In the common theory of the Universe, the redshift of the light wavelength from distant stars indicates the speed of the star. In this study, the model of the Universe is the surface volume of the four-dimensional sph...In the common theory of the Universe, the redshift of the light wavelength from distant stars indicates the speed of the star. In this study, the model of the Universe is the surface volume of the four-dimensional sphere, and the shape of the Universe results in the most of the redshift of light wavelength. Therefore, there is no dark energy accelerating the Universe. The surface of the four-dimensional sphere is a volume, and this volume is a good model for the Universe. The surface volume of the four-dimensional sphere has been explained by a model of four-dimensional cube, within which the forming of surface volume can be easily shown. The model of four-dimensional cube containing six side cubes is ingenious for explaining the structure of the four-dimensional Universe, but it is not enough because the four-dimensional cube has not six side cubes, but eight side cubes. Therefore, in this study a better method has been created to construct the four-dimensional cube. Our three-dimensional Universe is the surface of the four-dimensional sphere Universe. The volume of our three-dimensional Universe is finite, and beneath it is the infinite volume four-dimensional Super Universe. Two important basic formulae have been derived: The surface volume of the four-dimensional sphere is π<sup>3</sup>R<sup>3</sup> in which R is the radius of the sphere, and the fourth-power volume of the four-dimensional sphere is 1/4 π<sup>3</sup>R<sup>4</sup>. The volume of the Universe has been calculated π<sup>3</sup>R<sup>3</sup> = 62 × 10<sup>30</sup> ly<sup>3</sup>. Time as the fourth dimension of the space takes effect only near the speed of light, and therefore it has been ignored in this study.展开更多
This research aimed to examine the diagnostic accuracy and clinical significance of endoscopic ultrasonography(EUS)in the context of small rectal neuroendocrine neoplasms(NENs).A total of 108 patients with rectal sube...This research aimed to examine the diagnostic accuracy and clinical significance of endoscopic ultrasonography(EUS)in the context of small rectal neuroendocrine neoplasms(NENs).A total of 108 patients with rectal subepithelial lesions(SELs)with a diameter of<20 mm were included in the analysis.The diagnosis and depth assessment of EUS was compared to the histology findings.The prevalence of NENs in rectal SELs was 78.7%(85/108).The sensitivity of EUS in detecting rectal NENs was 98.9%(84/85),while the specificity was 52.2%(12/23).Overall,the diagnostic accuracy of EUS in identifying rectal NENs was 88.9%(96/108).The overall accuracy rate for EUS in assessing the depth of invasion in rectal NENs was 92.9%(78/84).Therefore,EUS demonstrates reasonable diagnostic accuracy in detecting small rectal NENs,with good sensitivity but inferior specificity.EUS may also assist physicians in assessing the depth of invasion in small rectal NENs before endoscopic excision.展开更多
BACKGROUND It is possible that this condition will lead to urosepsis and progressive deterioration of renal function in the absence of surgical intervention.Several recent clinical studies have shown that multi-tract ...BACKGROUND It is possible that this condition will lead to urosepsis and progressive deterioration of renal function in the absence of surgical intervention.Several recent clinical studies have shown that multi-tract percutaneous nephrolithotomy(MPCNL)has a similar stone free rate(SFR)as standard percutaneous nephrolithotomy(S-PCNL).As a result,M-PCNL was also recommended as a treatment option for staghorn calculi.AIM To examine the perioperative and long-term results of ultrasonography-guided single-and M-PCNL.METHODS This was a retrospective cohort study.Between March 2021 and January 2022,the urology department of our hospital selected patients for the treatment of staghorn calculi using percutaneous nephrolithotomy.The primary outcomes were com plication rate and SFR,and the characteristics of patients,operative parameters,laboratory measurements were also collected.RESULTS In total,345 patients were enrolled in the study(186 in the S-PCNL group and 159 in the M-PCNL group).The SFR in the M-PCNL group was significantly higher than that in the S-PCNL group(P=0.033).Moreover,the incidence rates of hydrothorax(P=0.03)and postoperative infection(P=0.012)were higher in the M-PCNL group than in the S-PCNL group.Logistic regression analysis demonstrated that post-operative white blood cell count(OR=2.57,95%CI:1.90-3.47,P<0.001)and stone size(OR=1.59,95%CI:1.27-2.00,P<0.001)were associated with a higher overall complication rate in the S-PCNL group.Body mass index(OR=1.22,95%CI:1.06-1.40,P=0.004)and stone size(OR=1.70,95%CI:1.35-2.15,P<0.001)were associated with increased overall complications in the M-PCNL group.CONCLUSION Multiple access tracts can facilitate higher SFR while slightly increasing the incidence of acceptable complications.展开更多
BACKGROUND The incidence of gastric cancer remains high,and it is the sixth most common cancer and the fourth leading cause of cancer deaths worldwide.Oral contrastenhanced ultrasonography is a simple,non-invasive,and...BACKGROUND The incidence of gastric cancer remains high,and it is the sixth most common cancer and the fourth leading cause of cancer deaths worldwide.Oral contrastenhanced ultrasonography is a simple,non-invasive,and painless method for the diagnosis of gastric tumors.AIM To explore the diagnostic value of oral contrast-enhanced ultrasonography for the detection of gastric tumors.METHODS The screening results based on oral contrast-enhanced ultrasonography and electronic gastroscopy were compared with those of the postoperative pathological examination.RESULTS Among 42 patients with gastric tumors enrolled in the study,the diagnostic accordance rate was 95.2%for oral contrast-enhanced ultrasonography(n=40)and 90.5%for electronic gastroscopy(n=38)compared with postoperative pathological examination.The Kappa value of consistency test with pathological findings was 0.812 for oral contrast-enhanced ultrasonography and 0.718 for electronic gastroscopy,and there was no significant difference between them(P=0.397).For the TNM staging of gastric tumors,the accuracy rate of oral contrast enhanced ultrasonography was 81.9%for the overall T staging and 50%,77.8%,100%,and 100%for T1,T2,T3,and T4 staging,respectively.The sensitivity and specificity were both 100%for stages T3 and T4.The diagnostic accuracy rate of oral contrast-enhanced ultrasonography was 93.8%,80%,100%,and 100%for stages N0,N1-N3,M0,and M1,respectively.CONCLUSION The accordance rate of qualitative diagnosis by oral contrast-enhanced ultrasonography is comparable to that of gastroscopy,and it could be used as the preferred method for the early screening of gastric tumors.展开更多
BACKGROUND Superior mesenteric artery(SMA)syndrome is a rare cause of duodenal obstruction by extrinsic compression between the SMA and the aorta(SMA-Ao).Although the left lateral recumbent position is considered effe...BACKGROUND Superior mesenteric artery(SMA)syndrome is a rare cause of duodenal obstruction by extrinsic compression between the SMA and the aorta(SMA-Ao).Although the left lateral recumbent position is considered effective in the treatment of SMA syndrome,individual variations in the optimal patient position have been noted.In this report,we present two elderly cases of SMA syndrome that exhibited rapid recovery due to ultrasonographic dynamic evaluation of the optimal position for each patient.CASE SUMMARY Case 1:A 90-year-old man with nausea and vomiting.Following diagnosis of SMA syndrome by computed tomography(CT),ultrasonography(US)revealed the SMA-Ao distance in the supine position(4 mm),which slightly improved in the lateral position(5.7–7.0 mm)without the passage of duodenal contents.However,in the sitting position,the SMA-Ao distance was increased to 15 mm accompanied by improved content passage.Additionally,US indicated enhanced passage upon abdominal massage on the right side.By day 2,the patient could eat comfortably with the optimal position and massage.Case 2:An 87-year-old woman with vomiting.After the diagnosis of SMA syndrome and aspiration pneumonia by CT,dynamic US confirmed the optimal position(SMA-Ao distance was improved to 7 mm in forward-bent position,whereas it remained at 5 mm in the supine position).By day 7 when her pneumonia recovered,she could eat with the optimal position.CONCLUSION The optimal position for SMA syndrome varies among individuals.Dynamic US appears to be a valuable tool in improving patient outcomes.展开更多
Point of care ultrasonography(POCUS)has evolved to become the fifth pillar of the conventional physical examination,and use of POCUS protocols have significantly decreased procedure complications and time to diagnose....Point of care ultrasonography(POCUS)has evolved to become the fifth pillar of the conventional physical examination,and use of POCUS protocols have significantly decreased procedure complications and time to diagnose.However,lack of experience in POCUS by preceptors in medical schools and nephrology residency programs are significant barriers to implement a broader use.In rural and low-income areas POCUS may have a transformative effect on health care management.展开更多
Esophageal tuberculosis(ET)is a relatively rare clinical condition,characterized by often atypical clinical features.The lack of specificity in diagnostic methods,such as esophagogastroduodenoscopy and various imaging...Esophageal tuberculosis(ET)is a relatively rare clinical condition,characterized by often atypical clinical features.The lack of specificity in diagnostic methods,such as esophagogastroduodenoscopy and various imaging techniques,frequently leads to misdiagnosis and inappropriate treatments.Compared to esophagogastroduodenoscopy,endoscopic ultrasonography(EUS)offers a more comprehensive examination of esophageal tuberculosis lesions,including the extent of wall layer involvement and the internal structure characteristics of the lesions.Furthermore,when necessary,endoscopic ultrasonography-guided fine-needle aspiration can be employed to acquire deeper pathological tissue,significantly aiding diagnosis.When combined with the patient’s clinical presentation,endoscopic findings,and pathological features,EUS plays a crucial role in the definitive diagnosis of ET and in the differential diagnosis process.This article meticulously reviews both national and international literature to summarize the relevant features of ET,with a focus on its appearance under EUS,and to highlight the clinical value of EUS in enhancing the diagnosis of ET and in distinguishing it from other conditions.The aim is to offer guidance for the accurate diagnosis of ET.展开更多
Aircraft ground movement plays a key role in improving airport efficiency,as it acts as a link to all other ground operations.Finding novel approaches to coordinate the movements of a fleet of aircraft at an airport i...Aircraft ground movement plays a key role in improving airport efficiency,as it acts as a link to all other ground operations.Finding novel approaches to coordinate the movements of a fleet of aircraft at an airport in order to improve system resilience to disruptions with increasing autonomy is at the center of many key studies for airport airside operations.Moreover,autonomous taxiing is envisioned as a key component in future digitalized airports.However,state-of-the-art routing and scheduling algorithms for airport ground movements do not consider high-fidelity aircraft models at both the proactive and reactive planning phases.The majority of such algorithms do not actively seek to optimize fuel efficiency and reduce harmful greenhouse gas emissions.This paper proposes a new approach for generating efficient four-dimensional trajectories(4DTs)on the basis of a high-fidelity aircraft model and gainscheduling control strategy.Working in conjunction with a routing and scheduling algorithm that determines the taxi route,waypoints,and time deadlines,the proposed approach generates fuel-efficient 4DTs in real time,while respecting operational constraints.The proposed approach can be used in two contexts:①as a reactive decision support tool to generate new trajectories that can resolve unprecedented events;and②as an autopilot system for both partial and fully autonomous taxiing.The proposed methodology is realistic and simple to implement.Moreover,simulation studies show that the proposed approach is capable of providing an up to 11%reduction in the fuel consumed during the taxiing of a large Boeing 747-100 jumbo jet.展开更多
A new four-dimensional quadratic smooth autonomous chaotic system is presented in this paper,which can exhibit periodic orbit and chaos under the conditions on the system parameters.Importantly,the system can generate...A new four-dimensional quadratic smooth autonomous chaotic system is presented in this paper,which can exhibit periodic orbit and chaos under the conditions on the system parameters.Importantly,the system can generate one-,two-,three-and four-scroll chaotic attractors with appropriate choices of parameters.Interestingly,all the attractors are generated only by changing a single parameter.The dynamic analysis approach in the paper involves time series,phase portraits,Poincar'e maps,a bifurcation diagram,and Lyapunov exponents,to investigate some basic dynamical behaviours of the proposed four-dimensional system.展开更多
Since its introduction in the 1970’s,magnetic resonance imaging(MRI)has become a standard imaging modality.With its broad and standardized application,it is firmly established in the clinical routine and an essential...Since its introduction in the 1970’s,magnetic resonance imaging(MRI)has become a standard imaging modality.With its broad and standardized application,it is firmly established in the clinical routine and an essential element in cardiovascular and abdominal imaging.In addition to sonography and computer tomography,MRI is a valuable tool for diagnosing cardiovascular and abdominal diseases,for determining disease severity,and for assessing therapeutic success.MRI techniques have improved over the last few decades,revealing not just morphologic information,but functional information about perfusion,diffusion and hemodynamics as well.Four-dimensional(4D)flow MRI,a time-resolved phase contrast-MRI with three-dimensional(3D)anatomic coverage and velocity encoding along all three flow directions has been used to comprehensively assess complex cardiovascular hemodynamics in multiple regions of the body.The technique enables visualization of 3D blood flow patterns and retrospective quantification of blood flow parameters in a region of interest.Over the last few years,4D flow MRI has been increasingly performed in the abdominal region.By applying different acceleration techniques,taking 4D flow MRI measurements has dropped to a reasonable scanning time of 8 to 12 min.These new developments have encouraged a growing number of patient studies in the literature validating the technique’s potential for enhanced evaluation of blood flow parameters within the liver’s complex vascular system.The purpose of this review article is to broaden our understanding of 4D flow MRI for the assessment of liver hemodynamics by providing insights into acquisition,data analysis,visualization and quantification.Furthermore,in this article we highlight its development,focussing on the clinical application of the technique.展开更多
Cross-cultural management is often regarded as a discipline of international management focusing on cultural encounters between the organization and the nation-state, and providing tools to tackle cultural difl＇erenc...Cross-cultural management is often regarded as a discipline of international management focusing on cultural encounters between the organization and the nation-state, and providing tools to tackle cultural difl＇erences seen as sources of conflict, friction or misunderstanding. Based on Greet Hofstede＇ s Cultural Model, this paper attempts to shed some light on effective corporation management through cultural analysis of the difl＇erences between China and western countries. The paper puts more emphasis on the impact of cultural compatibility on effective corporation man- agement through the case study of China, Japan, Germany and America. The author argues that managers and employ- ees involved in companies with diverse cultural backgrounds should be integrated and developed into a specific local context through interlocking their cultural identifications and the organizational practices.展开更多
Carbon, hydrogen, oxygen, nitrogen, sulfur, and their compounds are volatile components that dominate the thin and fragile atmosphere, hydrosphere, and biosphere on Earth’s habitable surface. However, the vast majori...Carbon, hydrogen, oxygen, nitrogen, sulfur, and their compounds are volatile components that dominate the thin and fragile atmosphere, hydrosphere, and biosphere on Earth’s habitable surface. However, the vast majority of these volatiles are hidden in the deep interior, where the high pressure–temperature conditions drastically and categorically alter the physics and chemistry of the volatiles. Like the bloodstream of an organism, the circulations and interactions of volatiles in the deep Earth modulate climate, resources, energy, natural hazards, and other factors that define the Earth as a unique living and changing planet.展开更多
The problem addressed is the exact determination of the operator norm and lower bound of four-dimensional generalized Hausdorff matrices on the double sequence spaces L_(p).A Hardy type formulae is found as an exact v...The problem addressed is the exact determination of the operator norm and lower bound of four-dimensional generalized Hausdorff matrices on the double sequence spaces L_(p).A Hardy type formulae is found as an exact value for their operator norm and a Copson type formulae is established as a lower estimate for their lower bound.Further,exact values are found for the operator norm and lower bound of the transpose of generalized Hausdorff matrices.展开更多
Objective:To determine whether cervical ultrasonography,magnetic resonance imaging(MRI),and magnetic resonance angiography(MRA)are useful in the differential diagnosis of etiology and understanding the pathophysiology...Objective:To determine whether cervical ultrasonography,magnetic resonance imaging(MRI),and magnetic resonance angiography(MRA)are useful in the differential diagnosis of etiology and understanding the pathophysiology in cases of apogeotropic direction-changing positional nystagmus(DCPN).Methods:Thirty patients with apogeotropic DCPN were classified into 11 cases of central disease,seven cases of mixed central and peripheral disease,and 12 cases of peripheral disease by differential diagnosis based on various balance function,neuro-otological,and imaging tests.Cervical ultrasonography using the cervical rotation method and MRI and MRA of the head and neck were performed in most patients with apogeotropic DCPN.We reviewed the presence of abnormal imaging findings according to the disease etiology.Results:Of the 30 patients with apogeotropic DCPN,23 showed vascular abnormalities or central lesions on imaging.Vascular lesions were found in six of the 12 patients with peripheral disease.Cervical ultrasonography with cervical rotation detected blood flow disturbance in the vertebral artery in eight patients in whom the disturbance could not be detected by MRI or MRA of the head and neck.Discussion:We hypothesize that the causative disease of apogeotropic DCPN may be strongly associated with circulatory insufficiency of the vertebrobasilar and carotid arteries,and that impaired blood flow in these vessels may affect peripheral vestibular and central function.In patients with apogeotropic DCPN,examinations of vestibular function,central nervous system symptoms,and brain hemodynamics are valuable for differential diagnosis.展开更多
Objective:To explore the value of four-dimensional spatiotemporal image correlation and tomographic ultrasound imaging in screening fetal congenital heart disease.Methods: A total of 671 pregnant women at 22-24 gestat...Objective:To explore the value of four-dimensional spatiotemporal image correlation and tomographic ultrasound imaging in screening fetal congenital heart disease.Methods: A total of 671 pregnant women at 22-24 gestational weeks from January 2018 to December 2018 were examined by two-dimensional ultrasound and four-dimensional spatiotemporal image correlation and tomographic ultrasound imaging to observe the development of fetal cardiovascular structure and to compare the two methods in terms of diagnostic accuracy, examination time, image quality and new physician training cycle.Results: Cardiac malformations were found in 12 of the 671 fetuses, among which 11 cases were detected by four-dimensional spatiotemporal image correlation and tomographic ultrasound imaging and 1 case was missed. Postnatal echocardiographic reexamination and autopsy confirmed 12 cases of children with cardiac malformation, including 1 case of atrial septal defect (missed diagnosis by four-dimensional spatiotemporal image correlation and tomographic ultrasound imaging), 4 cases of tetralogy of Fallot's disease, 1 case of right ventricular double outlet, 3 cases of left ventricular dysplasia, 2 cases of complete transposition of the great artery and 1 case of tricuspid valve descending malformation. There was no statistically significant difference between four-dimensional spatiotemporal image correlation and tomographic ultrasound imaging and conventional two-dimensional color echocardiography or/and autopsy (P>0.05). In terms of examination time and new physician training, the four-dimensional spatiotemporal image correlation and tomographic ultrasound imaging technique was superior to conventional color ultrasound screening. No statistically significant difference in image quality.Conclusions:The four-dimensional spatiotemporal image correlation and tomographic ultrasound imaging can rapidly and accurately display fetal heart development, and can be used as the main screening method for fetal congenital heart disease in clinical practice.展开更多
Objective:To research the effect of four-dimensional therapy on the clinical effect (symptoms, blood pressure, and pain degree), the changes of blood rheology and arterial (left vertebral artery (LVA), right vertebral...Objective:To research the effect of four-dimensional therapy on the clinical effect (symptoms, blood pressure, and pain degree), the changes of blood rheology and arterial (left vertebral artery (LVA), right vertebral artery (RVA), and basal artery (BA)) hemodynamics (average cerebral blood flow (Vm), resistance index (RI), pulsatility index (PI)) on patients with cervical hypertension. Method: Selecting 120 patients (Department of Orthopaedics, the second Affiliated Hospital to Liaoning University of Chinese Medicine, 2012.6-2018.10) with cervical hypertension, then they were divided into observation group (n=60) and control group (n=60). The control group were given enalapril meleate (amlodipine besylate) +conventional therapy (acupuncture treatment and massage), the observation group were given four-dimensional therapy on the basic of control group, they were treated 3 weeks. The primary endpoints were the changes from baseline to week 3 in the symptoms and function were scored using the Evaluation Scale for Cervical Vertigo, the secondary endpoints were changes from baseline to month 3 in the artery hemodynamics (Vm, RI, and PI) in the BA, LVA, blood rheology, and RVA. At last, assessing the pain degree through visual analog scale (VAS), measuring the blood pressure, and accessing the clinical effect.Results:The score of vertigo in the two groups had no statistical significance before treatment, the score of vertigo in the two groups were higher than pretherapy, and had statistical significance, and the score in the observation group were higher than control group, and had statistical significance. The hemodynamics (Vm, RI, and PI) in the artery (BA, LVA, and RVA) had no statistical significance in the two groups before treatment, and the hemodynamics (Vm) in the artery (BA, LVA, and RVA) were higher than pretherapy, and had statistical significance, the hemodynamics (Vm) in the artery (BA, LVA, and RVA) of observation group were higher than control group, and had statistical significance. The hemodynamics (RI and PI) in the artery (BA, LVA, and RVA) were lower than pretherapy, and had statistical significance, the the hemodynamics (Vm) in the artery (BA, LVA, and RVA) of observation group were lower than control group, and had statistical significance. The blood rheology had no statistical significance in the two groups before treatment, the blood rheology were lower than pretherapy, and had statistical significance, the blood rheology of observation group were lower than control group, and had statistical significance. The degree of VAS had no statistical significance in the two groups before treatment, the degree of VAS was lower than pretherapy, and had statistical significance, the degree of VAS of observation group were lower than control group, and had statistical significance. The blood pressure (systolic pressure and diastolic pressure) had no statistical significance in the two groups before treatment, the blood pressure (systolic pressure and diastolic pressure) were lower than pretherapy, and had statistical significance, the blood pressure (systolic pressure and diastolic pressure) of observation group were lower than control group, and had statistical significance, the clinical effect in the observation group were higher than control group, and had statistical significance.Conclusions:Giving four-dimensional therapy can improve the blood pressure and relieve the pain through improving blood rheology and hemodynamics in the artery in the patients with cervical hypertension.展开更多
In this manuscript, Local dynamic behaviors including stability and Hopf bifurcation of a new four-dimensional quadratic autonomous system are studied both analytically and numerically. Determining conditions of equil...In this manuscript, Local dynamic behaviors including stability and Hopf bifurcation of a new four-dimensional quadratic autonomous system are studied both analytically and numerically. Determining conditions of equilibrium points on different parameters are derived. Next, the stability conditions are investigated by using Routh-Hurwitz criterion and bifurcation conditions are investigated by using Hopf bifurcation theory, respectively. It is found that Hopf bifurcation on the initial point is supercritical in this four-dimensional autonomous system. The theoretical results are verified by numerical simulation. Besides, the new four-dimensional autonomous system under the parametric conditions of hyperchaos is studied in detail. It is also found that the system can enter hyperchaos, first through Hopf bifurcation and then through periodic bifurcation.展开更多
The four-dimensional variational assimilation(4D-Var)has been widely used in meteorological and oceanographic data assimilation.This method is usually implemented in the model space,known as primal approach(P4D-Var).A...The four-dimensional variational assimilation(4D-Var)has been widely used in meteorological and oceanographic data assimilation.This method is usually implemented in the model space,known as primal approach(P4D-Var).Alternatively,physical space analysis system(4D-PSAS)is proposed to reduce the computation cost,in which the 4D-Var problem is solved in physical space(i.e.,observation space).In this study,the conjugate gradient(CG)algorithm,implemented in the 4D-PSAS system is evaluated and it is found that the non-monotonic change of the gradient norm of 4D-PSAS cost function causes artificial oscillations of cost function in the iteration process.The reason of non-monotonic variation of gradient norm in 4D-PSAS is then analyzed.In order to overcome the non-monotonic variation of gradient norm,a new algorithm,Minimum Residual(MINRES)algorithm,is implemented in the process of assimilation iteration in this study.Our experimental results show that the improved 4D-PSAS with the MINRES algorithm guarantees the monotonic reduction of gradient norm of cost function,greatly improves the convergence properties of 4D-PSAS as well,and significantly restrains the numerical noises associated with the traditional 4D-PSAS system.展开更多
The present letter to the editor is related to the work entitled“Large leiomyoma of lower esophagus diagnosed by endoscopic ultrasonography-fine needle aspiration:A case report.”Although endoscopic ultrasonography s...The present letter to the editor is related to the work entitled“Large leiomyoma of lower esophagus diagnosed by endoscopic ultrasonography-fine needle aspiration:A case report.”Although endoscopic ultrasonography seems necessary in a suspected leiomyoma of the esophagus,the performance of biopsies via fine needle aspiration is controversial as it increases the risk of complications such as bleeding,infection,and intraoperative perforations.Laparoscopy is the best treatment strategy for small tumors.Laparotomy with tumor enucleation or esophageal resection can be considered in large leiomyomas.展开更多
BACKGROUND Omental infarction(OI)is a surgical abdominal disease that is not common in adults and is very rare in children.Similar to various acute abdominal pain diseases including appendicitis,diagnosis was previous...BACKGROUND Omental infarction(OI)is a surgical abdominal disease that is not common in adults and is very rare in children.Similar to various acute abdominal pain diseases including appendicitis,diagnosis was previously achieved by diagnostic laparotomy but more recently,ultrasonography or computed tomography(CT)examination has been used.CASE SUMMARY A 6-year-old healthy boy with no specific medical history visited the emergency room with right lower abdominal pain.He underwent abdominal ultrasonography by a radiologist to rule out acute appendicitis.He was discharged with no significant sonographic finding and symptom relief.However,the symptoms persisted for 2 more days and an outpatient visit was made.An outpatient abdominal CT was used to make a diagnosis of OI.After laparoscopic operation,his symptoms resolved.CONCLUSION In children’s acute abdominal pain,imaging studies should be performed for appendicitis and OI.展开更多
文摘In the common theory of the Universe, the redshift of the light wavelength from distant stars indicates the speed of the star. In this study, the model of the Universe is the surface volume of the four-dimensional sphere, and the shape of the Universe results in the most of the redshift of light wavelength. Therefore, there is no dark energy accelerating the Universe. The surface of the four-dimensional sphere is a volume, and this volume is a good model for the Universe. The surface volume of the four-dimensional sphere has been explained by a model of four-dimensional cube, within which the forming of surface volume can be easily shown. The model of four-dimensional cube containing six side cubes is ingenious for explaining the structure of the four-dimensional Universe, but it is not enough because the four-dimensional cube has not six side cubes, but eight side cubes. Therefore, in this study a better method has been created to construct the four-dimensional cube. Our three-dimensional Universe is the surface of the four-dimensional sphere Universe. The volume of our three-dimensional Universe is finite, and beneath it is the infinite volume four-dimensional Super Universe. Two important basic formulae have been derived: The surface volume of the four-dimensional sphere is π<sup>3</sup>R<sup>3</sup> in which R is the radius of the sphere, and the fourth-power volume of the four-dimensional sphere is 1/4 π<sup>3</sup>R<sup>4</sup>. The volume of the Universe has been calculated π<sup>3</sup>R<sup>3</sup> = 62 × 10<sup>30</sup> ly<sup>3</sup>. Time as the fourth dimension of the space takes effect only near the speed of light, and therefore it has been ignored in this study.
基金Supported by Basic and Applied Basic Research Foundation of Guangzhou,No.202201011331National Natural Science Foundation of China,No.82373118Natural Science Foundation of Guangdong Province,No.2023A1515010828.
文摘This research aimed to examine the diagnostic accuracy and clinical significance of endoscopic ultrasonography(EUS)in the context of small rectal neuroendocrine neoplasms(NENs).A total of 108 patients with rectal subepithelial lesions(SELs)with a diameter of<20 mm were included in the analysis.The diagnosis and depth assessment of EUS was compared to the histology findings.The prevalence of NENs in rectal SELs was 78.7%(85/108).The sensitivity of EUS in detecting rectal NENs was 98.9%(84/85),while the specificity was 52.2%(12/23).Overall,the diagnostic accuracy of EUS in identifying rectal NENs was 88.9%(96/108).The overall accuracy rate for EUS in assessing the depth of invasion in rectal NENs was 92.9%(78/84).Therefore,EUS demonstrates reasonable diagnostic accuracy in detecting small rectal NENs,with good sensitivity but inferior specificity.EUS may also assist physicians in assessing the depth of invasion in small rectal NENs before endoscopic excision.
文摘BACKGROUND It is possible that this condition will lead to urosepsis and progressive deterioration of renal function in the absence of surgical intervention.Several recent clinical studies have shown that multi-tract percutaneous nephrolithotomy(MPCNL)has a similar stone free rate(SFR)as standard percutaneous nephrolithotomy(S-PCNL).As a result,M-PCNL was also recommended as a treatment option for staghorn calculi.AIM To examine the perioperative and long-term results of ultrasonography-guided single-and M-PCNL.METHODS This was a retrospective cohort study.Between March 2021 and January 2022,the urology department of our hospital selected patients for the treatment of staghorn calculi using percutaneous nephrolithotomy.The primary outcomes were com plication rate and SFR,and the characteristics of patients,operative parameters,laboratory measurements were also collected.RESULTS In total,345 patients were enrolled in the study(186 in the S-PCNL group and 159 in the M-PCNL group).The SFR in the M-PCNL group was significantly higher than that in the S-PCNL group(P=0.033).Moreover,the incidence rates of hydrothorax(P=0.03)and postoperative infection(P=0.012)were higher in the M-PCNL group than in the S-PCNL group.Logistic regression analysis demonstrated that post-operative white blood cell count(OR=2.57,95%CI:1.90-3.47,P<0.001)and stone size(OR=1.59,95%CI:1.27-2.00,P<0.001)were associated with a higher overall complication rate in the S-PCNL group.Body mass index(OR=1.22,95%CI:1.06-1.40,P=0.004)and stone size(OR=1.70,95%CI:1.35-2.15,P<0.001)were associated with increased overall complications in the M-PCNL group.CONCLUSION Multiple access tracts can facilitate higher SFR while slightly increasing the incidence of acceptable complications.
文摘BACKGROUND The incidence of gastric cancer remains high,and it is the sixth most common cancer and the fourth leading cause of cancer deaths worldwide.Oral contrastenhanced ultrasonography is a simple,non-invasive,and painless method for the diagnosis of gastric tumors.AIM To explore the diagnostic value of oral contrast-enhanced ultrasonography for the detection of gastric tumors.METHODS The screening results based on oral contrast-enhanced ultrasonography and electronic gastroscopy were compared with those of the postoperative pathological examination.RESULTS Among 42 patients with gastric tumors enrolled in the study,the diagnostic accordance rate was 95.2%for oral contrast-enhanced ultrasonography(n=40)and 90.5%for electronic gastroscopy(n=38)compared with postoperative pathological examination.The Kappa value of consistency test with pathological findings was 0.812 for oral contrast-enhanced ultrasonography and 0.718 for electronic gastroscopy,and there was no significant difference between them(P=0.397).For the TNM staging of gastric tumors,the accuracy rate of oral contrast enhanced ultrasonography was 81.9%for the overall T staging and 50%,77.8%,100%,and 100%for T1,T2,T3,and T4 staging,respectively.The sensitivity and specificity were both 100%for stages T3 and T4.The diagnostic accuracy rate of oral contrast-enhanced ultrasonography was 93.8%,80%,100%,and 100%for stages N0,N1-N3,M0,and M1,respectively.CONCLUSION The accordance rate of qualitative diagnosis by oral contrast-enhanced ultrasonography is comparable to that of gastroscopy,and it could be used as the preferred method for the early screening of gastric tumors.
文摘BACKGROUND Superior mesenteric artery(SMA)syndrome is a rare cause of duodenal obstruction by extrinsic compression between the SMA and the aorta(SMA-Ao).Although the left lateral recumbent position is considered effective in the treatment of SMA syndrome,individual variations in the optimal patient position have been noted.In this report,we present two elderly cases of SMA syndrome that exhibited rapid recovery due to ultrasonographic dynamic evaluation of the optimal position for each patient.CASE SUMMARY Case 1:A 90-year-old man with nausea and vomiting.Following diagnosis of SMA syndrome by computed tomography(CT),ultrasonography(US)revealed the SMA-Ao distance in the supine position(4 mm),which slightly improved in the lateral position(5.7–7.0 mm)without the passage of duodenal contents.However,in the sitting position,the SMA-Ao distance was increased to 15 mm accompanied by improved content passage.Additionally,US indicated enhanced passage upon abdominal massage on the right side.By day 2,the patient could eat comfortably with the optimal position and massage.Case 2:An 87-year-old woman with vomiting.After the diagnosis of SMA syndrome and aspiration pneumonia by CT,dynamic US confirmed the optimal position(SMA-Ao distance was improved to 7 mm in forward-bent position,whereas it remained at 5 mm in the supine position).By day 7 when her pneumonia recovered,she could eat with the optimal position.CONCLUSION The optimal position for SMA syndrome varies among individuals.Dynamic US appears to be a valuable tool in improving patient outcomes.
文摘Point of care ultrasonography(POCUS)has evolved to become the fifth pillar of the conventional physical examination,and use of POCUS protocols have significantly decreased procedure complications and time to diagnose.However,lack of experience in POCUS by preceptors in medical schools and nephrology residency programs are significant barriers to implement a broader use.In rural and low-income areas POCUS may have a transformative effect on health care management.
基金This work was supported by Regional Collaborative Innovation Project of Xinjiang Uygur Autonomous Region(2022E02044).
文摘Esophageal tuberculosis(ET)is a relatively rare clinical condition,characterized by often atypical clinical features.The lack of specificity in diagnostic methods,such as esophagogastroduodenoscopy and various imaging techniques,frequently leads to misdiagnosis and inappropriate treatments.Compared to esophagogastroduodenoscopy,endoscopic ultrasonography(EUS)offers a more comprehensive examination of esophageal tuberculosis lesions,including the extent of wall layer involvement and the internal structure characteristics of the lesions.Furthermore,when necessary,endoscopic ultrasonography-guided fine-needle aspiration can be employed to acquire deeper pathological tissue,significantly aiding diagnosis.When combined with the patient’s clinical presentation,endoscopic findings,and pathological features,EUS plays a crucial role in the definitive diagnosis of ET and in the differential diagnosis process.This article meticulously reviews both national and international literature to summarize the relevant features of ET,with a focus on its appearance under EUS,and to highlight the clinical value of EUS in enhancing the diagnosis of ET and in distinguishing it from other conditions.The aim is to offer guidance for the accurate diagnosis of ET.
基金This work was funded by the UK Engineering and Physical Sciences Research Council(EP/N029496/1,EP/N029496/2,EP/N029356/1,EP/N029577/1,and EP/N029577/2).
文摘Aircraft ground movement plays a key role in improving airport efficiency,as it acts as a link to all other ground operations.Finding novel approaches to coordinate the movements of a fleet of aircraft at an airport in order to improve system resilience to disruptions with increasing autonomy is at the center of many key studies for airport airside operations.Moreover,autonomous taxiing is envisioned as a key component in future digitalized airports.However,state-of-the-art routing and scheduling algorithms for airport ground movements do not consider high-fidelity aircraft models at both the proactive and reactive planning phases.The majority of such algorithms do not actively seek to optimize fuel efficiency and reduce harmful greenhouse gas emissions.This paper proposes a new approach for generating efficient four-dimensional trajectories(4DTs)on the basis of a high-fidelity aircraft model and gainscheduling control strategy.Working in conjunction with a routing and scheduling algorithm that determines the taxi route,waypoints,and time deadlines,the proposed approach generates fuel-efficient 4DTs in real time,while respecting operational constraints.The proposed approach can be used in two contexts:①as a reactive decision support tool to generate new trajectories that can resolve unprecedented events;and②as an autopilot system for both partial and fully autonomous taxiing.The proposed methodology is realistic and simple to implement.Moreover,simulation studies show that the proposed approach is capable of providing an up to 11%reduction in the fuel consumed during the taxiing of a large Boeing 747-100 jumbo jet.
文摘A new four-dimensional quadratic smooth autonomous chaotic system is presented in this paper,which can exhibit periodic orbit and chaos under the conditions on the system parameters.Importantly,the system can generate one-,two-,three-and four-scroll chaotic attractors with appropriate choices of parameters.Interestingly,all the attractors are generated only by changing a single parameter.The dynamic analysis approach in the paper involves time series,phase portraits,Poincar'e maps,a bifurcation diagram,and Lyapunov exponents,to investigate some basic dynamical behaviours of the proposed four-dimensional system.
文摘Since its introduction in the 1970’s,magnetic resonance imaging(MRI)has become a standard imaging modality.With its broad and standardized application,it is firmly established in the clinical routine and an essential element in cardiovascular and abdominal imaging.In addition to sonography and computer tomography,MRI is a valuable tool for diagnosing cardiovascular and abdominal diseases,for determining disease severity,and for assessing therapeutic success.MRI techniques have improved over the last few decades,revealing not just morphologic information,but functional information about perfusion,diffusion and hemodynamics as well.Four-dimensional(4D)flow MRI,a time-resolved phase contrast-MRI with three-dimensional(3D)anatomic coverage and velocity encoding along all three flow directions has been used to comprehensively assess complex cardiovascular hemodynamics in multiple regions of the body.The technique enables visualization of 3D blood flow patterns and retrospective quantification of blood flow parameters in a region of interest.Over the last few years,4D flow MRI has been increasingly performed in the abdominal region.By applying different acceleration techniques,taking 4D flow MRI measurements has dropped to a reasonable scanning time of 8 to 12 min.These new developments have encouraged a growing number of patient studies in the literature validating the technique’s potential for enhanced evaluation of blood flow parameters within the liver’s complex vascular system.The purpose of this review article is to broaden our understanding of 4D flow MRI for the assessment of liver hemodynamics by providing insights into acquisition,data analysis,visualization and quantification.Furthermore,in this article we highlight its development,focussing on the clinical application of the technique.
文摘Cross-cultural management is often regarded as a discipline of international management focusing on cultural encounters between the organization and the nation-state, and providing tools to tackle cultural difl＇erences seen as sources of conflict, friction or misunderstanding. Based on Greet Hofstede＇ s Cultural Model, this paper attempts to shed some light on effective corporation management through cultural analysis of the difl＇erences between China and western countries. The paper puts more emphasis on the impact of cultural compatibility on effective corporation man- agement through the case study of China, Japan, Germany and America. The author argues that managers and employ- ees involved in companies with diverse cultural backgrounds should be integrated and developed into a specific local context through interlocking their cultural identifications and the organizational practices.
基金Alfred P. Sloan Foundation (G-2016-7065) to the DCO Secretariatthe National Natural Science Foundation of China (U1530402) to HPSTAR.
文摘Carbon, hydrogen, oxygen, nitrogen, sulfur, and their compounds are volatile components that dominate the thin and fragile atmosphere, hydrosphere, and biosphere on Earth’s habitable surface. However, the vast majority of these volatiles are hidden in the deep interior, where the high pressure–temperature conditions drastically and categorically alter the physics and chemistry of the volatiles. Like the bloodstream of an organism, the circulations and interactions of volatiles in the deep Earth modulate climate, resources, energy, natural hazards, and other factors that define the Earth as a unique living and changing planet.
文摘The problem addressed is the exact determination of the operator norm and lower bound of four-dimensional generalized Hausdorff matrices on the double sequence spaces L_(p).A Hardy type formulae is found as an exact value for their operator norm and a Copson type formulae is established as a lower estimate for their lower bound.Further,exact values are found for the operator norm and lower bound of the transpose of generalized Hausdorff matrices.
文摘Objective:To determine whether cervical ultrasonography,magnetic resonance imaging(MRI),and magnetic resonance angiography(MRA)are useful in the differential diagnosis of etiology and understanding the pathophysiology in cases of apogeotropic direction-changing positional nystagmus(DCPN).Methods:Thirty patients with apogeotropic DCPN were classified into 11 cases of central disease,seven cases of mixed central and peripheral disease,and 12 cases of peripheral disease by differential diagnosis based on various balance function,neuro-otological,and imaging tests.Cervical ultrasonography using the cervical rotation method and MRI and MRA of the head and neck were performed in most patients with apogeotropic DCPN.We reviewed the presence of abnormal imaging findings according to the disease etiology.Results:Of the 30 patients with apogeotropic DCPN,23 showed vascular abnormalities or central lesions on imaging.Vascular lesions were found in six of the 12 patients with peripheral disease.Cervical ultrasonography with cervical rotation detected blood flow disturbance in the vertebral artery in eight patients in whom the disturbance could not be detected by MRI or MRA of the head and neck.Discussion:We hypothesize that the causative disease of apogeotropic DCPN may be strongly associated with circulatory insufficiency of the vertebrobasilar and carotid arteries,and that impaired blood flow in these vessels may affect peripheral vestibular and central function.In patients with apogeotropic DCPN,examinations of vestibular function,central nervous system symptoms,and brain hemodynamics are valuable for differential diagnosis.
文摘Objective:To explore the value of four-dimensional spatiotemporal image correlation and tomographic ultrasound imaging in screening fetal congenital heart disease.Methods: A total of 671 pregnant women at 22-24 gestational weeks from January 2018 to December 2018 were examined by two-dimensional ultrasound and four-dimensional spatiotemporal image correlation and tomographic ultrasound imaging to observe the development of fetal cardiovascular structure and to compare the two methods in terms of diagnostic accuracy, examination time, image quality and new physician training cycle.Results: Cardiac malformations were found in 12 of the 671 fetuses, among which 11 cases were detected by four-dimensional spatiotemporal image correlation and tomographic ultrasound imaging and 1 case was missed. Postnatal echocardiographic reexamination and autopsy confirmed 12 cases of children with cardiac malformation, including 1 case of atrial septal defect (missed diagnosis by four-dimensional spatiotemporal image correlation and tomographic ultrasound imaging), 4 cases of tetralogy of Fallot's disease, 1 case of right ventricular double outlet, 3 cases of left ventricular dysplasia, 2 cases of complete transposition of the great artery and 1 case of tricuspid valve descending malformation. There was no statistically significant difference between four-dimensional spatiotemporal image correlation and tomographic ultrasound imaging and conventional two-dimensional color echocardiography or/and autopsy (P>0.05). In terms of examination time and new physician training, the four-dimensional spatiotemporal image correlation and tomographic ultrasound imaging technique was superior to conventional color ultrasound screening. No statistically significant difference in image quality.Conclusions:The four-dimensional spatiotemporal image correlation and tomographic ultrasound imaging can rapidly and accurately display fetal heart development, and can be used as the main screening method for fetal congenital heart disease in clinical practice.
文摘Objective:To research the effect of four-dimensional therapy on the clinical effect (symptoms, blood pressure, and pain degree), the changes of blood rheology and arterial (left vertebral artery (LVA), right vertebral artery (RVA), and basal artery (BA)) hemodynamics (average cerebral blood flow (Vm), resistance index (RI), pulsatility index (PI)) on patients with cervical hypertension. Method: Selecting 120 patients (Department of Orthopaedics, the second Affiliated Hospital to Liaoning University of Chinese Medicine, 2012.6-2018.10) with cervical hypertension, then they were divided into observation group (n=60) and control group (n=60). The control group were given enalapril meleate (amlodipine besylate) +conventional therapy (acupuncture treatment and massage), the observation group were given four-dimensional therapy on the basic of control group, they were treated 3 weeks. The primary endpoints were the changes from baseline to week 3 in the symptoms and function were scored using the Evaluation Scale for Cervical Vertigo, the secondary endpoints were changes from baseline to month 3 in the artery hemodynamics (Vm, RI, and PI) in the BA, LVA, blood rheology, and RVA. At last, assessing the pain degree through visual analog scale (VAS), measuring the blood pressure, and accessing the clinical effect.Results:The score of vertigo in the two groups had no statistical significance before treatment, the score of vertigo in the two groups were higher than pretherapy, and had statistical significance, and the score in the observation group were higher than control group, and had statistical significance. The hemodynamics (Vm, RI, and PI) in the artery (BA, LVA, and RVA) had no statistical significance in the two groups before treatment, and the hemodynamics (Vm) in the artery (BA, LVA, and RVA) were higher than pretherapy, and had statistical significance, the hemodynamics (Vm) in the artery (BA, LVA, and RVA) of observation group were higher than control group, and had statistical significance. The hemodynamics (RI and PI) in the artery (BA, LVA, and RVA) were lower than pretherapy, and had statistical significance, the the hemodynamics (Vm) in the artery (BA, LVA, and RVA) of observation group were lower than control group, and had statistical significance. The blood rheology had no statistical significance in the two groups before treatment, the blood rheology were lower than pretherapy, and had statistical significance, the blood rheology of observation group were lower than control group, and had statistical significance. The degree of VAS had no statistical significance in the two groups before treatment, the degree of VAS was lower than pretherapy, and had statistical significance, the degree of VAS of observation group were lower than control group, and had statistical significance. The blood pressure (systolic pressure and diastolic pressure) had no statistical significance in the two groups before treatment, the blood pressure (systolic pressure and diastolic pressure) were lower than pretherapy, and had statistical significance, the blood pressure (systolic pressure and diastolic pressure) of observation group were lower than control group, and had statistical significance, the clinical effect in the observation group were higher than control group, and had statistical significance.Conclusions:Giving four-dimensional therapy can improve the blood pressure and relieve the pain through improving blood rheology and hemodynamics in the artery in the patients with cervical hypertension.
文摘In this manuscript, Local dynamic behaviors including stability and Hopf bifurcation of a new four-dimensional quadratic autonomous system are studied both analytically and numerically. Determining conditions of equilibrium points on different parameters are derived. Next, the stability conditions are investigated by using Routh-Hurwitz criterion and bifurcation conditions are investigated by using Hopf bifurcation theory, respectively. It is found that Hopf bifurcation on the initial point is supercritical in this four-dimensional autonomous system. The theoretical results are verified by numerical simulation. Besides, the new four-dimensional autonomous system under the parametric conditions of hyperchaos is studied in detail. It is also found that the system can enter hyperchaos, first through Hopf bifurcation and then through periodic bifurcation.
基金The National Key Research and Development Program of China under contract Nos 2017YFC1501803 and2018YFC1506903the National Natural Science Foundation of China under contract Nos 91730304,41475021 and 41575026
文摘The four-dimensional variational assimilation(4D-Var)has been widely used in meteorological and oceanographic data assimilation.This method is usually implemented in the model space,known as primal approach(P4D-Var).Alternatively,physical space analysis system(4D-PSAS)is proposed to reduce the computation cost,in which the 4D-Var problem is solved in physical space(i.e.,observation space).In this study,the conjugate gradient(CG)algorithm,implemented in the 4D-PSAS system is evaluated and it is found that the non-monotonic change of the gradient norm of 4D-PSAS cost function causes artificial oscillations of cost function in the iteration process.The reason of non-monotonic variation of gradient norm in 4D-PSAS is then analyzed.In order to overcome the non-monotonic variation of gradient norm,a new algorithm,Minimum Residual(MINRES)algorithm,is implemented in the process of assimilation iteration in this study.Our experimental results show that the improved 4D-PSAS with the MINRES algorithm guarantees the monotonic reduction of gradient norm of cost function,greatly improves the convergence properties of 4D-PSAS as well,and significantly restrains the numerical noises associated with the traditional 4D-PSAS system.
文摘The present letter to the editor is related to the work entitled“Large leiomyoma of lower esophagus diagnosed by endoscopic ultrasonography-fine needle aspiration:A case report.”Although endoscopic ultrasonography seems necessary in a suspected leiomyoma of the esophagus,the performance of biopsies via fine needle aspiration is controversial as it increases the risk of complications such as bleeding,infection,and intraoperative perforations.Laparoscopy is the best treatment strategy for small tumors.Laparotomy with tumor enucleation or esophageal resection can be considered in large leiomyomas.
文摘BACKGROUND Omental infarction(OI)is a surgical abdominal disease that is not common in adults and is very rare in children.Similar to various acute abdominal pain diseases including appendicitis,diagnosis was previously achieved by diagnostic laparotomy but more recently,ultrasonography or computed tomography(CT)examination has been used.CASE SUMMARY A 6-year-old healthy boy with no specific medical history visited the emergency room with right lower abdominal pain.He underwent abdominal ultrasonography by a radiologist to rule out acute appendicitis.He was discharged with no significant sonographic finding and symptom relief.However,the symptoms persisted for 2 more days and an outpatient visit was made.An outpatient abdominal CT was used to make a diagnosis of OI.After laparoscopic operation,his symptoms resolved.CONCLUSION In children’s acute abdominal pain,imaging studies should be performed for appendicitis and OI.
