Variability in the location and shape of the dayside magnetopause is attributed to magnetic reconnection,a fundamental process that enables the transfer of mass,energy,and momentum from the solar wind into the magneto...Variability in the location and shape of the dayside magnetopause is attributed to magnetic reconnection,a fundamental process that enables the transfer of mass,energy,and momentum from the solar wind into the magnetosphere.The spatial and temporal properties of the magnetopause,under varying solar and magnetospheric conditions,remain largely unknown because empirical studies using in-situ observations are challenging to interpret.Global wide field-of-view(FOV)imaging is the only means to simultaneously observe the spatial distribution of the plasma properties over the vast dayside magnetospheric region and,subsequently,quantify the energy transport from the interplanetary medium into the terrestrial magnetosphere.Two upcoming missions,ESA/CAS SMILE and NASA’s LEXI will provide wide-field imagery of the dayside magnetosheath in soft X-rays,an emission generated by charge exchange interactions between high charge-state heavy ions of solar wind origin and exospheric neutral atoms.High-cadence two-dimensional observations of the magnetosheath will allow the estimation of dynamic properties of its inner boundary,the magnetopause,and enable studies of its response to changes in the solar wind dynamic pressure and interplanetary magnetic field orientation.This work introduces a statistically-based estimation approach based on inverse theory to estimate the spatial distribution of magnetosheath soft X-ray emissivities and,with this,identify the location of the magnetopause over the Sun−Earth line.To do so,we simulate the magnetosheath structure using the MHD-based OpenGGCM model and generate synthetic soft X-ray images using LEXI’s orbit and attitude information.Our results show that 3-D estimations using the described statistically-based technique are robust against Poisson-distributed shot noise inherent to soft X-ray images.Also,our proposed methodology shows that the accuracy of both three-dimensional(3-D)estimation and the magnetopause standoff distance calculation highly depends on the observational point.展开更多
This paper presents a system approach of mass balance calculations of ozone and other species under diffusion-convection-reaction processes to study the impacts of major ozone-depleting chemicals, chlorine (Cl) and ch...This paper presents a system approach of mass balance calculations of ozone and other species under diffusion-convection-reaction processes to study the impacts of major ozone-depleting chemicals, chlorine (Cl) and chlorine monoxide (ClO), and the effect of photolysis on ozone concentrations, ozone depletion, total ozone abundance, and ozone layer along the altitude in the stratosphere. The calculated ozone concentrations and profile of the layer followed a similar trend and were generally in good agreement with the measurements above the tropical area. The calculated peak of the layer was at the same mid-stratosphere at Z = 30 km with a peak concentration and total ozone abundance about 20% higher than the measured peak concentration of 8.0 ppm and total abundance of 399 DU. In the presence of Cl and ClO, the calculated ozone concentrations and total abundance were substantially reduced. Cl generally depleted more uniformly of ozone across the altitude, while ClO reduced substantially the ozone in the upper stratosphere and thus shifted the peak of the layer to a much lower elevation at Z = 14 km. Although both ClO and Cl are active ozone-depleting chemicals, ClO was found to have a more pronounced impact on ozone depletion and distribution than Cl. The possible explanations of these interesting phenomena were discussed and elaborated. The approach and calculations in this paper were shown to be useful in providing an initial insight into the structure and behavior of the complex ozone layer.展开更多
The Lunar Environment heliospheric X-ray Imager(LEXI)and Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)missions will image the Earth’s dayside magneto pause and cusps in soft X-rays after their respective l...The Lunar Environment heliospheric X-ray Imager(LEXI)and Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)missions will image the Earth’s dayside magneto pause and cusps in soft X-rays after their respective launches in the near future,to specify glo bal magnetic reconnection modes for varying solar wind conditions.To suppo rt the success of these scientific missions,it is critical to develop techniques that extract the magnetopause locations from the observed soft X-ray images.In this research,we introduce a new geometric equation that calculates the subsolar magnetopause position(RS)from a satellite position,the look direction of the instrument,and the angle at which the X-ray emission is maximized.Two assumptions are used in this method:(1)The look direction where soft X-ray emissions are maximized lies tangent to the magnetopause,and(2)the magnetopause surface near the subsolar point is almost spherical and thus RSis nea rly equal to the radius of the magneto pause curvature.We create synthetic soft X-ray images by using the Open Geospace General Circulation Model(OpenGGCM)global magnetohydrodynamic model,the galactic background,the instrument point spread function,and Poisson noise.We then apply the fast Fourier transform and Gaussian low-pass filte rs to the synthetic images to re move noise and obtain accurate look angles for the soft X-ray pea ks.From the filte red images,we calculate RS and its accuracy for different LEXI locations,look directions,and solar wind densities by using the OpenGGCM subsolar magnetopause location as ground truth.Our method estimates RS with an accuracy of<0.3 RE when the solar wind density exceeds>10 cm-3.The accuracy improves for greater solar wind densities and during southward interplanetary magnetic fields.The method ca ptures the magnetopause motion during southwa rd interplaneta ry magnetic field turnings.Consequently,the technique will enable quantitative analysis of the magnetopause motion and help reveal the dayside reconnection modes for dynamic solar wind conditions.This technique will suppo rt the LEXI and SMILE missions in achieving their scientific o bjectives.展开更多
A dynamic reconfiguration method for photovoltaic(PV)arrays based on an improved dung beetle algorithm(IDBO)to address the issue of PV array mismatch loss caused by partial shading conditions(PSCs)is proposed.To estab...A dynamic reconfiguration method for photovoltaic(PV)arrays based on an improved dung beetle algorithm(IDBO)to address the issue of PV array mismatch loss caused by partial shading conditions(PSCs)is proposed.To establish the output power-current(P-I)segmentation function for the total-cross-tied(TCT)PV array and the constraint function for the electrical switches,the IDBO algorithm was used to optimize both the P-I segmentation function and the electrical switch constraint function.IDBO is compared with algorithm-free reconfiguration and five other heuristic algorithms using two evaluation criteria:mismatch loss and power enhancement percentage,across six shading scenarios for 6x6 PV arrays.The irradiation distribution of PV arrays reconfigured by IDBO is also presented.The results show that IDBO effectively increases the output power of PV arrays and reduces mismatch loss.The output PV curves tend to exhibit a single peak,and the reconstruction results are superior to those obtained with the other methods.展开更多
BACKGROUND:Traumatic cardiac arrest(TCA)is a major contributor to mortality and morbidity in all age groups and poses a significant burden on the healthcare system.Although there have been advances in treatment modali...BACKGROUND:Traumatic cardiac arrest(TCA)is a major contributor to mortality and morbidity in all age groups and poses a significant burden on the healthcare system.Although there have been advances in treatment modalities,survival rates for TCA patients remain low.This narrative literature review critically examines the indications and eff ectiveness of current therapeutic approaches in treating TCA.METHODS:We performed a literature search in the PubMed and Scopus databases for studies published before December 31,2022.The search was refi ned by combining search terms,examining relevant study references,and restricting publications to the English language.Following the search,943 articles were retrieved,and two independent reviewers conducted a screening process.RESULTS:A review of various studies on pre-and intra-arrest prognostic factors showed that survival rates were higher when patients had an initial shockable rhythm.There were conflicting results regarding other prognostic factors,such as witnessed arrest,bystander cardiopulmonary resuscitation(CPR),and the use of prehospital or in-hospital epinephrine.Emergency thoracotomy was found to result in more favorable outcomes in cases of penetrating trauma than in those with blunt trauma.Resuscitative endovascular balloon occlusion of the aorta(REBOA)provides an advantage to emergency thoracotomy in terms of occupational safety for the operator as an alternative in managing hemorrhagic shock.When implemented in the setting of aortic occlusion,emergency thoracotomy and REBOA resulted in comparable mortality rates.Veno-venous extracorporeal life support(V-V ECLS)and veno-arterial extracorporeal life support(V-A ECLS)are viable options for treating respiratory failure and cardiogenic shock,respectively.In the context of traumatic injuries,V-V ECLS has been associated with higher rates of survival to discharge than V-A ECLS.CONCLUSION:TCA remains a signifi cant challenge for emergency medical services due to its high morbidity and mortality rates.Pre-and intra-arrest prognostic factors can help identify patients who are likely to benefit from aggressive and resource-intensive resuscitation measures.Further research is needed to enhance guidelines for the clinical use of established and emerging therapeutic approaches that can help optimize treatment effi cacy and ameliorate survival outcomes.展开更多
Resistance to pentavalent antimonial drugs and the lack of vaccines make it urgent to find novel therapeutic options to treat Leishmaniasis, a tropical disease caused by the Leishmania protozoan parasite. The study re...Resistance to pentavalent antimonial drugs and the lack of vaccines make it urgent to find novel therapeutic options to treat Leishmaniasis, a tropical disease caused by the Leishmania protozoan parasite. The study reported here is to investigate if Streptomycin, an aminoglycoside, and Amphotericin B, the second-line treatment drug, exhibit antileishmanial activity through a similar mechanism. By using MOE (Molecular Operating Environment), we performed molecular docking studies on these drugs binding to a range of targets including ribosome targets in Leishmania and H. sapiens. Our study shows that the two drugs do not bind to the same pockets in Leishmania targets but to the same pockets in the human ribosome, with some differences in interactions. Moreover, our 2D maps indicated that Amphotericin B binds to the A-site in the human cytoplasmic ribosome, whereas streptomycin does not.展开更多
This paper presents an engineering system approach using a 2D model of conservation of mass to study the dynamics of ozone and concerned chemical species in the stratosphere.By considering all fourteen photolysis,ozon...This paper presents an engineering system approach using a 2D model of conservation of mass to study the dynamics of ozone and concerned chemical species in the stratosphere.By considering all fourteen photolysis,ozone-generating,and-depleting chemical reactions,the model calculated the transient,spatial changes of ozone under different physical-chemical-radiative conditions.Validation against the measured data demonstrated good accuracy,close match of our model with the observed ozone concentrations at both 20°S and 90°N locations.The deviation in the average concentration was less than 1% and in ozone profiles less than 17%.The impacts of various chlorine-(Cl),nitrogen oxides-(NO_(x)),and bromine-(Br)depleting cycles on ozone concentrations and distribution were investigated.The chlorine catalytic depleting cycle was found to exhibit the most significant impact on ozone dynamics,confirming the key role of chlorine in the problem of ozone depletion.Sensitivity analysis was conducted with levels of 25%,50%,100%,200%,and 400% of the baseline value.The combined cycles(Cl+NO_(x)+Br)showed the most significant influence on ozone behavior.The total ozone abundance above the South Pole could decrease by a small 3%,from 281 DU(Dubson Units)to 273 DU for the 25% level,or by a huge thinning of 60%to 114 DU for the 400% concentration level.When the level of chlorine gases increased beyond 200%,it would cause ozone depletion to a level of ozone hole(below 220 DU).The 2D Ozone Model presented in this paper demonstrates robustness,convenience,efficiency,and executability for analyzing complex ozone phenomena in the stratosphere.展开更多
Developing a predictive model for detecting cardiovascular diseases (CVDs) is crucial due to its high global fatality rate. With the advancements in artificial intelligence, the availability of large-scale data, and i...Developing a predictive model for detecting cardiovascular diseases (CVDs) is crucial due to its high global fatality rate. With the advancements in artificial intelligence, the availability of large-scale data, and increased access to computational capability, it is feasible to create robust models that can detect CVDs with high precision. This study aims to provide a promising method for early diagnosis by employing various machine learning and deep learning techniques, including logistic regression, decision trees, random forest classifier, extreme gradient boosting (XGBoost), and a sequential model from Keras. Our evaluation identifies the random forest classifier as the most effective model, achieving an accuracy of 0.91, surpassing other machine learning and deep learning approaches. Close behind are XGBoost (accuracy: 0.90), decision tree (accuracy: 0.86), and logistic regression (accuracy: 0.70). Additionally, our deep learning sequential model demonstrates promising classification performance, with an accuracy of 0.80 and a loss of 0.425 on the validation set. These findings underscore the potential of machine learning and deep learning methodologies in advancing cardiovascular disease prediction and management strategies.展开更多
基金supported by NASA Goddard Space Flight Center through Cooperative Agreement 80NSSC21M0180 to Catholic UniversityPartnership for Heliophysics and Space Environment Research(PHaSER)+2 种基金the NASA Heliophysics United States Participating Investigator Program under Grant WBS516741.01.24.01.03(DS)support from the NASA grants 80NSSC19K0844,80NSSC20K1670,and 80MSFC20C0019the NASA GSFC internal fundings(HIF,ISFM,and IRAD)。
文摘Variability in the location and shape of the dayside magnetopause is attributed to magnetic reconnection,a fundamental process that enables the transfer of mass,energy,and momentum from the solar wind into the magnetosphere.The spatial and temporal properties of the magnetopause,under varying solar and magnetospheric conditions,remain largely unknown because empirical studies using in-situ observations are challenging to interpret.Global wide field-of-view(FOV)imaging is the only means to simultaneously observe the spatial distribution of the plasma properties over the vast dayside magnetospheric region and,subsequently,quantify the energy transport from the interplanetary medium into the terrestrial magnetosphere.Two upcoming missions,ESA/CAS SMILE and NASA’s LEXI will provide wide-field imagery of the dayside magnetosheath in soft X-rays,an emission generated by charge exchange interactions between high charge-state heavy ions of solar wind origin and exospheric neutral atoms.High-cadence two-dimensional observations of the magnetosheath will allow the estimation of dynamic properties of its inner boundary,the magnetopause,and enable studies of its response to changes in the solar wind dynamic pressure and interplanetary magnetic field orientation.This work introduces a statistically-based estimation approach based on inverse theory to estimate the spatial distribution of magnetosheath soft X-ray emissivities and,with this,identify the location of the magnetopause over the Sun−Earth line.To do so,we simulate the magnetosheath structure using the MHD-based OpenGGCM model and generate synthetic soft X-ray images using LEXI’s orbit and attitude information.Our results show that 3-D estimations using the described statistically-based technique are robust against Poisson-distributed shot noise inherent to soft X-ray images.Also,our proposed methodology shows that the accuracy of both three-dimensional(3-D)estimation and the magnetopause standoff distance calculation highly depends on the observational point.
文摘This paper presents a system approach of mass balance calculations of ozone and other species under diffusion-convection-reaction processes to study the impacts of major ozone-depleting chemicals, chlorine (Cl) and chlorine monoxide (ClO), and the effect of photolysis on ozone concentrations, ozone depletion, total ozone abundance, and ozone layer along the altitude in the stratosphere. The calculated ozone concentrations and profile of the layer followed a similar trend and were generally in good agreement with the measurements above the tropical area. The calculated peak of the layer was at the same mid-stratosphere at Z = 30 km with a peak concentration and total ozone abundance about 20% higher than the measured peak concentration of 8.0 ppm and total abundance of 399 DU. In the presence of Cl and ClO, the calculated ozone concentrations and total abundance were substantially reduced. Cl generally depleted more uniformly of ozone across the altitude, while ClO reduced substantially the ozone in the upper stratosphere and thus shifted the peak of the layer to a much lower elevation at Z = 14 km. Although both ClO and Cl are active ozone-depleting chemicals, ClO was found to have a more pronounced impact on ozone depletion and distribution than Cl. The possible explanations of these interesting phenomena were discussed and elaborated. The approach and calculations in this paper were shown to be useful in providing an initial insight into the structure and behavior of the complex ozone layer.
基金supported by NASA(Grant Nos.80NSSC19K0844,80NSSC20K1670,80MSFC20C0019,and 80GSFC21M0002)support from NASA Goddard Space Flight Center internal funding programs(HIF,Internal Scientist Funding Model,and Internal Research and Development)。
文摘The Lunar Environment heliospheric X-ray Imager(LEXI)and Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)missions will image the Earth’s dayside magneto pause and cusps in soft X-rays after their respective launches in the near future,to specify glo bal magnetic reconnection modes for varying solar wind conditions.To suppo rt the success of these scientific missions,it is critical to develop techniques that extract the magnetopause locations from the observed soft X-ray images.In this research,we introduce a new geometric equation that calculates the subsolar magnetopause position(RS)from a satellite position,the look direction of the instrument,and the angle at which the X-ray emission is maximized.Two assumptions are used in this method:(1)The look direction where soft X-ray emissions are maximized lies tangent to the magnetopause,and(2)the magnetopause surface near the subsolar point is almost spherical and thus RSis nea rly equal to the radius of the magneto pause curvature.We create synthetic soft X-ray images by using the Open Geospace General Circulation Model(OpenGGCM)global magnetohydrodynamic model,the galactic background,the instrument point spread function,and Poisson noise.We then apply the fast Fourier transform and Gaussian low-pass filte rs to the synthetic images to re move noise and obtain accurate look angles for the soft X-ray pea ks.From the filte red images,we calculate RS and its accuracy for different LEXI locations,look directions,and solar wind densities by using the OpenGGCM subsolar magnetopause location as ground truth.Our method estimates RS with an accuracy of<0.3 RE when the solar wind density exceeds>10 cm-3.The accuracy improves for greater solar wind densities and during southward interplanetary magnetic fields.The method ca ptures the magnetopause motion during southwa rd interplaneta ry magnetic field turnings.Consequently,the technique will enable quantitative analysis of the magnetopause motion and help reveal the dayside reconnection modes for dynamic solar wind conditions.This technique will suppo rt the LEXI and SMILE missions in achieving their scientific o bjectives.
基金Supported by the National Natural Science Foundation of China(61903291)the Key R&D Project in Shaanxi Province(2022GY-134)+1 种基金the Open Fund Project of New Energy Joint Laboratory of China Southern Power Grid Corporation in 2022(GDXNY2022KF01)the China Southern Power Grid Laboratory Open Subject Fund Project(0304002022030103GD00037).
文摘A dynamic reconfiguration method for photovoltaic(PV)arrays based on an improved dung beetle algorithm(IDBO)to address the issue of PV array mismatch loss caused by partial shading conditions(PSCs)is proposed.To establish the output power-current(P-I)segmentation function for the total-cross-tied(TCT)PV array and the constraint function for the electrical switches,the IDBO algorithm was used to optimize both the P-I segmentation function and the electrical switch constraint function.IDBO is compared with algorithm-free reconfiguration and five other heuristic algorithms using two evaluation criteria:mismatch loss and power enhancement percentage,across six shading scenarios for 6x6 PV arrays.The irradiation distribution of PV arrays reconfigured by IDBO is also presented.The results show that IDBO effectively increases the output power of PV arrays and reduces mismatch loss.The output PV curves tend to exhibit a single peak,and the reconstruction results are superior to those obtained with the other methods.
文摘BACKGROUND:Traumatic cardiac arrest(TCA)is a major contributor to mortality and morbidity in all age groups and poses a significant burden on the healthcare system.Although there have been advances in treatment modalities,survival rates for TCA patients remain low.This narrative literature review critically examines the indications and eff ectiveness of current therapeutic approaches in treating TCA.METHODS:We performed a literature search in the PubMed and Scopus databases for studies published before December 31,2022.The search was refi ned by combining search terms,examining relevant study references,and restricting publications to the English language.Following the search,943 articles were retrieved,and two independent reviewers conducted a screening process.RESULTS:A review of various studies on pre-and intra-arrest prognostic factors showed that survival rates were higher when patients had an initial shockable rhythm.There were conflicting results regarding other prognostic factors,such as witnessed arrest,bystander cardiopulmonary resuscitation(CPR),and the use of prehospital or in-hospital epinephrine.Emergency thoracotomy was found to result in more favorable outcomes in cases of penetrating trauma than in those with blunt trauma.Resuscitative endovascular balloon occlusion of the aorta(REBOA)provides an advantage to emergency thoracotomy in terms of occupational safety for the operator as an alternative in managing hemorrhagic shock.When implemented in the setting of aortic occlusion,emergency thoracotomy and REBOA resulted in comparable mortality rates.Veno-venous extracorporeal life support(V-V ECLS)and veno-arterial extracorporeal life support(V-A ECLS)are viable options for treating respiratory failure and cardiogenic shock,respectively.In the context of traumatic injuries,V-V ECLS has been associated with higher rates of survival to discharge than V-A ECLS.CONCLUSION:TCA remains a signifi cant challenge for emergency medical services due to its high morbidity and mortality rates.Pre-and intra-arrest prognostic factors can help identify patients who are likely to benefit from aggressive and resource-intensive resuscitation measures.Further research is needed to enhance guidelines for the clinical use of established and emerging therapeutic approaches that can help optimize treatment effi cacy and ameliorate survival outcomes.
文摘Resistance to pentavalent antimonial drugs and the lack of vaccines make it urgent to find novel therapeutic options to treat Leishmaniasis, a tropical disease caused by the Leishmania protozoan parasite. The study reported here is to investigate if Streptomycin, an aminoglycoside, and Amphotericin B, the second-line treatment drug, exhibit antileishmanial activity through a similar mechanism. By using MOE (Molecular Operating Environment), we performed molecular docking studies on these drugs binding to a range of targets including ribosome targets in Leishmania and H. sapiens. Our study shows that the two drugs do not bind to the same pockets in Leishmania targets but to the same pockets in the human ribosome, with some differences in interactions. Moreover, our 2D maps indicated that Amphotericin B binds to the A-site in the human cytoplasmic ribosome, whereas streptomycin does not.
文摘This paper presents an engineering system approach using a 2D model of conservation of mass to study the dynamics of ozone and concerned chemical species in the stratosphere.By considering all fourteen photolysis,ozone-generating,and-depleting chemical reactions,the model calculated the transient,spatial changes of ozone under different physical-chemical-radiative conditions.Validation against the measured data demonstrated good accuracy,close match of our model with the observed ozone concentrations at both 20°S and 90°N locations.The deviation in the average concentration was less than 1% and in ozone profiles less than 17%.The impacts of various chlorine-(Cl),nitrogen oxides-(NO_(x)),and bromine-(Br)depleting cycles on ozone concentrations and distribution were investigated.The chlorine catalytic depleting cycle was found to exhibit the most significant impact on ozone dynamics,confirming the key role of chlorine in the problem of ozone depletion.Sensitivity analysis was conducted with levels of 25%,50%,100%,200%,and 400% of the baseline value.The combined cycles(Cl+NO_(x)+Br)showed the most significant influence on ozone behavior.The total ozone abundance above the South Pole could decrease by a small 3%,from 281 DU(Dubson Units)to 273 DU for the 25% level,or by a huge thinning of 60%to 114 DU for the 400% concentration level.When the level of chlorine gases increased beyond 200%,it would cause ozone depletion to a level of ozone hole(below 220 DU).The 2D Ozone Model presented in this paper demonstrates robustness,convenience,efficiency,and executability for analyzing complex ozone phenomena in the stratosphere.
文摘Developing a predictive model for detecting cardiovascular diseases (CVDs) is crucial due to its high global fatality rate. With the advancements in artificial intelligence, the availability of large-scale data, and increased access to computational capability, it is feasible to create robust models that can detect CVDs with high precision. This study aims to provide a promising method for early diagnosis by employing various machine learning and deep learning techniques, including logistic regression, decision trees, random forest classifier, extreme gradient boosting (XGBoost), and a sequential model from Keras. Our evaluation identifies the random forest classifier as the most effective model, achieving an accuracy of 0.91, surpassing other machine learning and deep learning approaches. Close behind are XGBoost (accuracy: 0.90), decision tree (accuracy: 0.86), and logistic regression (accuracy: 0.70). Additionally, our deep learning sequential model demonstrates promising classification performance, with an accuracy of 0.80 and a loss of 0.425 on the validation set. These findings underscore the potential of machine learning and deep learning methodologies in advancing cardiovascular disease prediction and management strategies.
