437 research outputs found
Achieving international consensus for the prevention of orthopaedic wound blistering: results of a Delphi survey
No full textThis article presents the results of an international 2 stage Delphi survey carried out via e-mail to achieve consensus as to the most effective postoperative wound management to prevent blistering and other complications. Seventeen prospective participants were invited to be members of the Delphi Panel of which 13 agreed to be involved. The panel suggested that an ideal wound dressing would conform easily to the wound, be easy to apply and remove, allow for swelling and minimise pain on removal. Participants were in agreement that the primary wound dressing should be left in situ for as long as possible, providing there was no excessive oozing or signs of infection. The authors recognise that the Delphi Panel was relatively compact; however, the study arguably provides some useful data that can be used to identify the consequences of wound blistering and important factors that need to be considered when choosing a wound dressing to prevent blistering
Recommended from our members
Discovery and Demographics of Hot Planets Orbiting Hot Stars
No full textSurveys dedicated to detecting exoplanets via the transit and radial velocity methods have revolutionized our understanding of planet formation and evolution by revealing the the prevalence of planets orbiting close to their stars. Transit surveys have been especially groundbreaking due to their abilities to discover large quantities of planets with small orbital separations, which can they be further characterized via transmission spectroscopy, emission spectroscopy, and thermal phase curve observations to reveal details about their atmospheres and surfaces. In recent years, the Transiting Exoplanet Survey Satellite (TESS) has provided the opportunity to expand these techniques into entirely new regimes, due to its ability to search for transiting planets around a greater variety of stars and around brighter stars that are more amendable to follow-up observations. This thesis focuses on the utilization of TESS data to search for and study the demographics of these planets.First, I present TRICERATOPS, a tool designed to statistically validate transiting exoplanets and identify likely astrophysical false positives in TESS data. To statistically validate a transiting exoplanet is to confirm its planetary nature by ruling out plausible false positive scenarios, such as those that arise when multiple stars are blended together in the data. This is a particularly pertinent problem for TESS, which is equipped with relatively low-resolution cameras that often cannot distinguish light originating from individual stars, especially in crowded fields. I discuss the design and efficacy of TRICERATOPS, demonstrating that it is an effective tool for identifying the most promising planet candidates detected by TESS and prioritizing follow-up observations with both ground-based and space-based telescopes.Next, I use TRICERATOPS and an array of ground-based follow-up observations to validate 13 hot and potentially terrestrial planets detected by TESS. These planets are unlike any rocky bodies in the Solar System; they orbit their stars at distances of only a few stellar radii and are so highly irradiated that many are expected to have molten surfaces. Their high temperatures also mean that they emit infrared light at levels detectable by JWST. Emission spectroscopy and thermal phase curve observations of these worlds can reveal the presence and composition of an atmosphere, measure Bond albedo, and calculate heat redistribution properties. Prior to TESS, very few of these types of planets were known around bright stars amenable to JWST observations. This sample therefore facilitates the investigation of hot Earth-size worlds at a population level.Finally, I conduct a search for planets smaller than Saturn orbiting A-type stars. A-type stars, which are roughly twice as massive and nearly twice as hot as Sun-like stars, have historically been avoided by transit and radial velocity surveys due to their large radii and rapid rotation rates, which hinder our ability to detect planets around them. As a consequence, early transit surveys like the Kepler mission acquired very little data of these stars, limiting our understanding of planet demographics to stars like the Sun and cooler. By observing all bright stars across nearly the entire sky, TESS has provided the best opportunity yet to search for small planets orbiting relatively hot stars. Through this search, I discover and validate a single planet: HD 56414 b, a Neptune-size planet orbiting one of the hottest planet-hosting stars known to date on a 29-day orbital period. The orbital period of this planet is long compared to the typical planet detected by TESS, suggesting that Neptune-size planets with smaller orbital separations may not exist around A-type stars. I display that atmospheric photoevaporation due to high levels of near-ultraviolet radiation offers one possible explanation for this phenomenon. To test this hypothesis more robustly, I calculate the occurrence rate of small planets with orbital periods under 10 days around A-type stars. I demonstrate, for the first time, that sub-Saturns and sub-Neptunes are rarer around A-type stars than they are around their cooler counterparts. I also find evidence that super-Earths are as common or less common around A-type stars than cooler stars. These results suggest that small planets are unable to form at, migrate to, or survive at the small orbital separations probed by TESS around these hot stars. Overall, these findings significantly advance our understanding of how planets form and evolve around stars hotter than the Sun, providing a more holistic picture of planetary populations throughout the galaxy
Recommended from our members
Detecting and Characterizing Small Planets in Diverse Environments
No full textOur ability to detect and characterize small planets in diverse environments is expanding rapidly with the development and continued improvement of the transit and radial velocity methods. Better models, instruments, and telescopes are producing greater planet yields and tighter planetary radius and mass constraints, which in turn provide new targets for atmospheric characterization and produce new insights on planet composition, formation, and evolution. In this thesis, I present work on the characterization and mass determination of small planets with the radial velocity method, the detection of new planets via the transit method, and the study of a planet’s atmosphere through transmission spectroscopy and its implications for planet formation and planet population features.First, I report on mass estimation and characterization of the long-period exoplanet Kepler- 538b. This sub-Neptune with a period of P = 81.7 days is the only planet known to be orbiting its Sun-like star (0.892 M⊙). Simultaneously modeling Kepler photometry and radial velocities (RVs) yields a semi-amplitude of 1.68 ± 0.39 m s−1 and a planet mass of 10.6 ± 2.5 M⊕, which made Kepler-538b the smallest planet beyond P = 50 days with an RV mass measurement at the time of publication. Precise mass measurements on long-period planets will not only directly address questions about the long-period planet population, but also draw comparisons and shed light on aspects of the short-period planet population like the planetary radius occurrence gap and the impact of high stellar irradiation on exoplanet compositions and atmospheres.Next, I discuss K2-136c, a sub-Neptune with a period of P = 17.3 days and the largest of three transiting planets orbiting a late-K dwarf (0.742 M⊙) in the young Hyades open cluster (650 ± 70 Myr). Collecting and analyzing RV data from the HARPS-N and ESPRESSO spectrographs jointly with photometry from the K2 and TESS space telescopes yielded an RV semi-amplitude of 5.46 ± 0.45 m s−1 for K2-136c, corresponding to a mass of 18.0 ± 1.7 M⊕. K2-136c is now the smallest planet to have a measured mass in an open cluster and one of the youngest planets ever with a mass measurement. As a result, this system adds an important new window into young small planet compositions, atmospheric mass loss constraints around young active stars, and planetary evolution at relatively unexplored ages.I then present the TATER planet detection pipeline and apply it to high-cadence photometry of 914 known planet systems observed during TESS Cycle 3. This work has led to the new validation of 4 short-period planets. This study provides independent modeling and vetting of hundreds of planet candidates while also expanding the known planet population and providing updated transit ephemerides and planet radii.Finally, I report on the atmospheric characterization of WASP-166b, a short-period super- Neptune (P = 5.44 d, Mp = 32.1 ± 1.6 M⊕, Rp = 7.1 ± 0.3 R⊕). WASP-166b is located near the edge of the Hot Neptune Desert, a sparse region of exoplanet parameter space at high stellar irradiation and intermediate planet radii. Using transmission spectroscopy of WASP-166b (two transit observations with the James Webb Space Telescope), initial analyses show evidence of H2O and CO2; no evidence of SO2, NH3, or a cloud deck; constraints on planetary metallicity and the C/O ratio; and a plausible formation pathway that includes planetesimal accretion followed by core erosion or photoevaporation. This in turn points to mechanisms that can create substellar or stellar C/O ratios and superstellar metallicities, like photoevaporation and core erosion, as feasible components of the formation of the Hot Neptune Desert
An investigation on the framework of dressing virtual humans
No full textThis thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Realistic human models are widely used in variety of applications. Much research has been carried out on improving realism of virtual humans from various aspects, such as body shapes, hair, and facial expressions and so on. In most occasions, these virtual humans need to wear garments. However, it is time-consuming and tedious to dress a human model using current software packages [Maya2004]. Several methods for dressing virtual humans have been proposed recently [Bourguignon2001, Turquin2004, Turquin2007 and Wang2003B]. The method proposed by Bourguignon et al [Bourguignon2001] can only generate 3D garment contour instead of 3D surface. The method presented by Turquin et al. [Turquin2004, Turquin2007] could generate various kinds of garments from sketches but their garments followed the shape of the body and the side of a garment looked not convincing because of using simple linear interpolation. The method proposed by Wang et al. [Wang2003B] lacked interactivity from users, so users had very limited control on the garment shape.This thesis proposes a framework for dressing virtual humans to obtain convincing dressing results, which overcomes problems existing in previous papers mentioned above by using nonlinear interpolation, level set-based shape modification, feature constraints and so on. Human models used in this thesis are reconstructed from real human body data obtained using a body scanning system. Semantic information is then extracted from human models to assist in generation of 3 dimensional (3D) garments. The proposed framework allows users to dress virtual humans using garment patterns and sketches. The proposed dressing method is based on semantic virtual humans. A semantic human model is a human body with semantic information represented by certain of structure and body features. The semantic human body is reconstructed from body scanned data from a real human body. After segmenting the human model into six parts some key features are extracted. These key features are used as constraints for garment construction.Simple 3D garment patterns are generated using the techniques of sweep and offset. To dress a virtual human, users just choose a garment pattern, which is put on the human body at the default position with a default size automatically. Users are allowed to change simple parameters to specify some sizes of a garment by sketching the desired position on the human body.To enable users to dress virtual humans by their own design styles in an intuitive way, this thesis proposes an approach for garment generation from user-drawn sketches. Users can directly draw sketches around reconstructed human bodies and then generates 3D garments based on user-drawn strokes. Some techniques for generating 3D garments and dressing virtual humans are proposed. The specific focus of the research lies in generation of 3D geometric garments, garment shape modification, local shape modification, garment surface processing and decoration creation. A sketch-based interface has been developed allowing users to draw garment contour representing the front-view shape of a garment, and the system can generate a 3D geometric garment surface accordingly. To improve realism of a garment surface, this thesis presents three methods as follows. Firstly, the procedure of garment vertices generation takes key body features as constraints. Secondly, an optimisation algorithm is carried out after generation of garment vertices to optimise positions of garment vertices. Finally, some mesh processing schemes are applied to further process the garment surface. Then, an elaborate 3D geometric garment surface can be obtained through this series of processing. Finally, this thesis proposes some modification and editing methods. The user-drawn sketches are processed into spline curves, which allow users to modify the existing garment shape by dragging the control points into desired positions. This makes it easy for users to obtain a more satisfactory garment shape compared with the existing one. Three decoration tools including a 3D pen, a brush and an embroidery tool, are provided letting users decorate the garment surface by adding some small 3D details such as brand names, symbols and so on. The prototype of the framework is developed using Microsoft Visual Studio C++,OpenGL and GPU programming
The dressing method as non linear superposition in sigma models
No full textWe apply the dressing method on the Non Linear Sigma Model (NLSM), which describes the propagation of strings on ℝ × S2, for an arbitrary seed. We obtain a formal solution of the corresponding auxiliary system, which is expressed in terms of the solutions of the NLSM that have the same Pohlmeyer counterpart as the seed. Accordingly, we show that the dressing method can be applied without solving any differential equations. In this context a superposition principle emerges: the dressed solution is expressed as a non-linear superposition of the seed with solutions of the NLSM with the same Pohlmeyer counterpart as the seed. © 2021, The Author(s)
Survey of infection control in central venous catheters: Practice varies and is inconsistent with CDC Guidelines
No full textBackground: Intensive care patients with a central venous catheter are at risk of catheter-related infection, which increases morbidity, mortality and healthcare costs. Infection control practices, including care of the intravenous administration sets and catheter site, are undertaken by nurses in an attempt to avoid infection. Although practice guidelines are available, anecdotal reports suggest that infection control practices vary between practitioners and institutions; however, current practice has not been formally surveyed.\ud
\ud
Aim: To evaluate the current infection control practices for central venous catheter care and to compare these to evidence-based practice guidelines. \ud
\ud
Design: Prospective, cross-sectional descriptive survey.\ud
\ud
Method: Intensive care units (n=14) from Australia were surveyed about their infection control policies for central venous catheter care. Results were tabulated and compared with evidence-based practice guidelines (Guidelines for the Prevention of Intravascular Catheter-Related Infections, Centers for Disease Control [CDC], United States).\ud
\ud
Results: A wide variety of responses were received regarding duration of administration set use for standard, parenteral nutrition and propofol infusions; ad hoc administration set connection technique; dressing frequency, materials and solutions; and barrier precautions used during procedures. There was inconsistent adherence to the CDC Guidelines.\ud
\ud
Conclusions: There is currently great variation in the infection control approach to central venous catheter care. Greater adherence to existing CDC Guidelines would assist in the standardisation of best practice and facilitate evidence-based care
The Kepler-19 System: A Thick-envelope Super-Earth with Two Neptune-mass Companions Characterized Using Radial Velocities and Transit Timing Variations
No full textWe report a detailed characterization of the Kepler-19 system. This star was previously known to host a transiting planet with a period of 9.29 days, a radius of 2.2 R_⊕, and an upper limit on the mass of 20 M_⊕. The presence of a second, non-transiting planet was inferred from the transit time variations (TTVs) of Kepler-19b over eight quarters of Kepler photometry, although neither the mass nor period could be determined. By combining new TTVs measurements from all the Kepler quarters and 91 high-precision radial velocities obtained with the HARPS-N spectrograph, using dynamical simulations we obtained a mass of 8.4 ± 1.6 M ⊕ for Kepler-19b. From the same data, assuming system coplanarity, we determined an orbital period of 28.7 days and a mass of 13.1 ± 2.7 M_⊕ for Kepler-19c and discovered a Neptune-like planet with a mass of 20.3 ± 3.4 M_⊕ on a 63-day orbit. By comparing dynamical simulations with non-interacting Keplerian orbits, we concluded that neglecting interactions between planets may lead to systematic errors that can hamper the precision in the orbital parameters when the data set spans several years. With a density of 4.32 ± 0.87 g cm^(−3) (0.78 ± 0.16 ρ_⊕) Kepler-19b belongs to the group of planets with a rocky core and a significant fraction of volatiles, in opposition to low-density planets characterized only by transit time variations and an increasing number of rocky planets with Earth-like density. Kepler-19 joins the small number of systems that reconcile transit timing variation and radial velocity measurements
Recommended from our members
The Occurrence of Potentially Habitable Planets Orbiting M Dwarfs Estimated From the Full Kepler Dataset and an Empirical Measurement of the Detection Sensitivity
No full textWe present an improved estimate of the occurrence rate of small planets orbiting small stars by searching the full four-year Kepler data set for transiting planets using our own planet detection pipeline and conducting transit injection and recovery simulations to empirically measure the search completeness of our pipeline. We identified 156 planet candidates, including one object that was not previously identified as a Kepler Object of Interest. We inspected all publicly available follow-up images, observing notes, and centroid analyses, and corrected for the likelihood of false positives. We evaluated the sensitivity of our detection pipeline on a star-by-star basis by injecting 2000 transit signals into the light curve of each target star. For periods shorter than 50 days, we find 0.56+0.06 −0.05 Earthsize planets (1 − 1.5 R⊕) and 0.46+0.07 −0.05 super-Earths (1.5 − 2 R⊕) per M dwarf. In total, we estimate a cumulative planet occurrence rate of 2.5 ± 0.2 planets per M dwarf with radii 1 − 4 R⊕ and periods shorter than 200 days. Within a conservatively defined habitable zone based on the moist greenhouse inner limit and maximum greenhouse outer limit, we estimate an occurrence rate of 0.16+0.17 −0.07 Earthsize planets and 0.12+0.10 −0.05 super-Earths per M dwarf habitable zone. Adopting the broader insolation boundaries of the recent Venus and early Mars limits yields a higher estimate of 0.24+0.18−0.08 Earth-size planets and 0.21+0.11 −0.06 super-Earths per M dwarf habitable zone. This suggests that the nearest potentially habitable non-transiting and transiting Earth-size planets are 2.6 ± 0.4 pc and 10.6 +1.6 −1.8 pc away, respectively. If we include super-Earths, these distances diminish to 2.1±0.2 pc and 8.6 +0.7−0.8 pc.AstronomyAccepted Manuscrip
Fatty acid-based polyurethane films for wound dressing applications
No full textFatty acid-based polyurethane films were prepared for use as potential wound dressing material. The polymerization reaction was carried out with or without catalyst. Polymer films were prepared by casting-evaporation technique with or without crosslink-catalyst. The film prepared from uncatalyzed reaction product with crosslink-catalyst gave slightly higher crosslink density. The mechanical tests showed that, the increase in the tensile strength and decrease in the elongation at break is due to the increase in the degree of crosslinking. All films were flexible, and resisted to acid solution. The films prepared without crosslink-catalyst were more hydrophilic, absorbed more water. The highest permeability values were generally obtained for the films prepared without crosslink catalyst. Both the direct contact method and the MMT test were applied for determination of cytotoxicity of polymer films and the polyurethane film prepared from uncatalyzed reaction product without crosslink-catalyst showed better biocompatibility property, closest to the commercial product, Opsite®.DelftChemTechApplied Science
Non-operative management of fingertip injuries with an intravenous dressing
No full textObjective: The optimal management of fingertip injuries is a much debated topic. Surgical and nonsurgical options, including treatment with dressings alone, have comparable results. IV3000 is a semiocclusive dressing with a high reactive moisture vapour transmission rate (MVTR) compared to its alternatives. As the fingertip is crucial to hand function, determining the optimal dressing to treat these injuries is of clinical importance. The aim of this study is to collect preliminary data on the IV dressing when used to treat fingertip injuries. l Method: Patients were recruited from the department of orthopaedic surgery outpatient clinic. Inclusion criteria were a fingertip injury with skin loss and emergency department treatment consistent with the study protocol, including washing the fingertip, simple debridement as required, administration of antibiotics, tetanus prophylaxis, and fingertip dressed with the IV dressing. l Results: Fingertip injuries (15) from 13 male patients were identified. With the exception of one, all injuries were treated with the IV dressing and were included in the analysis. The treatment outcome of 13 injuries was rated as ‘satisfactory’ by the patients, while one was rated ‘indifferent’. The latter was on one of two patients with injuries to two digits. No patient reported their outcome as ‘unsatisfactory’. At the 18–24 months’ follow-up, seven of the 14 affected digits had some degree of hypersensitivity, eight regained normal pulp thicknesses, one had thickened padding, and five had reduced pulp volume. All but one patient reported some degree of numbness. Nail involvement was seen in 11 injuries, all of which continued to have some degree of nail deformity. l Conclusion: The IV dressing provides satisfactory outcomes when used to treat fingertip injuries. As the dressing possesses properties that suggest it would result in a superior healing environment compared to other semi-occlusive dressings, a prospective, randomised control trial should be conducted to determine whether these properties translate into superior outcomes when used to treat fingertip injuries. l Declaration of interest: All authors declare that they have no conflicts of interest to disclose. No author has any personal or professional interest in the product being investigated in this study.N.B. Ha, A.C. Chang, J.S. Sullivan, D.T. Leonell
- …
