bluuebunny/crossref_metadata_2025 huggingface dataset:
Exploration of perceived effects of innovations in postgraduate medical education
Authors: Fokkema Joanne P I , Teunissen Pim W , Westerman Michiel , van der Lee Nadine , van der Vleuten Cees P M , Scherpbier Albert J J A , Dörr P Joep , Scheele Fedde
Published: February 2013

Context  Many studies have examined how educational innovations in postgraduate medical education (PGME) impact on teaching and learning, but little is known about effects in the clinical workplace outside the strictly education‐related domain. Insights into the full scope of effects may facilitate the implementation and acceptance of innovations because expectations can be made more realistic, and difficulties and pitfalls anticipated. Using workplace‐based assessment (WBA) as a reference case, this study aimed to determine which types of effect are perceived by users of innovations in PGME.

Methods  Focusing on WBA as a recent instance of innovation in PGME, we conducted semi‐structured interviews to explore perceptions of the effects of WBA in a purposive sample of Dutch trainees and (lead) consultants in surgical and non‐surgical specialties. Interviews conducted in 2011 with 17 participants were analysed thematically using template analysis. To support the exploration of effects outside the domain of education, the study design was informed by theory on the diffusion of innovations.

Results  Six domains of effects of WBA were identified: sentiments (affinity with the innovation and emotions); dealing with the innovation; specialty training; teaching and learning; workload and tasks, and patient care. Users’ affinity with WBA partly determined its effects on teaching and learning. Organisational support and the match between the innovation and routine practice were considered important to minimise additional workload and ensure that WBA was used for relevant rather than easily assessable training activities. Dealing with WBA stimulated attention for specialty training and placed specialty training on the agenda of clinical departments.

Conclusions  These outcomes are in line with theoretical notions regarding innovations in general and may be helpful in the implementation of other innovations in PGME. Given the substantial effects of innovations outside the strictly education‐related domain, individuals designing and implementing innovations should consider all potential effects, including those identified in this study.
Qualitative synthesis and systematic review in health professions education
Authors: Bearman Margaret , Dawson Phillip
Published: February 2013

Context  Formal qualitative synthesis is the process of pooling qualitative and mixed‐method research data, and then drawing conclusions regarding the collective meaning of the research. Qualitative synthesis is regularly used within systematic reviews in the health professions literature, although such use has been heavily debated in the general literature. This controversy arises in part from the inherent tensions found when generalisations are derived from in‐depth studies that are heavily context‐dependent.

Methods  We explore three representative qualitative synthesis methodologies: thematic analysis; meta‐ethnography, and realist synthesis. These can be understood across two dimensions: integrative to interpretative, and idealist to realist. Three examples are used to illustrate the relative strengths and limitations of these approaches.

Discussion  Against a backdrop of controversy and diverse methodologies, readers must take a critical stand when reading literature reviews that use qualitative synthesis to derive their findings. We argue that notions of qualitative rigour such as transparency and acknowledgment of the researchers’ stance should be applied to qualitative synthesis.
Workplace‐based assessments in Foundation Programme training: do trainees in difficulty use them differently?
Authors: Mitchell Colin , Bhat Sarita , Herbert Anne , Baker Paul
Published: February 2013

Context  Trainee‐led workplace‐based assessment (WPBA) is increasingly used in postgraduate medical training. Trainees in difficulty are known to behave differently from their peers; these differences may be reflected in their use of WPBAs and may give new insights into the behaviour and assessment of struggling trainees.

Methods  Data were extracted for 76 115 assessments, completed by 1900 UK Foundation Programme (FP) trainees. Of these 1900 trainees, 95 (5%) were FP trainees in difficulty (FTiDs). We analysed aspects of the use of WPBAs, using multiple logistic regressions, to compare the behaviours of FTiDs with those of their peers.

Results  Of 48 possible comparisons, only two (i.e. the rate expected to occur by chance) showed statistically significant differences: relative to their peers, FTiDs were more likely to choose nurse assessors in direct observations of procedural skills (odds ratio [OR] 7.05, 95% confidence interval [CI] 1.23–40.43) and more likely to choose non‐clinical assessors for assessments using the mini‐peer assessment tool (OR 30.44, 95% CI 1.34–689.29).

Conclusions  Key features of assessor choice for FTiDs are familiarity and likelihood of receiving a positive assessment. This analysis has not demonstrated that FTiDs use WPBAs any differently from their peers who are not in difficulty, although it does suggest associations and trends that require further exploration. These null results are interesting and raise hypotheses for prospective confirmation or disproof, and for further qualitative work investigating how struggling trainees use WPBAs in order to guide the future implementation of WPBAs in postgraduate training.
Implementing behaviour change for healthier lifestyles in obese children
Authors: Gately P. J. , Curtis C.
Published: February 2013

Obesity is a major public health issue, the scale and consequences of which suggest the need for comprehensive action. It would appear that there is an imbalance between the investment in primary prevention and in secondary prevention in the form of obesity treatment. It is possible that this imbalance has contributed to our lack of progress in treating obese children effectively and at scale. We propose that an obesity centre of excellence that focuses resources on practice‐based evidence on obesity treatment can contribute to progress in this field. Such a model would also provide the necessary capability to build a national scale solution. While limited, there is an evidence base that shows weight loss and weight loss maintenance and broader health and wellbeing outcomes can be achieved in children and young people. As part of the centre of excellence, a broad range of research aligned to key issues, which include poor awareness of weight issues, poor communication and marketing, greater understanding of the key ingredients of successful weight management (especially in different groups), improved methods to assess the impact of interventions and improved translation research to scale up services to meet the significant demand that exists, would all contribute to a more comprehensive solution to the issue of obesity.
Crucial information needs of ICU charge nurses in Finland and Greece
Authors: Lundgrén‐Laine Heljä , Kalafati Maria , Kontio Elina , Kauko Tommi , Salanterä Sanna
Published: February 2013

Aims

To describe crucial information needs of ICU charge nurses, and to compare these needs in two countries in Europe.

Background

ICU charge nurses are on the front line for ensuring that the activities of their units are running smoothly. They are accountable for making sure that the right tasks are performed under the right circumstances, with the right people, at the right time.

Design and participants

An online survey based on a previous observation study regarding the ad hoc decision‐making of ICU shift leaders. A total of 257 Finnish and 50 Greek ICU charge nurses participated in this study, from 17 Finnish and 16 Greece ICUs for adults.

Methods

Our survey incorporated 122 statements divided into six dimensions (patient admission, organization and management of work, allocation of staff, allocation of material, special treatments and patient discharge) with a rating scale from 0 to 10. Analysis involved descriptive statistics. Mann–Whitney U and Kruskal–Wallis tests were used to compare the answers of the two countries. Validity was verified with confirmatory factor analysis and the reliability was tested with Cronbach's α values.

Results

The most crucial information needs of ICU charge nurses concerned the overall organization and management of work. Both staff‐related and individual patient‐related information was needed. Information needs of Finnish and Greek charge nurses concerned similar kinds of situations in ICUs. However, there were some differences that might depend on the cultural differences between the countries.

Conclusions

Accurate and real‐time information is a prerequisite for ICU charge nurses' ad hoc decision‐making during daily care management. Identification of the most crucial information is needed when tools for information management are developed.

Relevance to clinical practice:

The results of this study indicated that a major portion of immediate information needs of ICU charge nurses are internationally common in similar settings.
Influence of sieving time on the efficiency and accuracy of grain‐size analysis of beach and dune sands
Authors: Román‐Sierra Jorge , Muñoz‐perez Juan j. , Navarro‐Pons Marina
Published: February 2013

Grain size is a fundamental property of sediments and is commonly used to describe sedimentary facies and classify sedimentary environments. Among the various conventional techniques utilized to determine grain‐size frequency distributions, sieving is the most widely applied procedure. The accuracy of such analyses is, among other factors, strongly dependent on the sieving time. However, despite a substantial amount of research in this field, optimal sieving times for different types of sediments have, to date, not been established. In this article, the influence of sieving time on grain‐size analyses of medium‐grained microtidal and mesotidal beach and dune sands has been determined. To assess the precision of important textural parameters, such as median grain size, sorting, skewness and kurtosis, an error analysis was carried out for different sieving times (2, 5, 10, 15 and 20 minutes). After calibrating the analytical and sampling methodologies, significant deviations were registered when sieving time was less than 10 minutes. However, such deviations were very small and grain‐size distributions remained almost identical for sieving times of 10 minutes and longer, relative errors being as low as 0% in some cases.
Self‐Protective Altruism
Authors: Hirschberger Gilad
Published: February 2013

Prosocial behavior accentuates the tension between two conflicting human motivations, self‐interest and belongingness. Responding to the needs of others may compromise self‐interest. Acting callously, however, may lead to social disproval. These antagonistic responses are existentially meaningful as belongingness and self‐esteem have been found to regulate death anxiety. In this paper I critically examine three possible hypotheses concerning the tension between egotism and prosociality from a terror management perspective. The first hypothesis, the carpe diem hypothesis, suggests that when death is salient egotistic self‐interest overrides other‐oriented responses. The second hypothesis, the norm salience hypothesis, suggests that when death is salient people will respond according to the momentarily accessible social norm. The third hypothesis, the self‐protective altruism hypothesis, argues that when the prosocial cause reminds people of their fragile, mortal nature people will turn away from helping when death is salient, but when the prosocial cause is benign death salience will increase prosocial responding.
Efficacy of combined antiviral therapy with lamivudine and tenofovir in a liver transplanted girl with de novo hepatitis B virus infection
Authors: Tufano M. , Liccardo D. , Riva S. , Candusso M. , Torre G. , Iorio R.
Published: February 2013

The management of de novo hepatitis B (HBV) infection in children after liver transplantation is not well defined. Because this infection may induce severe liver disease in the graft liver, an efficient antiviral therapy is desirable. Here, we describe the favorable viral outcome observed in a liver transplanted girl with de novo HBV infection following combination therapy with lamivudine and tenofovir.
Analytical Solutions of Heat Transfer and Film Thickness in Thin-Film Evaporation
Authors: Yan Chunji , Ma H. B.
Published: February 2013

A mathematical model predicting heat transfer and film thickness in thin-film region is developed herein. Utilizing dimensionless analysis, analytical solutions have been obtained for heat flux distribution, total heat transfer rate per unit length, location of the maximum heat flux and ratio of conduction thermal resistance to convection thermal resistance in the evaporating film region. These analytical solutions show that the maximum dimensionless heat flux is constant which is independent of the superheat. Maximum total heat transfer rate is determined for a given film region. The ratio of conduction thermal resistance to convection thermal resistance is a function of dimensionless film thickness. This work will lead to a better understanding of heat transfer and fluid flow occurring in the evaporating film region.
Heat Transfer Investigation of Air Flow in Microtubes—Part II: Scale and Axial Conduction Effects
Authors: Lin Ting-Yu , Kandlikar Satish G.
Published: February 2013

In this paper, the scale effects are specifically addressed by conducting experiments with air flow in different microtubes. Three stainless steel tubes of 962, 308, and 83 μm inner diameter (ID) are investigated for friction factor, and the first two are investigated for heat transfer. Viscous heating effects are studied in the laminar as well as turbulent flow regimes by varying the air flow rate. The axial conduction effects in microtubes are experimentally explored for the first time by comparing the heat transfer in SS304 tube with a 910 μm ID/2005 μm outer diameter nickel tube specifically fabricated using an electrodeposition technique. After carefully accounting for the variable heat losses along the tube length, it is seen that the viscous heating and the axial conduction effects become more important at microscale and the present models are able to predict these effects accurately. It is concluded that neglecting these effects is the main source of discrepancies in the data reported in the earlier literature.
Role of Thermal-Interaction Between Aggregated Particles in Thermal Conductivity Enhancement of Nanofluids
Authors: Jin Jae Sik , Lee Joon Sik
Published: February 2013

This study investigates the role of thermal-interaction (TI) between aggregated particles (APs) on the enhanced thermal conductivity of nanofluids. With the assumption of configurations of linear chain-like aggregates in the direction transverse to the thermal flux, two-dimensional heat conduction is considered for estimation of the effective thermal conductivity of regular arrays, which is separated into three components, namely, no thermal-interaction (NTI) effect, longitudinal thermal-interaction (LTI) effect, and transverse thermal-interaction (TTI) effect. We have obtained a solution to the 1D confine case of APs, and a thermal analysis is carried out for different confine systems to investigate their relatively quantitative assessments of thermal contribution to the enhanced effective thermal conductivity using the first-order approximation. We show that these effects are represented as a function of ϕ (where ϕ is the volume fraction of APs) for engineering purposes. It is also found that TI contribution to the enhanced thermal conduction reaches up to around 87.5% when APs contact with each other and that TTI has an important role in the range 0.3785 ≤ ϕ ≤ 0.7031 due to the confine effect of field-variation caused by transversely bidirectional thermal-interactions. When ϕ > 0.7031, LTI effect again plays key role in heat conduction in nanofluid systems owing to closed packing of APs. Consequently, to achieve energy-efficient heat transfer nanofluids that are required in many industrial applications, both APs' distribution configuration and APs' volume fraction have to be considered in the thermal analysis of nanofluids.
A New Surgical Device for Minimally Invasive “Core-Out” Excision of High Fistula-in-Ano
Authors: Esmaeili Meysam , Najarian Siamak , Kashani Mohsen T.
Published: February 2013

Core fistulectomy with endorectal advancement flap repair has been reported as a safe and effective technique for treatment of high fistula-in-ano. A number of rigid and flexible fistulectomy sets have already been fabricated pursuing the objectives of facilitating the procedure of this conservative surgical technique and reducing its risks of continence impairment. Two different methods (the method of scraping the granulation tissue of fistula and the method of separating and removing a thin layer from inside of tract) have been served in these sets for obliterating the abnormalities. In this work, with the aim of minimizing invasion to healthy tissue encircling the fistula, specially sphincter muscles, we designed and fabricated a new flexible fistulectomy device, which uses the second mentioned method. The new set separates an approximately 2.5-mm-thick layer from inside of the fistulous tract, by rotating a special tubular blade around its axis and moving the blade along the fistulous tract from external orifice toward the internal orifice. At the same time, the separated tissue may be removed from the fistulectomy lumen by rotating a special cannulated screw embedded coaxially inside the tubular blade. A flexible guidewire was used for identifying the tract path and guiding the device along it. We used the new set for excising 10 curved fistula models of approximately 16 cm length and 1.5 mm diameter, which were created in cubic pieces of fresh cow muscle as test specimens. After removing the device, each specimen was left with a smooth-walled lumen of approximately 9 mm diameter. The tubular blade works very well in separating a thin layer from inside of the fistula models and the cannulated screw is capable of easily removing the separated tissue. The removed tissue could be used as a sample of the whole tract for histopathological examinations. The screw and flexible guidewire lead the blade along the tract in a good manner and ensure circumferential separation of the fistula. With regard to the results of our tests, it is anticipated that the new set is an efficient instrument for easy, safe and fast core-out excision of high anal fistulas and is able to reduce the risk of injuries to healthy tissue encircling the fistulous tract.
High Sensitive Force Sensing Based on the Optical Fiber Coupling Loss
Authors: Ahmadi Roozbeh , Packirisamy Muthukumaran , Dargahi Javad
Published: February 2013

In the present paper, an innovative miniaturized optical force sensor is introduced for use in medical devices such as minimally invasive robotic-surgery instruments. The sensing principle of the sensor relies on light transmission in optical fibers. Although the sensor is designed for use in surgical systems, it can be used in various other applications due to its novel features. The novelty of the sensor lies in offering four features in a single miniaturized package using a simple optical-based sensing principle. These four features are the high accuracy/resolution, the magnetic resonance compatibility, the electrical passivity, and the absence of drift in the measurement of continuous static force. The proposed sensor was micromachined using microsystems technology and tested. The sensor measures 18 mm, 4 mm, and 1 mm in length, width, and thickness, respectively. The sensor was calibrated and its performance under both static and dynamic loading conditions was investigated. The experimental test results demonstrate a 0.00–2.00 N force range with an rms error of approximately 2% of the force range. Its resolution is 0.02 N. The characteristics of the sensor such as its size, its measurement range, and its sensitivity are also easily tunable.
Material Handling System for Robotic Natural Orifice Surgery
Authors: Midday Jeff , Nelson Carl A. , Goyzueta Alan , Oleynikov Dmitry
Published: February 2013

Natural orifice translumenal endoscopic surgery (NOTES) is a relatively new surgical approach that uses no external incisions, thereby improving cosmetic outcomes, decreasing overall recovery time, and reducing the risk of external infection. In standard NOTES, flexible endoscopic tools have been used to carry out a variety of surgical procedures in the abdomen. As an alternative, miniature in vivo robots can be fully inserted into the peritoneal cavity and utilized to perform various surgical procedures. These in vivo robots eliminate tool triangulation issues, improve multitasking capabilities, and greatly increase freedom and dexterity when compared to standard endoscopic and laparoscopic tools. One major limitation is that once inserted, the in vivo robots are isolated within the abdomen and cannot send or receive materials to the external environment. The topic of this paper is a material handling system that has been developed to bridge this deficiency. This system features a flexible silicone overtube and an open-loop control system with manual and automatic operation capabilities. The system utilizes the helix of a spring to advance a payload (staples, robotic tool tips, etc.) along the length of the overtube. The system functioned as intended in benchtop and in vivo testing. Minimum bend radius was identified, and a payload was successfully advanced and retrieved through the shuttling system in porcine surgical procedures. NOTES access was achieved via a custom built transvaginal trocar. This paper presents the design and rationale, control strategy, and in vivo testing results for the NOTES material handling system. The system performs as intended based on functional requirements as demonstrated in benchtop and porcine in vivo testing. The control method is robust even when pushed beyond the physical constraints of the system. Collectively, the material handling system provides a simple, repeatable way for an operator to interface with miniature in vivo robots, improving surgical system flexibility while minimizing impact on the duration of an abdominal surgical procedure.
A Numerical Study of Atmospheric and Wake Turbulence Impacts on Wind Turbine Fatigue Loadings
Authors: Lee S. , Churchfield M. J. , Moriarty P. J. , Jonkman J. , Michalakes J.
Published: February 2013

Large-eddy simulations of atmospheric boundary layers under various stability and surface roughness conditions are performed to investigate the turbulence impact on wind turbines. In particular, the aeroelastic responses of the turbines are studied to characterize the fatigue loading of the turbulence present in the boundary layer and in the wake of the turbines. Two utility-scale 5 MW turbines that are separated by seven rotor diameters are placed in a 3 km by 3 km by 1 km domain. They are subjected to atmospheric turbulent boundary layer flow and data are collected on the structural response of the turbine components. The surface roughness was found to increase the fatigue loads while the atmospheric instability had a small influence. Furthermore, the downstream turbines yielded higher fatigue loads indicating that the turbulent wakes generated from the upstream turbines have significant impact.
Development and Evaluation of Drug Eluting Stent Having Biphasic Release From a Single Layer of Biodegradable Polymer
Authors: Thakkar Ashok , Raval Ankur , Mandal Ramila , Parmar Sanjay , Jariwala Arpit , Tailor Jaynish , Mehta Anita
Published: February 2013

In stent restenosis is the major disadvantage of percutaneous transluminal angioplasty. To overcome this limitation, drug eluting stents were introduced. We have developed novel sirolimus eluting stent using biocompatible and biodegradable polymer matrix. Developed stent have biphasic release profile for sirolimus from a single layer of polymer matrix, having blend of slow and fast degrading polymers. Coating integrity of coated stents were evaluated after crimping and postexpansion with the help of scanning electron microscopy while thickness of coated stent was measured using destructive test method. This shows that drug-polymers bilayer was uniformly coated with the average thickness of 5.2 μms. There was no deformation after crimping and expansion of the stent. We have also measured in vitro and in vivo release profiles of sirolimus from stents which shows biphasic release characteristics, i.e., initial burst period followed by sustained release. In vitro release profile is well correlated with in vivo release in blood and arterial tissues. Developed stents showed good efficacy and safety in porcine coronary artery model.
Capped carbon hard mask and trimming process: A low-cost and efficient route to nanoscale devices
Authors: Pauliac-Vaujour Sébastien , Brianceau Pierre , Comboroure Corinne , Faynot Olivier
Published: February 2013

Both sub-22 nm architecture design optimization and reliable, low-cost process development represent major challenges toward nanoscale device fabrication. In order to address the second of these two issues, the authors have demonstrated that it is possible to overcome current tool and process lithography limitations using a capped carbon hard mask process, without dramatically increasing device fabrication costs, as only existing tools are used in this process. Starting from 50 nm patterns, 25 nm fully depleted silicon-on-insulator (FDSOI) transistors with good reliability and acceptable electrical behavior are obtained. This patterning solution may be applied to existing lithography processes (dry or immersion ArF lithography) in order to enhance current resolution capabilities. Moreover, the use of a capping layer enables to set free from photoresist thickness limitations, which are becoming increasingly critical for sub-22 nm feature patterning. Indeed, for such dimensions, photoresist thickness generally needs to be lower than 66 nm in order to avoid pattern collapse effects. This trend can lead to serious integration problems especially for the fabrication of thick stack device architectures. Therefore, in addition to improving current lithography processes, our strategy may also be useful for novel lithography processes such as extreme ultraviolet lithography or maskless lithography. The authors have also demonstrated that the capped carbon hard mask process could enable the patterning of sub-11 nm FDSOI gates, with a current best result close to 7 nm, starting from 30 nm photoresist patterns. Note that all etching steps of the process have been performed in the same etching chamber, which is a key point for meeting industrial requirements. These results show that it is possible to bypass tool and process lithography limitations to pattern sub-22 nm devices without dramatically increasing fabrication costs while maintaining lithography throughput. The authors have therefore shown that the capped carbon hard mask process could be a high-performance and low-cost industry-compatible solution for nanoscale device fabrication.
Improving best‐phase image quality in cardiac CT by motion correction with MAM optimization
Authors: Rohkohl Christopher , Bruder Herbert , Stierstorfer Karl , Flohr Thomas
Published: February 2013

Purpose:

Research in image reconstruction for cardiac CT aims at using motion correction algorithms to improve the image quality of the coronary arteries. The key to those algorithms is motion estimation, which is currently based on 3‐D/3‐D registration to align the structures of interest in images acquired in multiple heart phases. The need for an extended scan data range covering several heart phases is critical in terms of radiation dose to the patient and limits the clinical potential of the method. Furthermore, literature reports only slight quality improvements of the motion corrected images when compared to the most quiet phase (best‐phase) that was actually used for motion estimation. In this paper a motion estimation algorithm is proposed which does not require an extended scan range but works with a short scan data interval, and which markedly improves the best‐phase image quality.

Methods:

Motion estimation is based on the definition of motion artifact metrics (MAM) to quantify motion artifacts in a 3‐D reconstructed image volume. The authors use two different MAMs, entropy, and positivity. By adjusting the motion field parameters, the MAM of the resulting motion‐compensated reconstruction is optimized using a gradient descent procedure. In this way motion artifacts are minimized. For a fast and practical implementation, only analytical methods are used for motion estimation and compensation. Both the MAM‐optimization and a 3‐D/3‐D registration‐based motion estimation algorithm were investigated by means of a computer‐simulated vessel with a cardiac motion profile. Image quality was evaluated using normalized cross‐correlation (NCC) with the ground truth template and root‐mean‐square deviation (RMSD). Four coronary CT angiography patient cases were reconstructed to evaluate the clinical performance of the proposed method.

Results:

For the MAM‐approach, the best‐phase image quality could be improved for all investigated heart phases, with a maximum improvement of the NCC value by 100% and of the RMSD value by 81%. The corresponding maximum improvements for the registration‐based approach were 20% and 40%. In phases with very rapid motion the registration‐based algorithm obtained better image quality, while the image quality of the MAM algorithm was superior in phases with less motion. The image quality improvement of the MAM optimization was visually confirmed for the different clinical cases.

Conclusions:

The proposed method allows a software‐based best‐phase image quality improvement in coronary CT angiography. A short scan data interval at the target heart phase is sufficient, no additional scan data in other cardiac phases are required. The algorithm is therefore directly applicable to any standard cardiac CT acquisition protocol.
Analytical derivation of the b matrix of a time‐efficient isotropic diffusion weighting gradient waveform
Authors: Trampel Robert , Johnson Glyn
Published: February 2013

Purpose:

Diffusion‐weighted magnetic resonance imaging of3He provides information about lung structure. If rotationally invariant measures of diffusion are desired, an equal diffusion weighting in all three spatial directions is necessary to obtain. In order to achieve such isotropic diffusion weighting, gradients have to be applied in these three spatial directions, which can be time consuming. Therefore, the purpose of this study was the analytic derivation of a time‐efficient isotropic diffusion weighting scheme.

Methods:

The completeb matrix of a preselected gradient waveform was derived analytically. The effect of ramp times and the contribution of the imaging gradients were included in the calculation. The time‐efficient waveform was compared to a standard isotropic diffusion weighting scheme by determining the mean diffusivity of hyperpolarized 3He in human lungs.

Results:

An analytically derived expression of theb matrix for a time‐efficient gradient scheme allowing isotropic diffusion weighting was derived. Additionally, the b matrix of a common set of imaging gradients was calculated. Diffusion measurements of hyperpolarized 3He in human lungs using the derived optimized gradient scheme and a standard gradient waveform used for isotropic diffusion weighting, respectively, gave results for the mean diffusivity which did not show any statistical difference. However, the echo time using the optimized scheme was reduced by 2.5 ms in comparison with the standard scheme which leads to a theoretical signal increase of 30%.

Conclusions:

The analytically derivedb matrix allows for the straightforward determination of time‐efficient isotropic diffusion weighting schemes. By using those schemes, a substantial gain in signal can be achieved whereas the resulting values for the mean diffusivity did not show any statistical difference to the values obtained when using standard waveforms for isotropic diffusion weighting.
Dark Matter
Authors: Lincoln Don
Published: February 2013

It's a dark, dark universe out there, and I don't mean because the night sky is black. After all, once you leave the shadow of the Earth and get out into space, you're surrounded by countless lights glittering everywhere you look. But for all of Sagan's billions and billions of stars and galaxies, it's a jaw-dropping fact that the ordinary kind of matter like that which makes up you and me is but 5% of the energy budget of the universe. The glittering spectacle of the heavens is a rather thin icing on a very large and dark cake.
Mechanical Parametric Oscillations and Waves
Authors: Dittrich William , Minkin Leonid , Shapovalov Alexander S.
Published: February 2013

Usually parametric oscillations are not the topic of general physics courses. Probably it is because the mathematical theory of this phenomenon is relatively complicated, and until quite recently laboratory experiments for students were difficult to implement.1 However parametric oscillations are good illustrations of the laws of physics and can be explained qualitatively; by using PASCO equipment,2 quantitative laboratory experiments can be designed rather easily. Below the following experiments are described: parametric oscillations of a simple pendulum, a vertical spring-mass system, and a stretched string.
Ten Things You Should Do with a Tuning Fork
Authors: Lincoln James
Published: February 2013

Tuning forks are wonderful tools for teaching physics. Every physics classroom should have several and every physics student should be taught how to use them. In this article, I highlight 10 enriching demonstrations that most teachers might not know, as well as provide tips to enhance the demonstrations teachers might already be doing. Some of these demonstrations have appeared in literature before, but this paper will serve as a collection of ideas that will be helpful for both the beginner and master teacher.
Metamaterials with Quantum Gain
Authors: Hess Ortwin , Tsakmakidis Kosmas L.
Published: February 2013

Integrating amplifying media with metamaterials allows loss-free plasmonic operation and opens a route for controlling nanoscale quantum emitters.
Development and Optimization of a Novel Assay To Measure Neutralizing Antibodies against Clostridium difficile Toxins
Authors: Xie Jinfu , Zorman Julie , Indrawati Lani , Horton Melanie , Soring Keri , Antonello Joseph M. , Zhang Yuhua , Secore Susan , Miezeiewski Matthew , Wang Su , Kanavage Anthony D. , Skinner Julie M. , Rogers Irene , Bodmer Jean-Luc , Heinrichs Jon H.
Published: February 2013

Clostridium difficile
produces two major virulence toxins, toxin A (TcdA) and toxin B (TcdB). Antitoxin antibodies, especially neutralizing antibodies, have been shown to be associated with a lower incidence of
C. difficile
infection (CDI) recurrence, and antibody levels are predictive of asymptomatic colonization. The development of an assay to detect the presence of neutralizing antibodies in animal and human sera for the evaluation of vaccine efficacy is highly desired. We have developed such an assay, which allows for the quantification of the effect of toxins on eukaryotic cells in an automated manner. We describe here the optimization of this assay to measure toxin potency as well as neutralizing antibody (NAb) activity against
C. difficile
toxins using a design-of-experiment (DOE) methodology. Toxin concentration and source, cell seeding density, and serum-toxin preincubation time were optimized in the assay using Vero cells. The assay was shown to be robust and to produce linear results across a range of antibody concentrations. It can be used to quantify neutralizing antibodies in sera of monkeys and hamsters immunized with
C. difficile
toxoid vaccines. This assay was shown to correlate strongly with traditional assays which rely on labor-intensive methods of determining neutralizing antibody titers by visual microscopic inspection of intoxicated-cell monolayers. This assay has utility for the selection and optimization of
C. difficile
vaccine candidates.
Modified Hodge Test versus Indirect Carbapenemase Test: Prospective Evaluation of a Phenotypic Assay for Detection of Klebsiella pneumoniae Carbapenemase (KPC) in Enterobacteriaceae
Authors: Mathers Amy J. , Carroll Joanne , Sifri Costi D. , Hazen Kevin C.
Published: February 2013

The currently recommended phenotypic test for the detection of carbapenemase-producing members of the family
Enterobacteriaceae
is the modified Hodge test (MHT). However, the MHT lacks specificity. Here we demonstrate an alternative phenotypic test, the indirect carbapenemase test, for the detection of
bla
KPC
-producing isolates that has specificity superior to that of the MHT for non-
Klebsiella Enterobacteriaceae
.
The Repression Domain of the E1B 55-Kilodalton Protein Participates in Countering Interferon-Induced Inhibition of Adenovirus Replication
Authors: Chahal Jasdave S. , Gallagher Courtney , DeHart Caroline J. , Flint S. J.
Published: February 2013

To begin to investigate the mechanism by which the human adenovirus type 5 E1B 55-kDa protein protects against the antiviral effects of type 1 interferon (IFN) (J. S. Chahal, J. Qi, and S. J. Flint, PLoS Pathog.8:e1002853, 2012 [doi:10.1371/journal.ppat.1002853]), we examined the effects of precise amino acid substitution in this protein on resistance of viral replication to the cytokine. Only substitution of residues 443 to 448 of E1B for alanine (E1B Sub19) specifically impaired production of progeny virus and resulted in a large defect in viral DNA synthesis in IFN-treated normal human fibroblasts. Untreated or IFN-treated cells infected by this mutant virus (AdEasyE1Sub19) contained much higher steady-state concentrations of IFN-inducible GBP1 and IFIT2 mRNAs than did wild-type-infected cells and of the corresponding newly transcribed pre-mRNAs, isolated exploiting 5′-ethynyluridine labeling and click chemistry. These results indicated that the mutations created by substitution of residues 443 to 448 for alanine (Sub19) impair repression of transcription of IFN-inducible genes, by the E1B, 55-kDa protein, consistent with their location in a segment required for repression of p53-dependent transcription. However, when synthesized alone, the E1B 55-kDa protein inhibited expression of the p53-regulated genes BAX and MDM2 but had no impact whatsoever on induction of IFIT2 and GBP1 expression by IFN. These observations correlate repression of transcription of IFN-inducible genes by the E1B 55-kDa protein with protection against inhibition of viral genome replication and indicate that the E1B 55-kDa protein is not sufficient to establish such transcriptional repression.
Understanding public drug procurement in India: a comparative qualitative study of five Indian states
Authors: Singh Prabal Vikram , Tatambhotla Anand , Kalvakuntla Rohini , Chokshi Maulik
Published: February 2013

Objective

To perform an initial qualitative comparison of the different procurement models in India to frame questions for future research in this area; to capture the finer differences between the state models through 53 process and price parameters to determine their functional efficiencies.

Design

Qualitative analysis is performed for the study. Five states: Tamil Nadu, Kerala, Odisha, Punjab and Maharashtra were chosen to ensure heterogeneity in a number of factors such as procurement type (centralised, decentralised or mixed); autonomy of the procurement organisation; state of public health infrastructure; geography and availability of data through Right to Information Act (RTI). Data on procurement processes were collected through key informant analysis by way of semistructured interviews with leadership teams of procuring organisations. These process data were validated through interviews with field staff (stakeholders of district hospitals, taluk hospitals, community health centres and primary health centres) in each state. A total of 30 actors were interviewed in all five states. The data collected are analysed against 52 process and price parameters to determine the functional efficiency of the model.

Results

The analysis indicated that autonomous procurement organisations were more efficient in relation to payments to suppliers, had relatively lower drug procurement prices and managed their inventory more scientifically.

Conclusions

The authors highlight critical success factors that significantly influence the outcome of any procurement model. In a way, this study raises more questions and seeks the need for further research in this arena to aid policy makers.
THE ENTROPY OF A DIELECTRIC BLACK HOLE
Authors: ZHANG LICHUN , LI HUAIFAN , ZHAO REN , CAI RONGGEN
Published: February 2013

In a dielectric black hole background, photons will be radiated via Hawking evaporation mechanism. In this paper, we calculate the entanglement entropy associated with a static dielectric black hole by employing 't Hooft's brick-wall model. It is found that the lowest energy of radiated particles is coordinate dependent. The resulted entanglement entropy is composed of three parts: a parameter independent leading constant term [Formula: see text], a logarithmic correction term and some series terms. The convergency of the series terms is also discussed.
THERMOELECTRIC TRANSPORT PROPERTIES IN TRILAYER GRAPHENE SYSTEMS
Authors: MA RONG
Published: February 2013

We numerically study the thermoelectric transport properties in trilayer graphene in the presence of a strong perpendicular magnetic field and disorder. In the unbiased case, we find that the thermoelectric transport has similar properties as in monolayer graphene. In the high temperature regime, the transverse thermoelectric conductivity αxy saturates to a universal value 8.31 kBe/h at the center of each Landau level (LL), and displays a linear temperature dependence at low temperatures. The Nernst signal has a peak at the central LL with a height of the order of kB/e, while the thermopower changes sign. We attribute this to the coexistence of particle and hole LLs around the Dirac point. When a finite interlayer bias is applied and a band gap is opened, it is found that the transport properties are consistent with those of a band insulator.
THE GAUGE TRANSFORMATION OF THE CONSTRAINED SEMI-DISCRETE KP HIERARCHY
Authors: LI MAOHUA , CHENG JIPENG , HE JINGSONG
Published: February 2013

In this paper, the gauge transformation of the constrained semi-discrete KP(cdKP) hierarchy is constructed explicitly by the suitable choice of the generating functions. Under the m-step successive gauge transformation Tm, we give the transformed (adjoint) eigenfunctions and the τ-function of the transformed Lax operator of the cdKP hierarchy.
ALPHA ACCOMPANIED TERNARY FISSION OF SUPERHEAVY NUCLEI
Authors: THAKUR SHAGUN , KUMAR RAJESH , VIJAYARAGHAVAN K. R. , BALASUBRAMANIAM M.
Published: February 2013

Potential energy surfaces corresponding to the alpha accompanied ternary fragmentation in superheavy mass region have been investigated. The lowest value of potential energy is found for the configuration having alpha particle in between other two fragments. The position of deepest valleys in the potential energy surface indicates the most probable tri-partition of a given nucleus. The isotopic effect on the variation of the deepest valley has also been investigated. For the isotopic chain of Z = 114, the minimum is found at 140 Ce + 4 He + 136 Xe , suggesting this to be the most probable tri-partition. Similar possible configurations have been studied for Z = 116, 118 and 120 and the presence of proton/neutron magic number has been found in all the most probable combinations for alpha accompanied ternary fission.
Identification of prolyl carboxypeptidase as an alternative enzyme for processing of renal angiotensin II using mass spectrometry
Authors: Grobe Nadja , Weir Nathan M. , Leiva Orly , Ong Frank S. , Bernstein Kenneth E. , Schmaier Alvin H. , Morris Mariana , Elased Khalid M.
Published: February 2013

Angiotensin-converting enzyme 2 (ACE2) catalyzes conversion of ANG II to ANG-(1–7). The present study uses newly established proteomic approaches and genetic mouse models to examine the contribution of alternative renal peptidases to ACE2-independent formation of ANG-(1–7). In situ and in vitro mass spectrometric characterization showed that substrate concentration and pH control renal ANG II processing. At pH ≥6, ANG-(1–7) formation was significantly reduced in ACE2 knockout (KO) mice. However, at pH <6, formation of ANG-(1–7) in ACE2 KO mice was similar to that in wild-type (WT) mice, suggesting alternative peptidases for renal ANG II processing. Furthermore, the dual prolyl carboxypeptidase (PCP)-prolyl endopeptidase (PEP) inhibitor Z-prolyl-prolinal reduced ANG-(1–7) formation in ACE2 KO mice, while the ACE2 inhibitor MLN-4760 had no effect. Unlike the ACE2 KO mice, ANG-(1–7) formation from ANG II in PEP KO mice was not different from that in WT mice at any tested pH. However, at pH 5, this reaction was significantly reduced in kidneys and urine of PCP-depleted mice. In conclusion, results suggest that ACE2 metabolizes ANG II in the kidney at neutral and basic pH, while PCP catalyzes the same reaction at acidic pH. This is the first report demonstrating that renal ANG-(1–7) formation from ANG II is independent of ACE2. Elucidation of ACE2-independent ANG-(1–7) production pathways may have clinically important implications in patients with metabolic and renal disease.
Serotonin and cholecystokinin mediate nutrient-induced segmentation in guinea pig small intestine
Authors: Ellis Melina , Chambers Jordan D. , Gwynne Rachel M. , Bornstein Joel C.
Published: February 2013

Segmentation is an important process in nutrient mixing and absorption; however, the mechanisms underlying this motility pattern are poorly understood. Segmentation can be induced by luminal perfusion of fatty acid in guinea pig small intestine in vitro and mimicked by the serotonin (5-HT) reuptake inhibitor fluoxetine (300 nM) and by cholecystokinin (CCK). Serotonergic and CCK-related mechanisms underlying nutrient-induced segmentation were investigated using selective 5-HT and CCK receptor antagonists on isolated segments of small intestine luminally perfused with 1 mM decanoic acid. Motility patterns were analyzed using video imaging and spatiotemporal maps. Segmenting activity mediated by decanoic acid was depressed following luminal application of the 5-HT receptor antagonists granisetron (5-HT3, 1 μM) and SB-207266 (5-HT4, 10 nM) and the CCK receptor antagonists devazepide (CCK-1, 300 nM) and L-365260 (CCK-2, 300 nM), but these antagonists did not further depress segmentation when combined. The P2 receptor antagonist pyridoxal phosphate-6-azophenyl-2′,4′-disulfonate (10 μM) had no effect on activity. Serosal application of 5-HT antagonists had little effect on segmentation in the duodenum but reduced activity in the jejunum when granisetron and SB-207266 were applied together. These results reveal that 5-HT3and 5-HT4receptors, as well as CCK-1 and CCK-2 receptors, are critical in regulating decanoic acid-induced segmentation. Computational simulation indicated that these data are consistent with decanoic acid activating two pathways in the mucosa that converge within the enteric neural circuitry, while contraction-induced release of 5-HT from the mucosa provides feedback into the neural circuit to set the time course of the overall contractile activity.