The Fundamental Resonant Frequency and Radiation Characteristics of Wide Angle Conical Antennas

Of recent interest for simple compact pulse power systems is the self-resonant wide-angle conical antenna. In its typical application, this antenna will radiate a transient damped sine wave pulse whose center frequency is the fundamental resonant frequency of the antenna. In order to properly design such an antenna, it is important to know the dependence of the fundamental resonant frequency on both slant height and half cone angle. Theoretical analysis of this type of antenna is typically based on the mode theory of antennas (as derived by S.A. Schelkunoff) in which the structure is treated as a conical transmission line. The theory is quite complicated and leads to two sets of equations involving infinite sums which must be solved simultaneously; this is a difficult task. In this effort, the accuracy of simplifications to the theory in predicting the fundamental resonant frequency of a wide angle conical antenna was explored by comparing the results obtained based on these approximations to experimental results as well as the results of numerical simulation using CST Microwave Studio. Good agreement is obtained between the simulated and experimentally measured results. It was found that a first order approximation to the theory as derived by C. Papas and R. King, while otherwise very useful, is insufficient to predict the fundamental resonant frequency of a wide angle conical antenna with reasonable accuracy; however, a second order approximation as derived by P.D.P. Smith does yield results that are in good agreement with results of experiment and simulation. It was found that the relationship between slant height (\u2113) and wavelength (λ) at the fundamental resonant frequency, for wide half cone angles, corresponds more closely to \u2113= λ /8 than the expected \u2113= λ /4. Of primary interest was the fundamental resonant frequency as a function of slant height and half cone angle; however, the peak radiated electric field and the radiation efficiency of the conical antenna as a function of half cone angle was also explored

Planning for the perfect storm: perceptions of UK mental health professionals on the increasing impacts of climate change on their service users

Introduction Climate change poses a considerable risk of further increasing the world's mental health burden. The ways that, and extent to which, climate change is affecting mental health service users is poorly known. Mental health professionals (MHP)s' views on the nature of climate-related distress and the need for specialist training to support service users is undetermined globally. Methods A questionnaire survey was disseminated to an opportunity sample of MHPs based in the United Kingdom (UK). It investigated whether MHPs perceived that the number of service users mentioning climate change as affecting their mental health or emotional distress had increased in the five years prior to 2021, and if they believe it will increase further. The survey explored MHPs’ perceptions of the influence of climate change on service users’ mental health needs, if they perceive this to be rational, and if they feel adequately prepared to manage climate change related mental health problems or emotional distress. Results We surveyed 75 MHPs, including professionals in psychotherapy (38), psychology (19), psychiatry (6). MHPs reported a significant increase in the perceived prevalence of mental health problems or emotional distress related to climate change, believing this increase will continue. MHPs reported a range of impacts on service users due to climate change, typically viewed as a rational response. MHPs felt equipped to manage the consequences of climate change but would benefit from specific training. Conclusions Our results indicate an increasing incidence of climate-related emotional distress among service users as perceived by MHPs. The expectation among professionals is that this service need is here now but will continue to increase in the future, with potential implications for the provision of training

Listening to mental health crisis needs at scale: using Natural Language Processing to understand and evaluate a mental health crisis text messaging service

The current mental health crisis is a growing public health issue requiring a large-scale response that cannot be met with traditional services alone. Digital support tools are proliferating, yet most are not systematically evaluated, and we know little about their users and their needs. Shout is a free mental health text messaging service run by the charity Mental Health Innovations, which provides support for individuals in the UK experiencing mental or emotional distress and seeking help. Here we study a large data set of anonymised text message conversations and post-conversation surveys compiled through Shout. This data provides an opportunity to hear at scale from those experiencing distress; to better understand mental health needs for people not using traditional mental health services; and to evaluate the impact of a novel form of crisis support. We use natural language processing (NLP) to assess the adherence of volunteers to conversation techniques and formats, and to gain insight into demographic user groups and their behavioural expressions of distress. Our textual analyses achieve accurate classification of conversation stages (weighted accuracy = 88%), behaviours (1-hamming loss = 95%) and texter demographics (weighted accuracy = 96%), exemplifying how the application of NLP to frontline mental health data sets can aid with post-hoc analysis and evaluation of quality of service provision in digital mental health services

How I do it: Minimally invasive Cox-Maze IV procedure

Clinical vignette Our patient is a 66-year-old female with a 2-year history of atrial fibrillation (AF) and mitral valve prolapse who presented with dyspnea on exertion. She was found to be in AF upon her admission electrocardiogram. A transthoracic echocardiogram was performed demonstrating moderate-to-severe mitral regurgitation (MR) with a left atrial (LA) diameter of 5.1 cm and normal left ventricular (LV) function. After completion of her workup, it was decided that the patient would best be treated by a minimally invasive Cox-Maze IV (CMIV) and concomitant mitral valve procedure given her significant MR and symptoms. This article and accompanying video will discuss how the minimally invasive CMIV procedure is performed. Surgical technique

Microwave Spectroscopy

Contains reports on three research projects

Developing global recommendations for action on climate change and mental health across sectors: a Delphi-style study

Climate change is causing far-reaching yet underappreciated worsening of outcomes across the mental health and wellbeing spectrum. Despite increasing attention to the mental health impacts of climate change, an absence of a clear, cross-sectoral agenda for action has held back progress against the dual and interconnected challenges of supporting human and planetary health. This study aims to serve as an essential first step to address this gap. Harnessing the expertise of a diverse panel of 61 participants, representing 24 nationalities, this study developed and prioritized recommendations for action on climate change and mental health across the relevant sectors of research, policy, healthcare and the third sector, and used a Delphi-style methodology to examine their feasibility and importance. Broadly, the prioritized recommendations highlighted the need to expand the evidence base, work collaboratively across sectors, and raise awareness. While broadly there was consensus on recommendation importance, there was greater variation in the reported feasibility of the recommendations, which differed across settings. Other common themes included the need for cultural and resource contextualization, raising awareness of and addressing mental health co-benefits via climate action, and working with communities with lived experience to develop and implement the findings. As there may be some interdependencies between the recommendations, further work needs to identify how best to implement them. The recommendations serve as a robust and evidence-based framework that can be used as a foundation to devise locally appropriate, concrete implementation strategies matching levels of need and resource. These also serve as a clear call to action for investment from leaders across sectors to ensure they are realized

Thermodynamic analysis of the Quantum Critical behavior of Ce-lattice compounds

A systematic analysis of low temperature magnetic phase diagrams of Ce compounds is performed in order to recognize the thermodynamic conditions to be fulfilled by those systems to reach a quantum critical regime and, alternatively, to identify other kinds of low temperature behaviors. Based on specific heat ($C_m$) and entropy ($S_m$) results, three different types of phase diagrams are recognized: i) with the entropy involved into the ordered phase ($S_{MO}$) decreasing proportionally to the ordering temperature ($T_{MO}$), ii) those showing a transference of degrees of freedom from the ordered phase to a non-magnetic component, with their $C_m(T_{MO})$ jump ($\Delta C_m$) vanishing at finite temperature, and iii) those ending in a critical point at finite temperature because their $\Delta C_m$ do not decrease with $T_{MO}$ producing an entropy accumulation at low temperature. Only those systems belonging to the first case, i.e. with $S_{MO}\to 0$ as $T_{MO}\to 0$, can be regarded as candidates for quantum critical behavior. Their magnetic phase boundaries deviate from the classical negative curvature below $T\approx 2.5$\,K, denouncing frequent misleading extrapolations down to T=0. Different characteristic concentrations are recognized and analyzed for Ce-ligand alloyed systems. Particularly, a pre-critical region is identified, where the nature of the magnetic transition undergoes significant modifications, with its $\partial C_m/\partial T$ discontinuity strongly affected by magnetic field and showing an increasing remnant entropy at $T\to 0$. Physical constraints arising from the third law at $T\to 0$ are discussed and recognized from experimental results

Radio-Frequency Spectroscopy

Contains reports on three research projects