检索结果-南通市图书馆

Early Phases of Star Formation: Testing chemical Tools

Research in Astronomy and Astrophysics 2024年第1期24卷 96-118页

作者： N.c.martinez S.Paron cONIcET-Universidad de Buenos Aires.Instituto de Astronomía y Física del Espacio Ciudad Universitaria(C1428EGA)Ciudad Autónoma de Buenos AiresArgentina

Star-forming processes strongly influence the ISm ***,many high-quality databases are available at millimeter *** them,it is possible to carry out studies that review and deepen previous *** these studies involve large samples of sources,it is preferred to use direct tools to study the molecular *** the aim of testing these tools such as the use of the HcN/HNc ratio as a thermometer,and the use of H^(13)cO^(+),Hc_(3)N,N_(2)H^(+) and c_(2)H as "chemical clocks," we present a molecular line study toward 55 sources representing massive young stellar objects at different evolutionary stages:infrared dark clouds(IRDcs),highmass protostellar objects(HmPOs),hot molecular cores(Hmcs) and ultracompact H II *** found that the use of the HcN/HNc ratio as a universal thermometer in the ISm should be taken with care because the HcN optical depth is a big issue that can affect the ***,this tool should be utilized only after a careful analysis of the HcN spectrum,checking that no line,neither the main nor the hyperfine ones,presents absorption *** point out that the analysis of the emission of H^(13)cO^(+),Hc_(3)N,N_(2)H^(+) and c_(2)H could be useful to trace and distinguish regions among IRDcs,HmPOs and *** molecular line widths of these four species increase from the IRDc to the Hmc stage,which can be a consequence of the gas dynamics related to the starforming processes taking place in the molecular *** results not only contribute with more statistics,acting as a probe of such chemical tools,useful to obtain information in large samples of sources,but also complement previous works through the analysis of other types of sources.

关键词： stars:formation ISm:molecules ISm:clouds

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

circulation Pattern controls of Summer Temperature Anomalies in Southern Africa

引用

Advances in Atmospheric Sciences 2024年第2期41卷 341-354页

作者： chibuike chiedozie IBEBUcHI cameron c.LEE Department of Geography Kent State UniversityKentOhio 44242USA climRISE Lab Kent State UniversityKentOhio 44242USA

This study investigates the relationship between circulation patterns and austral summer temperature anomalies in southern Africa. The results show that the formation of continental lows tends to increase the thickness of the lower atmosphere. Further, the distinct variabilities of high and low pressure under the circulation types, influence air mass advection from the adjacent oceans, as well as atmospheric stability over land. Stronger anticyclonic circulation at the western branch of the mascarene high-pressure system enhances the low-level cold air advection by southeast winds,decreases the thickness, and lowers the temperature over a majority of the land in southern Africa. conversely, a weaker mascarene High, coupled with enhanced cyclonic activity in the southwest Indian Ocean increases low-level warm air advection and increases temperature anomalies over vast regions in southern Africa. The ridging of a closed South Atlantic anticyclone at the southern coast of southern Africa results in colder temperatures near the tip of southern Africa due to enhanced low-level cold air advection by southeast winds. However, when the ridge is weak and westerly winds dominate the southern coast of southern Africa, these areas experience temperature increases. The northward track of the Southern Hemisphere mid-latitude cyclone, which can be linked to the negative Southern Annular mode, reduces the temperature in the southwestern part of southern Africa. Also, during the analysis period, El Ni?o was associated with temperature increases over the central parts of southern Africa;while the positive Indian Ocean dipole was linked to a temperature increase over the northeastern, northwestern, and southwestern parts of southern Africa.

关键词： temperature circulation types Subtropical Indian Ocean dipole Southern Annular mode El Ni?o Indian Ocean dipole mascarene High South Atlantic anticyclone

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Imprints of a gravitational wave through the weak field deflection of photons

引用

chinese Physics c 2024年第8期48卷 240-245页

作者： Reggie c.Pantig Ali Övgün Physics Department Mapúa University658 Muralla St.IntramurosManila 1002Philippines Physics Department Eastern Mediterranean UniversityFamagusta99628 North Cyprusvia Mersin 10Turkiye

In this study,we investigate the novel phenomenon of gravitational lensing experienced by gravitational waves traveling past a Schwarzschild black hole perturbed by a specific,first-order,polar gravitational *** apply the Gauss-Bonnet theorem,finding a topological contribution to the deflection of light rays passing near the black *** demonstrate that the deflection angle can be determined by analyzing a region entirely outside the path of the light ray,leading to a calculation based solely on the parameters of the perturbing wave(Legendre polynomial order,l;frequency,σ).This approach offers a unique perspective on gravitational lensing and expands our understanding of black hole interactions with gravitational waves.

关键词： supermassive black holes gravitational waves chaos weak deflection angle Gauss-Bonnet theorem

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Facile synthesis of samarium and cerium doped double perovskite cobaltite with enhanced dielectric response

引用

Journal of Rare Earths 2024年第7期42卷 1317-1327,I0005页

作者： Yasir Abbas m.Kamran m.Anis-ur-Rehman Applied Thermal Physics Laboratory Department of PhysicsCOMSATS University IslamabadIslamabad 45550Pakistan

The investigation of Sm-ce doping on structure,conduction,and dielectric response of Bi_(2)ca_(2-2x)Sm_(x)cexcoO_(6)(x=0.000,0.025,0.050,0.075)(BcSccO)are *** the specimens were synthesized by a facile synthesis technique named the co-precipitation route.X-ray diffraction(XRD)reveals that BcSccO crystallizes into one phase with space group P21/*** crystallite size,dislocation density,lattice parameters,lattice strain,unit cell volume,and bulk density were determined using XRD *** structural properties of Bi_(2)ca_(2)coO_(6)were examined using calculations based on the density functional *** and experimental values discrepancy is less than 1%.A scanning electron microscope was used for performing a microstructural *** SEm images demonstrate the homogeneous distribution of grains with a range of sizes(0.054-0.090μm).The alternating current(ac)conductivity,dielectric permittivity,and tangent loss were also studied as a function of frequency(20 Hz-3 mHz)at different temperatures(100-500℃).All synthesized samples were examined using non-linear Debye's function to determine their spreading factor and relaxation *** specimen with the lowest crystallite size(∼23 nm)exhibits a high dielectric permittivity(∼3.80×10^(6)).The conduction mechanism was examined in the studied samples with the use of Jonscher's power *** power law indicates that the BcSccO(x=0.000,0.025)follows correlated barrier hopping,whereas the x=0.050 and 0.075 compositions follow non-overlapping polaron *** studied specimen Bi_(2)ca_(1.9)0Sm_(0.05)0ce_(0.05)_(0)coO_(6)with the highest density(∼5.65 g/cm^(3))displays a high electrical conductivity(∼46.1 S/cm).These findings correspond to those published for ceramics made from calcium cobaltite using solid-state reactions(5.0-26.0 S/cm).

关键词： Bismuth calcium samarium cerium cobaltite (BcSccO) Spreading factor conduction mechanism Rare earths

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Enhanced saturation magnetization in La^(3+) doped Nico ferrites prepared by sol-gel auto-combustion method

引用

Journal of Rare Earths 2024年第8期42卷 1546-1554,I0005页

作者： maddileti Jelli Vidyasagar Thopudurthy Krishna Reddy c.V. Department of Physics Rayalaseema UniversityKurnoolA.P518007.Iindia Department of Physics Government PolytechnicRayachotiA.P516269India

Lanthanum doped nickel-cobalt nano ferrites with chemical formula Ni_(0.5)co_(0.5)LaxFe_(2-x)O_(4)(x=0.05,0,10,0.15 and 0,20) were prepared using a simple sol-gel auto combustion *** basic structural properties were determined by X-ray diffraction method and the formation of single phased spinel ferrite was *** crystalline size decreased from 25 to 11 nm and lattice parameter a increases with increase of La *** surface morphology of these ferrites was observed by field-emission scanning electron microscopy(FESEm) and agglomerated irregular grains are observed with increase of the rare earth element La ***-dispersive X-ray spectroscopy(EDX) result confirms the presence of the required *** Fourier transform infrared spectroscopy(FTIR) spectrum indicates the formation of the spinel ferrite structure with m-O *** direct band measurements from ultraviolet-visible spectroscopy(UV-Vis) spectroscopy indicate that the direct band gap decreases from 1.39 to 1.19 eV for x=0.05 to x=0.15,then increases to 1.28 eV for x=*** room temperature magnetic properties of these ferrites were studied by a vibrating sample magnetometer(VSm).The enhanced saturation magnetization of 49.73 emu/g is observed for x=0.10 and then saturation magnetizations are gradually decreased for x=0.15 and x=*** the remanent magnetization and coercivity also follow the same trend.

关键词： Ferrites Sol-gel auto combustion La doping magnetic properties Rare earths

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

The value of the INFEcTIONS scoring system in identifying bacterial infections among patients presenting at the emergency department of a middle-income country:A pilot study

引用

chinese Journal of Traumatology 2024年第2期27卷 77-82页

作者： Dooshanveer c.Nuckchady Department of Internal medicine Victoria HospitalCandosMauritius

Purpose:To investigate which scoring system is the most accurate tool in predicting mortality among the infected patients who present to the emergency department in a middle-income country,and to validate a new scoring system to predict bacterial ***:This was a retrospective,single-center study among patients who were admitted via the emergency department of a public *** patients who were started on antibiotics were included in the study,while patients agedcollected includeding patients'demographics,vital signs and basic laboratory parameters like white blood cell count and *** sensitivity and specificity of different scoring systems were calculated as well as their negative and positive predictive *** regression was used to derive a novel early warning system for bacterial *** area under the receiver operating characteristic(AUROc)was computed for each scoring ***:In total,109 patients were included in this *** quick sequential organ failure assessment(qSOFA),search out severity and rapid acute physiology score had the highest AUROc(≥0.89)for predicting mortality,while qSOFA and universal vital assessment were the simplest scoring systems with an AUROc>0.85;however,these scoring systems failed to predict whether patients were truly *** INFEcTIONS(short for impaired mental status,not conscious,fast heart rate,elevated creatinine,high temperature,on inotrope,low oxygen,high neutrophils and high sugar)model reached an AUROc of 0.88 to more accurately predict the infectious state of a ***:middle-income countries should use the qSOFA or universal vital assessment score to identify the sickest patients in emergency *** INFEcTIONS score may help recognize patients with bacterial infections,but it should be further validated in multiple countries prior to widely use.

关键词： Prognosis mortality Bacterial infection INFEcTIONS scoring system Sequential organ failure assessment Prediction

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Braneworld black holes with modmax electrodynamics on the brane

引用

communications in Theoretical Physics 2024年第6期76卷 120-128页

作者： Haryanto m Siahaan Jurusan Fisika Universitas Katolik ParahyanganJalan Ciumbuleuit 94Bandung 40141Indonesia

In this study,we investigate modmax electrodynamics localized within the Randall-Sundrum Ⅱ and Dvali-Gabadadze-Porrati branes,deriving corresponding 3-brane spacetime solutions that conform to the effective Einstein equations in each specific *** construct solutions for charged black holes within the effective Einstein equation framework in both braneworld *** examination explores the trajectories of charged objects in this spacetime,underscoring the significance of the nonlinear *** analysis uncovers the fact that,similar to the prior modmax black hole investigation,the nonlinear parameter plays a pivotal role in suppressing the effective charge of the black hole,due to its definite positive value.

关键词： RS-II DGP modmax brane

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Higgs-like(pseudo)scalars in AdS_(4),marginal and irrelevant deformations in cFT_(3),and instantons on S^(3)

引用

chinese Physics c 2024年第4期48卷 68-81页

作者： m.Naghdi Department of Physics Faculty of Basic SciencesUniversity of IlamIlamIran

Employing a 4-form ansatz of 11-dimensional supergravity over a non-dynamical AdS_(4)×S^(7)/Z_(k)background and setting the internal space as an S1 Hopf fibration on cP3,we obtain a consistent ***(pseudo)scalars,in the resulting scalar equations in Euclidean AdS_(4)space,may be considered to arise from(anti)m-branes wrapping around the internal directions in the(Wick-rotated)skew-whiffed m2-brane background(as the resulting theory is for anti-m2-branes),thus realizing the modes after swapping the three fundamental representations 8_(s),8_(c),and 8_(v) of SO(8).Taking the backreaction on the external and internal spaces,we obtain the massless and massive modes,corresponding to exactly marginal and marginally irrelevant deformations on the boundary cFT3,***,we obtain a closed solution for the bulk equation and compute its correction with respect to the background ***,considering the Higgs-like(breathing)mode m^(2)=18,having all supersymmetries as well as parity and scale-invariance broken,solving the associated bulk equation with mathematical methods,specifically the Adomian decomposition method,and analyzing the behavior near the boundary of the solutions,we realize the boundary duals in the SU(4)×U(1)-singlet sectors of the ABJm ***,introducing the new dual deformationΔ_(+)=3,6 operators made of bi-fundamental scalars,fermions,and U(1)gauge fields,we obtain the SO(4)-invariant solutions as small instantons on a three-sphere with the radius at infinity,which correspond to collapsing bulk bubbles leading to big-crunch singularities.

关键词： AdS_(4)/cFT_(3)correspondence scalar equations in AdS_(4) instantons marginal and irrelevant operators (anti)m-branes

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Otolaryngology residency program factors associated with female resident representation

引用

World Journal of Otorhinolaryngology-Head and Neck Surgery 2024年第1期10卷 7-11页

作者： Julia E.canick James c.campbell charles R.Woodard Lars J.Grimm Alissa m.collins Duke University School of medicine DurhamNorth CarolinaUSA Department of Head and Neck Surgery&communication Sciences Duke University School of MedicineDurhamNorth CarolinaUSA Department of Radiology Duke University School of MedicineDurhamNorth CarolinaUSA

Objective:Female representation in the field of otolaryngology is *** is the first point at which medical school graduates specialize in a chosen field and thus represents an opportunity to recruit and train more female *** study sought to identify program factors associated with greater female representation among resident ***:Departmental websites of all 124 otolaryngology residency programs in the United States and Puerto Rico were examined for a list of *** programs with a resident roster available,the genders of residents,faculty,program directors,and chairpersons were *** and city population for each program was also recorded,as was female resident *** were compared using Pearson chi‐squared univariate ***:1,632 residents and 2,605 faculty were included in the analysis of 109 *** median female resident representation was 40%.Programs with larger faculty sizes,more female faculty,and urban location were associated with an above‐median female resident *** with a larger residency cohort approached significance regarding above‐median female resident *** female faculty representation,program director gender,chairperson gender,and US region were not associated with variation in female resident ***:Greater female otolaryngology residency representation was associated with programs having an urban location and greater numbers of female and total *** was also likely that a larger resident cohort size may affect female resident *** proportions of female faculty,program director,and chairperson gender,as well as the US region,were not associated with variation in female resident gender representation.

关键词： gender program director recruitment residency training

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Influence of erbium on structural,and charged particles,photons,and neutrons shielding properties of Ba_(1-x)Er_(x)SnO_(3) perovskite ceramics

引用

Journal of Rare Earths 2024年第4期42卷 724-732页

作者： m.K.h.Hamad Nidal Dwaikat m.H.A.mhareb m.I.Sayyed R.m.Hamad Y.S.m.Alajerami m.A.Almessiere Gameel Saleh Ahmad Hussein Alomari K.A.Ziq Department of Basic Sciences School of Social and Basics SciencesAl Hussein Technical UniversityKing Abdullah II St 242Amman11831Jordan Department of Physics College of Engineering and PhysicsInterdisciplinary Research Center for Advanced MaterialsKing Fahd University of Petroleum&MineralsDhahran31261Saudi Arabia Department of Physics College of ScienceImam Abdulrahman Bin Faisal UniversityP.O.Box 1982Dammam31441Saudi Arabia Basic and Applied Scientific Research center Imam Abdulrahman Bin Faisal UniversityP0.Box 1982Dammam31441Saudi Arabia Department of Physics Faculty of ScienceIsra UniversityAmman11622Jordan Department of Nuclear medicine Research Institute for Research and Medical Consultations(IRMC)Imam Abdulrahman Bin Faisal UniversityPo.Box 1982Dammam31441Saudi Arabia medical Imaging Department Applied Medical Sciences FacultyAl Azhar University-Gaza CityPo.Box 1277Palestine Department of Biophysics Institute for Research and Medical Consultations(IRMC)Imam Abdulrahman Bin Faisal UniversityPo.Box1982Dammam 31441Saudi Arabia Department of Biomedical Engineering College of EngineeringImam Abdulrahman Bin Faisal UniversityPo.Box 1982Dammam31441Saudi Energy&minerals Regulatory commission Amman11821Jordan

Five perovskite ceramics samples of Ba_(1-x)Er_(x)SnO_(3) with x=0.00,0.05,0.10,0.15,and 0.20 were synthesized using the conventional solid-state reaction *** prepared samples were characterized by X-ray diffraction(XRD),Fourier transforms infrared(FTIR),and UV-Vis *** shielding properties against ionizing radiation were also *** XRD analysis shows the perovskite cubic structure as the major phase in all *** FTIR reveals a distinctive band around 614-620 cm^(-1) ascribed to the antisymmetric O-Sn-O ***-Vis spectroscopy was used to determine the bandgap according to diffuse reflectance,and the results display a fixed enhancement in the bandgap from 3.2 to 3.3 eV for all ***-ray shielding properties of the synthesized samples were experimentally measured and compared with XcOm computational *** relative differences(Δ,%)between experimental and theo retical values are low and fall within the 0.446%-7.10%*** addition of Er leads to the enhanced density,neutron,and gamma shielding *** contrast,charged particles’shielding parameters gradually reduce with rising Er *** results suggest that Ba_(1-x)Er_(x)SnO_(3) samples can be used in different radiation shielding applications.

关键词： Perovskite ceramics Gamma ray shielding mass stopping power Rare earths

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：