Use of Donkeys to Guard Sheep and Goats in Texas

Though livestock guarding dogs have received considerable attention in recent years, other animals including donkeys (Equus asinus) are being used to protect sheep and goats from predation by coyotes (Canis latrans). In Texas many ranchers prefer donkeys due to low cost, relatively small maintenance requirements, and compatibility with other predator control methods. This paper describes husbandry practices for use of guard donkeys and relates rancher accounts of their effectiveness in protecting sheep and goats

Mentoring undergraduate civil engineering students

On enrolment at university, undergraduate civil engineering students begin their journey towards a professional career. Associating with graduate engineers throughout their studies provides students with potential role models and assists them to accustom progressively to the industry. Whilst the procurement of guest practitioners to deliver workshops and lectures remains buoyant, opportunities for students to secure summer placements within the civil engineering sector, has been problematic since the 2008 financial crisis. Graduate mentoring of student mentees can help to bridge the shortage of vocational placements. This paper discusses the results from a graduate mentoring initiative involving third year (n=345) civil & environmental engineering (CEE) student mentees, 83 graduate mentors and 31 employers. The results show that the student mentees overwhelmingly support and validate the opportunities that this initiative has provided. On completion of their mentoring meetings, and on return to their fourth year of their studies, the majority of the students commit to making behavioural and attitudinal changes regarding their own continued professional development (CPD)

Experimental assessment of vapour chamber heat spreader implementation in avionic cooling

Avionic thermal management is quickly becoming the limiting factor of aircraft performance and reliability, particularly prevalent with ageing airframes. While the increasing power density of avionic components requires a greater heat removal capacity for a given geometric module size, supplementary generation of cooling airflow is detrimental to engine and aircraft performance. This paper looks at improving the heat removal efficiency of forced convection cooled avionic modules by reducing the thermal resistance between the avionic component and module heat exchanger. The implementation of two-phase high thermal conductivity materials, such as Vapour Chamber Heat Spreaders (VCHS), embedded within the avionic module chassis act to improve heat exchanger isothermalisation, improving the effective heat transfer area. A bespoke test rig has been manufactured to experimentally compare a pure aluminium and embedded VCHS avionic chassis for heat removal capability. When considering a single circuit card, a direct mass flow rate reduction of between 22% and 65% is achieved with embedded VCHS over a pure aluminium chassis. Base plate isothermalisation is improved by 9%, generating a reduction in component temperature of 8% to 12%. As the number of heat sources increase, the performance improvements decrease. When testing with three circuit cards mass flow rate savings are reduced to between 14% and 26%. The concluding performance characteristic of the embedded VCHS avionic base plate is the insensitivity to the way thermal energy is coupled to it. Across all testing, the localised heat removal was never further than 3.5% from the averaged plate performance

Assessment of vapour chamber heat spreader implementation for avionic module thermal management

Thermal management of aircraft heat loads is quickly becoming a limiting factor of vehicle performance and reliability. This paper details improvements in forced-convection cooled avionic module heat removal efficiency with the implementation of two-phase high thermal conductivity Vapour Chamber Heat Spreaders (VCHS). A bespoke test rig provides experimental thermal comparisons of an aluminium and embedded VCHS avionic heat exchanger. The experimental results validate a numerical thermal resistance network, which is utilised to simulate more representative avionic chassis geometries. The VCHS dramatically reduces thermal variation in circuit card and avionic heat exchanger exhaust temperatures. Increased isothermalisation of the heat exchanger greatly increases effective heat transfer area in comparison to a traditional aluminium chassis. The VCHS acts as a very effective thermal buffer between the avionic circuit cards and coolant airflow, allowing a more predictable avionic thermal behaviour irrespective of circuit card architecture. The improved heat rejection capability allows either a substantial increase in avionic growth capacity (increased power output for a fixed exhaust temperature) or a substantial reduction in mass flow rate (reduced demand on vehicle thermal management system). An avionic growth capacity of up to 58% is achieved with representative thermal loading conditions

Systematic Multi-Epoch Monitoring of LkCa 15: Dynamic Dust Structures on Solar-System Scales

We present the highest angular resolution infrared monitoring of LkCa 15, a young solar analog hosting a transition disk. This system has been the subject of a number of direct imaging studies from the millimeter through the optical, which have revealed multiple protoplanetary disk rings as well as three orbiting protoplanet candidates detected in infrared continuum (one of which was simultaneously seen at H$\alpha$). We use high-angular-resolution infrared imaging from 2014-2020 to systematically monitor these infrared signals and determine their physical origin. We find that three self-luminous protoplanets cannot explain the positional evolution of the infrared sources, since the longer time baseline images lack the coherent orbital motion that would be expected for companions. However, the data still strongly prefer a time-variable morphology that cannot be reproduced by static scattered-light disk models. The multi-epoch observations suggest the presence of complex and dynamic substructures moving through the forward-scattering side of the disk at $\sim20$ AU, or quickly-varying shadowing by closer-in material. We explore whether the previous H$\alpha$ detection of one candidate would be inconsistent with this scenario, and in the process develop an analytical signal-to-noise penalty for H$\alpha$ excesses detected near forward-scattered light. Under these new noise considerations, the H$\alpha$ detection is not strongly inconsistent with forward scattering, making the dynamic LkCa 15 disk a natural explanation for both the infrared and H$\alpha$ data.Comment: 24 pages, 11 figures, accepted for publication in Ap

Perception of Radiation Exposure and Risk Among Patients, Medical Students, and Referring Physicians at a Tertiary Care Community Hospital

AbstractBackgroundIt is important for physicians to be aware of the radiation doses as well as the risks associated with diagnostic imaging procedures that they are ordering.MethodsA survey was administered to patients, medical students, and referring physicians from a number of specialties to determine background knowledge regarding radiation exposure and risk associated with commonly ordered medical imaging tests.ResultsA total of 127 patients, 32 referring physicians, and 30 medical students completed the survey. The majority of patients (92%) were not informed of the radiation risks associated with tests that they were scheduled to receive and had false perceptions about the use of radiation and its associated risks. Physicians and medical students had misconceptions about the use of ionizing radiation in a number of radiologic examinations; for example, 25% and 43% of physicians and medical students, respectively, were unaware that interventional procedures used ionizing radiation, and 28% of physicians were unaware that mammography used ionizing radiation. Computed tomographies and barium studies were thought to be associated with the least ionizing radiation among physicians.ConclusionThere is a need for educating the public, medical students, and referring physicians about radiation exposure and associated risk so that (1) patients receiving multiple medical imaging tests are aware of the radiation that they are receiving and (2) physicians and future physicians will make informed decisions when ordering such tests to limit the amount of radiation that patients receive and to promote informed consent among patients

Counselling in primary care : a systematic review of the evidence

Primary objective: To undertake a systematic review which aimed to locate, appraise and synthesise evidence to obtain a reliable overview of the clinical effectiveness, cost-effectiveness and user perspectives regarding counselling in primary care. Main results: Evidence from 26 studies was presented as a narrative synthesis and demonstrated that counselling is effective in the short term, is as effective as CBT with typical heterogeneous primary care populations and more effective than routine primary care for the treatment of non-specific generic psychological problems, anxiety and depression. Counselling may reduce levels of referrals to psychiatric services, but does not appear to reduce medication, the number of GP consultations or overall costs. Patients are highly satisfied with the counselling they have received in primary care and prefer counselling to medication for depression. Conclusions and implications for future research: This review demonstrates the value of counselling as a valid choice for primary care patients and as a broadly effective therapeutic intervention for a wide range of generic psychological conditions presenting in the primary care setting. More rigorous clinical and cost-effectiveness trials are needed together with surveys of more typical users of primary care services

Development of a full scale experimental and simulation tool for environmental control system optimisation and fault detection

This paper documents the installation of a fast jet military aircraft Environmental Control System (ECS) ground test facility. The system used in this case is a bleed-air driven two-wheel bootstrap cycle with low pressure water extraction. The facility allows the ECS to be run at conditions similar to those in the aircraft during ground operation. Data from the rig is presented and used to validate a 1-D thermodynamic model. The relationships between aircraft altitude and speed against ECS Coefficient of Performance and system heat rejection are presented, seamlessly utilising both experimental and modelled data. Furthermore, a scenario depicting a ram air blockage in the secondary heat exchanger demonstrates the system’s ability to mask faults. The physical system is used for component-level analysis, whilst the model extends this to system-level. General attributes of the system operation are discussed