The connection between entropy and the absorption spectra of Schwarzschild black holes for light and massless scalar fields

We present heuristic arguments suggesting that if EM waves with wavelengths somewhat larger than the Schwarzschild radius of a black hole were fully absorbed by it, the second law of thermodynamics would be violated, under the Bekenstein interpretation of the area of a black hole as a measure of its entropy. Thus, entropy considerations make the well known fact that large wavelengths are only marginally absorbed by black holes, a natural consequence of thermodynamics. We also study numerically the ingoing radial propagation of a scalar field wave in a Schwarzschild metric, relaxing the standard assumption which leads to the eikonal equation, that the wave has zero spatial extent. We find that if these waves have wavelengths larger that the Schwarzschild radius, they are very substantially reflected, fully to numerical accuracy. Interestingly, this critical wavelength approximately coincides with the one derived from entropy considerations of the EM field, and is consistent with well known limit results of scattering in the Schwarzschild metric. The propagation speed is also calculated and seen to differ from the value $c$, for wavelengths larger than $R_{s}$, in the vicinity of $R_{s}$. As in all classical wave phenomena, whenever the wavelength is larger or comparable to the physical size of elements in the system, in this case changes in the metric, the zero extent 'particle' description fails, and the wave nature becomes apparent.Comment: 14 Pages, 4 figures. Accepted for publication in the Journal Entrop

Non‐invasive recordings of fetal electrocardiogram during pregnancy using electric potential sensors

In this letter, we report the early detection of fetal cardiac electrical activity recorded from the maternal abdomen non-invasively. We developed a portable and non-invasive, prototype based on electric potential sensing technology to monitor both: the mother and fetal heart activity during pregnancy. In this proof of principle demonstration, we show the suitability of our technology to monitor the fetal heart development starting at week twenty, when the fetus heart is approximately one-tenth the size of an adult’s heart. The study was conducted for ten weeks to demonstrate how the maturation of the fetus leads to a change on the heart rate dynamics as it approaches birth. Importantly, electrocardiogram information is presented without any post processing given that our device eliminates the requirement of signal conditioning algorithms such as having to un-mix both, the maternal and fetal cardiac waveforms. The provided ECG trace allows extracting the heart rate and other heart activity parameters useful for further diagnostics. Finally, our device does not require any gels to be applied so movement induced potential is eliminated. This technology has the potential to be used for determining possible heart related congenital disorders during pregnancy

Distribution and Conservation Status of Antillean Manatees (Trichechus manatus manatus) in Honduras

The Antillean manatee, Trichechus manatus manatus, is among the most threatened mammals in Honduras, yet the last published study is from 1980. Since then, the North Coast of Honduras has experienced rapid population growth and land cover change possibly causing habitat loss for manatees. We conducted aerial, boat, and interview surveys between 2005-2007 along the northern and remote eastern coasts of Honduras to assess the current status and distribution of manatees. In addition, we compiled all available data on manatee mortality from museum specimens, unpublished reports, and interviews to determine current threats. We averaged 1.2 manatee sightings per survey hour during six flights along the North Coast in March-April 2006 during 14.4 aerial survey hours. Sightings were mainly clustered in Cuero y Salado Wildlife Refuge (CSWR) and Rios Chapagua and Aguan, which we indentify as important conservation areas. Our total and average sightings per survey hour in CSWR were much lower than those reported in 1979-80, in spite of the area being protected since 1987. Our interviews indicate that manatees are still present on the eastern coast (La Mosquitia), however we observed none during 14.5 survey hours in June 2005 and April 2007. The major cause of known mortality from 1970-2007, based on 26 records, was due to entanglement in fishnets. Despite local and federal protection, manatees are still poached and opportunistically caught in fishnets. While some efforts have been made by local NGOs to raise public awareness for manatees, a national conservation program is highly recommended to centralize and coordinate efforts

A novel non-invasive biosensor based on electric field detection for cardio-electrophysiology in zebrafish embryos

In this paper we report a novel biosensor based on electric field detection for recording cardiac electrical activity in zebrafish embryos. Using Sussex patented Electric Potential Sensing technology, a portable, non-invasive and cost-effective platform is developed to monitor in vivo electrocardiogram activity from the zebrafish heart. Cardiac activity signals were successfully detected from living zebrafish embryos starting at 3 days-post-fertilizatio

Quantification of aortic valvuloplasty catheter size using a metrology system based on brightfield microscopy

Balloon aortic valvuloplasty (BAV) has been employed [1] as a simple and low-cost treatment method for patients with severe aortic stenosis, for symptom palliation in patients considered inoperable, for aortic valve replacement and to select the proper transcatheter heart valve (THV) size. During THV implantation choosing the correct balloon size is paramount for minimizing the risks of coronary occlusion, annular damage or THV embolization. Current methods for selecting the proper balloon dimensions are based on transesophageal echocardiography and computed tomography requiring trained staff for image interpretation, expensive equipment and high doses of patient radiation exposure. Alternative methods propose the use of BAV to determine the correct THV size before its implantation [2]. The strategy is based on determining the BAV aortic anulus using a sterile caliper. Any slight pressure to the balloon may compromise the measurement accuracy. In this paper, we present a non-contact metrology system for BAV measurement based on bright field microscopy (BFM). The balloons under test (MedTek-22 and TrueDilation-22) were clamped vertically, employing a tension spring to restrict movement and ensure perpendicularity to the microscope optical axis. The BFM is based on an Olympus PLN 4X WD~18.5mm, NA 0.1, a tube lens (f~180mm) and a FL3-U3- 13S2M-CS camera mounted on top of a custom-made linear stage having a coarse resolution of ~ 3.3µm. Balloon expansion was performed using a Boston scientific Encore 26 inflation device. The balloons are made up of an outer shell with an internal catheter tube (Ø~2mm). By focusing the microscope on the internal tube, then moving the linear stage to refocus on the balloon outer wall, the inner tube to outer wall dimension (see figure inset) can be accurately measured using the linear stage digital readout. The balloon was inflated up to six times recording the pressure and radius at each stage of inflation (twice the amount required for THV). Our non-contact method preserves the catheter sterile conditions and allows the accurate measurement of the BAV anulus showing: a) repeatability of the achieved balloon radius within all the inflation rounds, b) accurate measurements with a standard error of ±200 µm c) and a variation of 1.38 ±0.0387 mm from the manufacturer data. Knowing the exact balloon dimensions is crucial for avoiding the adverse consequences of THV oversizing. Our method may potentially improve the safety and efficacy of THV implantation

Moving forward through consensus: protocol for a modified Delphi approach to determine the top research priorities in the field of orthopaedic oncology.

IntroductionOrthopaedic oncology researchers face several obstacles in the design and execution of randomised controlled trials, including finite fiscal resources to support the rising costs of clinical research and insufficient patient volume at individual sites. As a result, high-quality research to guide clinical practice has lagged behind other surgical subspecialties. A focused approach is imperative to design a research programme that is economical, streamlined and addresses clinically relevant endpoints. The primary objective of this study will be to use a consensus-based approach to identify research priorities for international clinical trials in orthopaedic oncology.Methods and analysisWe will conduct a 3-phase modified Delphi method consisting of 2 sequential rounds of anonymous web-based questionnaires (phases I and II), and an in-person consensus meeting (phase III). Participants will suggest research questions that they believe are of particular importance to the field (phase I), and individually rate each proposed question on 5 criteria (phase II). Research questions that meet predetermined consensus thresholds will be brought forward to the consensus meeting (phase III) for discussion by an expert panel. Following these discussions, the expert panel will be asked to assign scores for each research question, and research questions meeting predetermined criteria will be brought forward for final ranking. The expert panel will then be asked to rank the top 3 research questions, and these 3 research questions will be distributed to the initial group of participants for validation.Ethics and disseminationAn ethics application is currently under review with the Hamilton Integrated Research Ethics Board in Hamilton, Ontario, Canada. The results of this initiative will be disseminated through peer-reviewed publications and conference presentations

Effect of Carbon Dioxide Concentration on the Growth Response of Chlorella vulgaris Under Four Different Led Illumination

This experiment examined the growth response of Chlorella vulgaris exposed to CO2 concentrations increasing from ambient to 8.5% and under white, blue, red and red-blue lights after 15 days incubation. Biomass production increased with increasing CO2 concentrations under all light sources. The highest biomass production, 1.59 g L-1, was obtained when the algae were supplied with 8.5% CO2 and exposed to white light. Biomass production under blue, red and red+blue light was 1.53 g L-1, 0.45 g L-1 and 1.27 g L-1, respectively. The research suggests that C. vulgaris is not able to adapt production of its photosynthetic pigments to absorb light sources different that it is normally has evolved to

Cinq façons de maîtriser la logistique organisationnelle, les backends et les flux de travail

Organizational backends and logistics are often complex and many institutions set-up their workflows based on manual and tedious processes that negatively shape their interactions with stakeholders. Incorporating new technologies can be intimidating, however there exists a plethora of financially and technically accessible resources, that don’t require any coding knowledge, that institutions can utilize to enhance their organizational workflow and stakeholder experience. Guided by our own learning experiences in optimal logistical set-up and user design, we wish to highlight five effective and easily implementable tricks to aid higher institutions and student groups in healthcare accomplish their administrative duties.Les backends et la logistique des organisations sont souvent complexes et de nombreuses institutions établissent leurs flux de travail sur la base de processus manuels et fastidieux qui influencent négativement leurs interactions avec les parties prenantes. L'intégration de nouvelles technologies peut être intimidante, mais il existe une pléthore de ressources financièrement et techniquement accessibles, qui ne nécessitent aucune connaissance en codage, que les institutions peuvent utiliser pour améliorer leur flux de travail organisationnel et l'expérience des parties prenantes. Guidés par nos propres expériences d'apprentissage en matière de mise en place d'une logistique optimale et de conception pour l'utilisateur, nous souhaitons mettre en avant cinq astuces efficaces et faciles à mettre en œuvre pour aider les établissements supérieurs et les groupes d'étudiants en soins de santé à accomplir leurs tâches administratives