of feathers. A phylogenetic effect was assessed by quantifying the random effect of genus.Results: The total mass of feathers increased isometrically with body mass, while the total number of feathers and the mean mass of feathers showed negative allometry. Negative allometry implied that small-sized species had relatively many small feathers. There was a negative association between the number of feathers and migration distance. The total number of feathers initially increased during fall and winter, consistent with individuals growing more feathers later during the year or with individuals with fewer feathers selectively disappearing from the population. In contrast, the number of feathers decreased from winter through spring and summer.Conclusions: These findings suggest that thermoregulation has affected the evolution of the number and the size of feathers, there is selection against feather loss, and that the number of feathers varies across seasons.
文摘The molar extinction coefficients at the absorption maximum of the solvated electron spectrum have been evaluated to be 900,970,and 1000 mol^(-1).m^2 for 1,2-ethanediol (12ED),1,2-propanediol (12PD),and 1,3-propanediol (13PD),respectively.These values are two-third or three-fourth of the value usually reported in the published report. Picosecond pulse radiolysis studies have aided in depicting the radiolytic yield of the solvated electron in these sol- vents as a function of time from picosecond to microsecond.The radiolytic yield in these viscous solvents is found to be strongly different from that of the water solution.The temperature dependent absorption spectra of the solvated electron in 12ED,12PD,and 13PD have been also investigated.In all the three solvents,the optical spectra shift to the red with increasing temperature.While the shape of the spectra does not change in 13PD,a widening on the blue side of the absorption band is observed in 12ED and 12PD at elevated temperatures.
