Study on the optimal incident proton energy of ^(7)Li(p,n)^(7)Be neutron source for boron neutron capture therapy

Boron neutron capture therapy(BNCT)is recognized as a precise binary targeted radiotherapy technique that effectively eliminates tumors through the^(10)B(n,α)^(7)Li nuclear reaction.Among various neutron sources,accelerator-based sources have emerged as particularly promising for BNCT applications.The^(7)Li(p,n)^(7)Be reaction is highly regarded as a potential neutron source for BNCT,owing to its low threshold energy for the reaction,significant neutron yield,appropriate average neutron energy,and additional benefits.This study utilized Monte Carlo simulations to model the physical interactions within a lithium target subjected to proton bombardment,including neutron moderation by an MgF_(2)moderator and subsequent BNCT dose analysis using a Snyder head phantom.The study focused on calculating the yields of epithermal neutrons for various incident proton energies,finding an optimal energy at 2.7 MeV.Furthermore,the Snyder head phantom was employed in dose simulations to validate the effectiveness of this specific incident energy when utilizing a^(7)Li(p,n)^(7)Be neutron source for BNCT purposes.

基于Mathematica的平行光斜入射光栅衍射的模拟和可视化研究

光栅衍射作为大学物理的重要教学内容和教学难点,由于其理论推导和数学表达形式复杂,学生难以形成清晰的物理图像,导致课堂教学效果不理想。教材中仅对光垂直入射光栅时的衍射特性进行了讨论,但平行光斜入射光栅时的衍射特性却未被充分探讨,且这一领域的研究仍然有限。本文首先应用光的衍射理论推导出了平行光斜入射条件下单缝衍射和光栅衍射的光强分布表达形式,将单缝衍射和光栅衍射的研究由垂直入射推广到斜入射的情况。然后,应用Mathematica软件中的强大的交互式界面Manipulate,结合Initialization和Limit命令,对平行光斜入射情况下的单缝衍射和光栅衍射的光强分布进行了系统的模拟和仿真,分别绘制出单缝衍射的相对光强分布、多缝干涉的相对光强分布、光栅衍射的相对光强分布和衍射条纹分布情况。通过可视化过程,使学生深刻地理解光栅衍射的光强分布是单缝衍射和多缝干涉共同作用的结果,单缝衍射提供了光强分布的包络,而多缝干涉则决定了衍射条纹的具体亮暗变化,将抽象的光的衍射现象形象直观地动态演示出来,这有助于学生建立清晰的物理图像,深刻地理解单缝衍射和光栅衍射,极大地提高教学效果。

The force of oblique incident wave on the breakwater with a partially perforated wall

Wave forces induced by the interaction between the oblique incident wave and the breakwater with a partially perforated front wall is investigated. The fluid domain is divided into two sub-domains and the eigen-function expansion method is applied to expanding velocity potentials in each domain. In the eigen-expansion of the velocity potential, evanescent waves are included. Numerical results of the present model are compared with other theories and a good agreement can be found between them. Experimental data have been compared with the present theoretical results. The effect of the traverse wall on wave forces has been discussed in detail. On the basis of the linear wave theory, it is shown that in the range Of engineering practice, the incident angle of wave has small influence on wave forces on the unit length of perforated caisson.

Incident flow effects on the performance of piezoelectric energy harvesters from galloping vibrations

In this paper, we investigate experimentally the concept of energy har- vesting from galloping oscillations with a focus on wake and turbulence effects. The .harvester is composed of a unimorph piezoelectric cantilever beam with a square cross-section tip mass. In one case, the harvester is placed in the wake of another galloping harvester with the objective of determining the wake effects on the response of the harvester. In the second case, meshes were placed upstream of the harvester with the objective of investigating the effects of upstream turbulence on the response of the harvester. The results show that both wake effects and up- stream turbulence significantly affect the response of the harvester. Depending on the spacing between the two squares and the opening size of the mesh, wake and upstream turbulence can positively enhance the level of the harvested power.

A Method to Determine the Incident Wave Boundary Conditions and Its Application

When studying the harbor water tranquility, cases are often confronted as that the verification point is not located on the generation line or that the angle between the generation line and the isobath is so large that the differences of the wave climates along the generation line can not be ignored. For these cases, the incident boundary conditions are difficult to evaluate. In order to solve this problem, a combined wave model is developed in the present paper based on the Boussinesq equation and the wave action balance equation. Instead of the one-line wave generation method, a multi-line generation method is proposed for the combined model. Application of this method is given to a case that the harbor is designed with two entrances and the angle between the generation line and the isobath is large and the results are shown reasonable. We suggest that the wave generation method on multi-lines might also be introduced to the wave physical model as the replacement for the one-line generation method.

A Literature Review on Freeway Traffic Incidents and Their Impact on Traffic Operations

Congestion on the freeway is more frequent due to several traffic incidents, namely traffic accidents, debris on the road, vehicle breakdown, and collision with guardrails than any other incidents. These, in turn, affect the operational performance of the freeway by increasing queue length, volume, and density. Consequently, effective freeway management strategies can help to minimize these impacts. The study investigates and summarizes existing studies to identify the reasons for and effects of the traffic incidents. Attention is given to the available solutions of the freeway traffic incidents management. The ultimate goal of this study is to identify the gaps which are not yet addressed to improve the operational effectiveness of the freeway. This study was conducted through a comprehensive literature review of existing refereed publications, established standards, and formal guidelines. Literature was sought through the Transport Research International Documentation (TRID) database, IEEE Transactions database, and google scholar search engine. Research focusing on freeway traffic incidents is a growing concern in transportation operations, as transportation network performance depends on it. Due to the advancement of technology, emerging vehicle technologies like connected vehicles have the potential to address these problems affecting the US transportation system and revolutionize mobility in the future. The study can serve as a reference for the researchers that are involved in freeway traffic operations.

GNSS array receiver faced with overloaded interferences:anti-jamming performance and the incident directions of interferences

Anti-jamming solutions based on antenna arrays enhance the anti-jamming ability and the robustness of global navigation satellite system(GNSS)receiver remarkably.However,the performance of the receiver will deteriorate significantly in the overloaded interferences scenario.We define the overloaded interferences scenario as where the number of interferences is more than or equal to the number of antenna arrays elements.In this paper,the effect mechanism of interferences with different incident directions is found by studying the anti-jamming performance of the adaptive space filter.The theoretical analysis and conclusions,which are first validated through numerical examples,reveal the relationships between the optimal weight vector and the eigenvectors of the input signal autocorrelation matrix,the relationships between the interference cancellation ratio(ICR),the signal to interference and noise power ratio(SINR)of the adaptive space filter output and the number of interferences,the eigenvalues of the input signal autocorrelation matrix.In addition,two simulation experiments are utilized to further corroborate the theoretical findings through soft anti-jamming receiver.The simulation results match well with the theoretical analysis results,thus validating the effect mechanism of overloaded interferences.The simulation results show that,for a four elements circular array,the performance difference is up to 19 dB with different incident directions of interferences.Anti-jamming performance evaluation and jamming deployment optimization can obtain more accurate and efficient results by using the conclusions.

Properties of Ternary One Dimensional Plasma Photomic Crystals for an Obliquely Incident Electromagnetic Wave Considering the Effect of Collisions in Plasma Layers

An analytical study is presented on the modal dispersion characteristics, group velocity, and effective group, as well as the phase index of a ternary one dimensional plasma photonic crystal for an obliquely incident electromagnetic wave considering the effect of collisions in plasma layers. The dispersion relation is derived by using the transfer matrix method and the boundary conditions based on electromagnetic theory. The dispersion curves are plotted for both the normal photonic band gap structure and the absorption photonic band gap structure. It is found that the increase in the angle of incidence shifts the photonic band gap toward higher frequencies. Also, the cutoff frequency is independent of collisions.

A short P-wave duration is associated with incident heart failure in the elderly: a 15 years follow-up cohort study

BACKGROUND Early identification of patients at risk of congestive heart failure(HF)may alter their poor prognosis.The aim was therefore to test whether simple electrocardiographic variables,the P-wave and PR-interval,could predict incident HF.METHODS The PIVUS(Prospective Investigation of the Vasculature in Uppsala Seniors)study(1016 individuals all aged 70 years,50%women)was used to identify predictors of HF.Subjects with prevalent HF,QRS duration≥130 ms,atrial tachyar-rhythmias,implanted pacemaker/defibrillator,second-and third-degree atrioventricular block or delta waves at baseline were excluded.Cox proportional hazard analysis was used to relate the PR interval,P-wave duration(Pdur)and amplitude(Pamp),measured in lead V1,to incident HF.Adjustment was performed for gender,RR-interval,beta-blocking agents,systolic blood pressure,body mass index and smoking.RESULTS Out of 836 subjects at risk,107 subjects were diagnosed with HF during a follow-up of 15 years.In the multivariate analysis,there was a strong U-shaped correlation between Pdur in lead V1 and incident HF(P=0.0001)which was significant for a Pdur<60 ms[HR=2.75;95%CI:1.87-4.06,at Pdur 40 ms]but not for prolonged Pdur.There was no significant relationship between incident HF and the PR-interval or the Pamp.A Pdur<60 ms improved discrimination by 3.7%when added to the tradi-tional risk factors including sex,RR-interval,beta-blocking agents,systolic blood pressure,BMI and smoking(P=0.048).CONCLUSIONS A short Pdur,an easily measured parameter on the ECG,may potentially be a useful marker of future HF,enabling its early detection and prevention,thus improving outcomes.

The association between the baseline bone resorption marker CTX and incident dysglycemia after 4 years

Bone is an endocrine organ involved in modulating glucose homeostasis. The role of the bone formation marker osteocalcin （OCN） in predicting diabetes was reported, but with conflicting results. No study has explored the association between baseline bone resorption activity and incident diabetes or prediabetes during follow-up. Our objective was to examine the relationship between the baseline bone resorption marker crosslinked C-telopeptide of type I collagen （CTX） and glycemic dysregulation after 4 years. This longitudinal study was conducted in a university teaching hospital. A total of 195 normal glucose tolerant （NGT） women at baseline were invited for follow-up. The incidence of diabetes and prediabetes （collectively defined as dysglycemia） was recorded. A total of 128 individuals completed the 4-year study. The overall conversion rate from NGT to dysglycemia was 31.3%. The incidence of dysglycemia was lowest in the middle tertile [16.3% （95% confidence interval （CI）, 6.8%-30.70/0）] compared with the lower [31.0% （95% CI, 17.2%-46.1%）] and upper [46.5% （95% CI, 31.2%-62.6%）] tertiles of CTX, with a significant difference seen between the middle and upper tertiles （P = 0.002 5）. After adjusting for multiple confounding variables, the upper tertile of baseline CTX was associated with an increased risk of incident dysglycemia, with an odds ratio of 7.09 （95% CI, 1.73-28.99） when the middle tertile was the reference. Osteoclasts actively regulate glucose homeostasis in a biphasic model that moderately enhanced bone resorption marker CTX at baseline provides protective effects against the deterioration of glucose metabolism, whereas an overactive osteoclastic function contributes to an increased risk of subsequent dysglycemia.

Influence of seismic wave type and incident direction on the dynamic response of tall concrete-faced rockfill dams

Owing to the stochastic behavior of earthquakes and complex crustal structure,wave type and incident direction are uncertain when seismic waves arrive at a structure.In addition,because of the different types of the structures and terrains,the traveling wave effects have different influences on the dynamic response of the structures.For the tall concrete-faced rockfill dam(CFRD),it is not only built in the complex terrain such as river valley,but also its height has reached 300 m level,which puts forward higher requirements for the seismic safety of the anti-seepage system mainly comprising concrete face slabs,especially the accurate location of the weak area in seism.Considering the limitations of the traditional uniform vibration analysis method,we implemented an efficient dynamic interaction analysis between a tall CFRD and its foundation using a non-uniform wave input method with a viscous-spring artificial boundary and equivalent nodal loads.This method was then applied to investigate the dynamic stress distribution on the concrete face slabs for different seismic wave types and incident directions.The results indicate that dam-foundation interactions behave differently at different wave incident angles,and that the traveling wave effect becomes more evident in valley topography.Seismic wave type and incident direction dramatically influenced stress in the face slab,and the extreme stress values and distribution law will vary under oblique wave incidence.The influence of the incident direction on slab stress was particularly apparent when SH-waves arrived from the left bank.Specifically,the extreme stress values in the face slab increased with an increasing incident angle.Interestingly,the locations of the extreme stress values changed mainly along the axis of the dam,and did not exhibit large changes in height.The seismic safety of CFRDs is therefore lower at higher incident angles from an anti-seepage perspective.Therefore,it is necessary to consider both the seismic wave type and incident direction during seismic capacity evaluations of tall CFRDs.

Shaping the Wavefront of Incident Light with a Strong Robustness Particle Swarm Optimization Algorithm

We demonstrate a modified particle swarm optimization(PSO) algorithm to effectively shape the incident light with strong robustness and short optimization time. The performance of the modified PSO algorithm and genetic algorithm(GA) is numerically simulated. Then, using a high speed digital micromirror device, we carry out light focusing experiments with the modified PSO algorithm and GA. The experimental results show that the modified PSO algorithm has greater robustness and faster convergence speed than GA. This modified PSO algorithm has great application prospects in optical focusing and imaging inside in vivo biological tissue, which possesses a complicated background.

Hazard identification for equipment-related fatal incidents in the U.S.underground coal mining

Based on the number of fatalities per year, a persistent area of concern in mine safety continues to be equipment related. Data from the period 1995 through 2007 were studied in order to identify major hazards for underground mining equipment-related fatal incidents and to perform an analysis of those that occurred over the last 13 years. Reports on equipment-related fatal incidents were obtained from the Mine Safety and Health Administration （MSHA）. The results show that underground mining equipment including continuous miner, shuttle car, roof bolter, load-haul-dump （LHD）, Iongwall and hoisting contributed to a total of 69 mining-related fatalities. The study reveals that the major hazard for continuous mining equipment-related fatal incidents is ＂Failure of victim to respect equipment working area＂, while the highest number of fatalities for shuttle car is attributed to the hazard ＂Failure of mechanical components.＂ The study further reveals that the highest number of fatalities for roof bolter, LHD, and Iongwall are attributed to the hazards ＂Working under unsupported roof＂, ＂Failure of management to provide safe working conditions＂, and ＂Failure of mechanical components＂, respectively. It is determined that one fatality for the hoisting system is attributed to the hazard ＂Failure of mechanical components＂ and one to the hazard ＂Failure to follow safe maintenance procedure＂. Finally, approaches to prevention were also discussed in this paper.

Portable ultrasonography in mass casualty incidents:The CAVEAT examination

Ultrasonography used by practicing clinicians has been shown to be of utility in the evaluation of time-sensitive and critical illnesses in a range of environments,including pre-hospital triage,emergency department,and critical care settings.The increasing availability of lightweight,robust,user-friendly,and low-cost portable ultrasound equipment is particularly suited for use in the physically and temporally challenging environment of a multiple casualty incident(MCI).Currently established ultrasound applications used to identify potentially lethal thoracic or abdominal conditions offer a base upon which rapid,focused protocols using hand-carried emergency ultrasonography could be developed.Following a detailed review of the current use of portable ultrasonography in military and civilian MCI settings,we propose a protocol for sonographic evaluation of the chest,abdomen,vena cava,and extremities for acute triage.The protocol is two-tiered,based on the urgency and technical difficulty of the sonographic examination.In addition to utilization of well-established bedside abdominal and thoracic sonography applications,this protocol incorporates extremity assessment for long-bone fractures.Studies of the proposed protocol will need to be conducted to determine its utility in simulated and actual MCI settings.

Laboratory Study on the Interaction Between Regular Obliquely Incident Waves and Vertical Walls

The characteristics of wave forces are studied based on physical model tests with regular waves. The ratio of obliquely incident wave forces to normally incident wave forces on unit length of a vertical wall is related with various factors. A linear reduction of the mean force of obliquely incident waves is confirmed with an increase in the relative caisson length. Also the characteristics of reflection coefficient of diagonal waves are discussed.

Numerical Simulated Study on the Separation of Oblique Incident and Reflected Waves

The Goda's method of separating the frequency spectrum of the unidirectional incident and reflected waves is improved. The proposed method can be applied to the separation of oblique incident and reflected waves and the two wave gauges can be arranged in an arbitrary angle in front of a structure. When the projected distance of the two probes on the incident wave direction is the multiple ofthe half length of the incident waves, the singular problem will emerge by using the method. It is advised that when the projected distance of the two measured points on the incident wave direction is 0.05～0.45 times the wave length of peak frequency wave, good results can be obtained. The simulated resultant waves are separated by the method of numerical simulation and the separated wave spectra are basically corresponding to the target spectra input. The wave trains calculated by the separated incident and reflected wave frequency spectrum are approximated to the input wave trains and the reflected coefficient can be derived correctly. Therefore, the method proposed in this paper is reliable.

Incident analyses of frost heaving failure of municipal underground gas pipelines in cold regions of northern China

In the cold regions of northern China, incidents of municipal underground gas pipeline rupture and leakage occur quite fi-equently, aaost often in winter. To prevent harm to citizen safety and property, analysis of the causes of such cracking and leakage is therefore valuable. Two incident analyses are discussed here and the reasons why most of these types of cases occur dttring winter are clarified. Fhe effects of vehicle loadings above buried pipelines are calculated and compared with the effects and calculations of frost heaving forces. We demonstrate thtit when the soil layer above a pipeline freezes rapidly, the soil generates repeated frost heaving, which exerts heaving forces on the pipeline that can result in fatigue crack propagation and ultimate pipeline failure. Therefore, the incident induced 9y frost heaving is one of the primary reasons of gas pipeline failure. Based on these analyses, we present some recommendations pertaining to the proper design, construction, and management of gas pipelines.

A Survey of Bath Time Incidents Experienced by Mothers and Families of Children Aged 18 Months

Purpose: The potential dangers of infant bathing have an effect not only on the infant’s body and life but also on the formation of emotional bonds in the parent-child relationship. This study will explore actual dangers experienced by mothers and families. Method: We distributed an anonymous, self-reported questionnaire at infants’ 18-month health checkup, which was collected via postal service. 304 valid responses were received and formed our sample data. Descriptive statistical analysis was performed for each category surveyed. Inferential statistics were used to compare the dangerous incidents experienced with regard to differences between primipara/multipara and the presence/absence of guidance concerning such incidents. This study was approved by the research ethics committees of the affiliated university. Results: 70% of mothers and families experienced incidents while bathing their infants, with the most common incidents consisting of, in order of frequency, near immersion of the face, actual immersion of the face, and falling into the bath. The most common situations reported when incidents occurred were bathing the infant by oneself, the infant moving unexpectedly, or taking care of other children, in that order. Approximately 70% of mothers and families had not received instruction on the potential dangers or how to prevent them. Conclusion: This study has elucidated the dangerous situations experienced in the course of bathing infants in the home and the measures taken to prevent such situations. Instructive tools are needed which can be used to easily provide mothers and families with correct information.

A Universal Formula for the Secondary Electron Yield of Metals at an Incident Angle of θ

Based on the main physical processes,we deduce the relationships among the incident energy Wp0 of the primary electron,the number of released secondary electrons(i.e.δ_(PEθ))per primary electron entering the metal at incident angleθand the angleθitself.In addition,the relationship ofδPEθatθ=0°,i.e.δ_(PE0),with Wp0 is determined.From the experimental results,the relationship of the ratio atθ=0°,i.e.β_(0) which is the ratio of the average number of released secondary electrons generated by a single primary electron backscattered at the metal surface to that generated by a single primary electron entering the metal,with Wp0 is determined.Moreover,the relationships among the ratioβθ,Wp0 andθare obtained.Based on the relationships among the secondary electron yield atθ(i.e.δθ),the yield atθ=0°(i.e.δ_(0)),the backscattering coefficient atθ(i.e.η_(θ)),the coefficient atθ=0°(i.e.η0),δ_(PEθ)andδ_(PE0),we deduce the universal formula forδ_(θ),δ_(0),η_(θ),η_(0),and W_(p0) for the primary electrons at an incident energy of 2–10 keV.The secondary electron yields calculated from the universal formula and the experimental yields of some metals are compared,and the results suggest that the proposed formula is universal for estimation of secondary electron yields atθ=0°−80°.

The Culture of Incident Reporting and Feedback: A Cross-Sectional Study in a Hospital Setting

A safety culture where incidents have been reported and feedback given is essential to detect and understand system failures. The aims of this study were to examine the culture of incident reporting and feedback (the incident culture) in a hospital setting, and the associations between the incident culture and other dimensions of the safety culture. A cross-sectional study was carried out with the instrument Hospital Survey on Patient Safety Culture (HSOPSC) within 16 units in six somatic hospitals at a Norwegian Hospital Trust. Units with identical specialities across the hospitals constitute a clinic. HSOPSC measures the health care personnel’s perception of the safety culture, seven safety dimensions at the unit level, three at the hospital level and four outcome measures. The outcome measures “Frequency of event reporting” and the dimension “Feedback and communication about error” were combined into the variable “incident culture”, score 1 - 5. A positive score was defined as ≥ 4.0. This study included 631 health care personnel. The mean score for the incident culture was 3.10 (SD 0.65) with significant differences between the clinics, and the hospitals. The strongest predictors for the incident culture were the dimensions “Communication openness” (linear regression slope B 0.470;95% CI 0.398 to 0.543;p < 0.001), “Manager expectations and actions promoting safety” (B 0.378;95% CI 0.304 to 0.453;p < 0.001), “Organisational learning and continuous improvement” (B 0.374;95% CI 0.293 to 0.455;p < 0.001) and “Teamwork across hospital units” (B 0.360;95% CI 0.261 to 0.459;p < 0.001). In this study, the incident culture needed improvements. To improve the incident culture, the attention may be directed towards developing and maintaining a culture of open communication, management that promotes safety, and a learning organisation and teamwork between the units.