Cloud feedback mechanisms and their representation in global climate models

Cloud feedback – the change in top-of-atmosphere radiative flux resulting from the cloud response to warming – constitutes by far the largest source of uncertainty in the climate response to CO2 forcing simulated by global climate models (GCMs). We review the main mechanisms for cloud feedbacks, and discuss their representation in climate models and the sources of inter-model spread. Global-mean cloud feedback in GCMs results from three main effects: (1) rising free- tropospheric clouds (a positive longwave effect); (2) decreasing tropical low cloud amount (a positive shortwave effect); (3) increasing high-latitude low cloud optical depth (a negative shortwave effect). These cloud responses simulated by GCMs are qualitatively supported by theory, high-resolution modeling, and observations. Rising high clouds are consistent with the Fixed Anvil Temperature (FAT) hypothesis, whereby enhanced upper-tropospheric radiative cooling causes anvil cloud tops to remain at a nearly fixed temperature as the atmosphere warms. Tropical low cloud amount decreases are driven by a delicate balance between the effects of vertical turbulent fluxes, radiative cooling, large-scale subsidence, and lower-tropospheric stability on the boundary-layer moisture budget. High-latitude low cloud optical depth increases are dominated by phase changes in mixed- phase clouds. The causes of inter-model spread in cloud feedback are discussed, focusing particularly on the role of unresolved parameterized processes such as cloud microphysics, turbulence, and convection

Resident Perception of Academic Skills Training and Impact on Academic Career Choice

Objectives: 1) To evaluate residents' perceptions of the quality of training in basic academic skills and the availability and quality of research resources during residency; 2) to evaluate the association between these attitudes and choice of an academic career; and 3) to assess residents' attitudes toward the importance of postgraduate fellowship training for success in an academic career. Methods: A 15-item survey was administered to all U.S. emergency medicine (EM) residents in conjunction with the February 1997 American Board of Emergency Medicine (ABEM) In-service Examination. The survey assessed resident interest in a career in academic EM, and resident perception of the general quality of training in academic (research and teaching) skills. Residents were also asked to rate the quality of their training in the following specific academic skills: medical and grant writing, bedside teaching, lecturing, the use of computers, study design, statistics, and the use of audiovisual aids. Resident perceptions of the availability of the following resources were also assessed: teaching and research role models, data collection and analysis support, laboratory facilities, financial support of research, research fundamentals lectures, and computers. Results: The response rate was 93%. Forty-four percent of the respondents were interested in academic EM, 36.6% were undecided, and 19.6% were not interested in an academic career. On a scale of 1 (unprepared) to 5 (well prepared), the residents rated their overall preparedness for an academic career fairly high (3.97 [0.86]). In contrast, they perceived the quality of their training in the specific academic skill areas assessed and research resource availability to be only fair. Despite resident perception of relatively inadequate training in basic academic skills, only 24% of the respondents indicated that they believed fellowship training was important for success in an academic career. Logistic regression analyses demonstrated that participation in a research project in medical school, the length of the training program (4- vs 3-year), being a first-year resident, and a better perception of one's overall academic skill preparation were factors independently associated with having a greater interest in an academic career. Conclusions: A relatively high percentage of residents initially express an interest in an academic career, but this interest wanes as residency progresses. A minority of residents believe that their training provides them with the specific skills needed to succeed in academics, or with adequate exposure to research resources or mentors. Emergency medicine may be able to increase the number of qualified academic faculty by recruiting medical students with prior research experience, and providing residents with better research training and role models.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72196/1/j.1553-2712.2000.tb00499.x.pd

A Systematic Review of Online Sex Addiction and Clinical Treatments Using CONSORT Evaluation

Researchers have suggested that the advances of the Internet over the past two decades have gradually eliminated traditional offline methods of obtaining sexual material. Additionally, research on cybersex and/or online sex addictions has increased alongside the development of online technology. The present study extended the findings from Griffiths’ (2012) systematic empirical review of online sex addiction by additionally investigating empirical studies that implemented and/or documented clinical treatments for online sex addiction in adults. A total of nine studies were identified and then each underwent a CONSORT evaluation. The main findings of the present review provide some evidence to suggest that some treatments (both psychological and/or pharmacological) provide positive outcomes among those experiencing difficulties with online sex addiction. Similar to Griffiths’ original review, this study recommends that further research is warranted to establish the efficacy of empirically driven treatments for online sex addiction

Accelerating global left-ventricular function assessment in mice using reduced slice acquisition and three-dimensional guide-point modelling

<p>Abstract</p> <p>Background</p> <p>To investigate the utility of three-dimensional guide-point modeling (GPM) to reduce the time required for CMR evaluation of global cardiac function in mice, by reducing the number of image slices required for accurate quantification of left-ventricular (LV) mass and volumes.</p> <p>Methods</p> <p>Five female C57Bl/6 mice 8 weeks post myocardial infarction induced by permanent occlusion of the left coronary artery, and six male control (un-operated) C57Bl/6 mice, were subject to CMR examination under isoflurane anaesthesia. Contiguous short axis (SAX) slices (1 mm thick 7-9 slices) were obtained together with two long axis (LAX) slices in two chamber and four chamber orientations. Using a mathematical model of the heart to interpolate information between the available slices, GPM LV mass and volumes were determined using full slice (all SAX and two LAX), six slice (four SAX and two LAX) and four slice (two SAX and two LAX) analysis protocols. All results were compared with standard manual volumetric analysis using all SAX slices.</p> <p>Results</p> <p>Infarct size was 39.1 ± 5.1% of LV myocardium. No significant differences were found in left ventricular mass and volumes between the standard and GPM full and six slice protocols in infarcted mice (113 ± 10, 116 ± 11, and 117 ± 11 mg respectively for mass), or between the standard and GPM full, six and four slice protocols in control mice, (105 ± 14, 106 ± 10, 104 ± 12, and 105 ± 7 mg respectively for mass). Significant differences were found in LV mass (135 ± 18 mg) and EF using the GPM four slice protocol in infarcted mice (p < 0.05).</p> <p>Conclusion</p> <p>GPM enables accurate analysis of LV function in mice with relatively large infarcts using a reduced six slice acquisition protocol, and in mice with normal/symmetrical left-ventricular topology using a four slice protocol.</p

Endometrial Cancer Presenting as Acute Urinary Retention: a Case Report and Review of the Literature

This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens

Endometrial Cancer Presenting as Acute Urinary Retention : a Case Report and Review of The Literature

This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens

The Linear Algebraic Method for Electron-Molecule Collisions

In order to find numerical solutions to many problems in physics, chemistry and engineering it is necessary to place the equations of motion (classical or quantal) of the variables of dynamical interest on a discrete mesh. The formulation of scattering theory in quantum mechanics is no exception and leads to partial differential or integral equations which may only be solved on digital computers. Typical approaches introduce a numerical grid or basis set expansion of the scattering wavefunction in order to reduce `the problem to the solution of a set of algebraic equations. Often it is more convenient to deal with the scattering matrix or phase amplitude rather than the wavefunction but the essential features of the numerics are unchanged. In this section we will formulate the Linear Algebraic Method (LAM) for electron-atom/molecule scattering for a simple, one-dimensional radial potential. This will illustrate the basic approach and enable the uninitiated reader to follow the subsequent discussion of the general, multi-channel, electron-molecule formulation without undue difficulty. We begin by writing the Schroedinger equation for the s-wave scattering of a structureless particle by a short-range, local potential

The effect of S-substitution at the O6-guanine site on the structure and dynamics of a DNA oligomer containing a G:T mismatch

The effect of S-substitution on the O6 guanine site of a 13-mer DNA duplex containing a G:T mismatch is studied using molecular dynamics. The structure, dynamic evolution and hydration of the S-substituted duplex are compared with those of a normal duplex, a duplex with Ssubstitution on guanine, but no mismatch and a duplex with just a G:T mismatch. The S-substituted mismatch leads to cell death rather than repair. One suggestion is that the G:T mismatch recognition protein recognises the S-substituted mismatch (GS:T) as G:T. This leads to a cycle of futile repair ending in DNA breakage and cell death. We find that some structural features of the helix are similar for the duplex with the G:T mismatch and that with the S-substituted mismatch, but differ from the normal duplex, notably the helical twist. These differences arise from the change in the hydrogen-bonding pattern of the base pair. However a marked feature of the S-substituted G:T mismatch duplex is a very large opening. This showed considerable variability. It is suggested that this enlarged opening would lend support to an alternative model of cell death in which the mismatch protein attaches to thioguanine and activates downstream damage-response pathways. Attack on the sulphur by reactive oxygen species, also leading to cell death, would also be aided by the large, variable opening