Nonequilibrium gating and voltage dependence of the ClC-0 Cl- channel.

The gating of ClC-0, the voltage-dependent Cl- channel from Torpedo electric organ, is strongly influenced by Cl- ions in the external solution. Raising external Cl- over the range 1-600 mM favors the fast-gating open state and disfavors the slow-gating inactivated state. Analysis of purified single ClC-0 channels reconstituted into planar lipid bilayers was used to identify the role of Cl- ions in the channel's fast voltage-dependent gating process. External, but not internal, Cl- had a major effect on the channel's opening rate constant. The closing rate was more sensitive to internal Cl- than to external Cl-. Both opening and closing rates varied with voltage. A model was derived that postulates (a) that in the channel's closed state, Cl- is accessible to a site located at the outer end of the conduction pore, where it binds in a voltage-independent fashion, (b) that this closed conformation can open, whether liganded by Cl- or not, in a weakly voltage-dependent fashion, (c) that the Cl(-)-liganded closed channel undergoes a conformational change to a different closed state, such that concomitant with this change, Cl- ion moves inward, conferring voltage-dependence to this step, and (d) that this new Cl(-)-liganded closed state opens with a very high rate. According to this picture, Cl- movement within the pre-open channel is the major source of voltage dependence, and charge movement intrinsic to the channel protein contributes very little to voltage-dependent gating of ClC-0. Moreover, since the Cl- activation site is probably located in the ion conduction pathway, the fast gating of ClC-0 is necessarily coupled to ion conduction, a nonequilibrium process

Ambient connections realising conformal Tractor holonomy

For a conformal manifold we introduce the notion of an ambient connection, an affine connection on an ambient manifold of the conformal manifold, possibly with torsion, and with conditions relating it to the conformal structure. The purpose of this construction is to realise the normal conformal tractor holonomy as affine holonomy of such a connection. We give an example of an ambient connection for which this is the case, and which is torsion free if we start the construction with a C-space, and in addition Ricci-flat if we start with an Einstein manifold. Thus for a $C$-space this example leads to an ambient metric in the weaker sense of \v{C}ap and Gover, and for an Einstein space to a Ricci-flat ambient metric in the sense of Fefferman and Graham.Comment: 17 page

Computational Analysis of Changing Wavelength on Bottom Rib and Side Rib Wavy Microchannel Heat Sinks

As the power capacity of microelectronics continues to increase while their volume and size decrease, many different on-chip methods including microchannel heat sinks (MCHS) are being explored to cool down the temperature of these electronics. Wavy MCHS have been proven to yield better heat transfer performance compared to straight MCHS, while only producing a slightly larger pressure drop. This study investigates the heat transfer performance of MCHS following a vertical wavy design and a horizontal wavy design that have the same cross-sectional area. The simulations show that vortices are produced along the channel in the peaks and troughs of the sinusoidal waves which creates mixing within the coolant to better dissipate the heat via convection. The vertical wavy design produces to long symmetrical vortices that travel along the side of the channel, while the horizontal wavy design produces four smaller symmetrical vortices that form at the top, middle, and bottom of the channel. The results show that the horizontal wavy design performs better than the straight and vertical wavy channel especially with a larger decrease in wavelength along the flow direction. Keywords – Heat Transfer, Wavy Microchannel Heat Sinks, Computational Fluid Dynamics (CFD

Retrieval of interatomic separations of molecules from laser-induced high-order harmonic spectra

We illustrate an iterative method for retrieving the internuclear separations of N$_2$, O$_2$ and CO$_2$ molecules using the high-order harmonics generated from these molecules by intense infrared laser pulses. We show that accurate results can be retrieved with a small set of harmonics and with one or few alignment angles of the molecules. For linear molecules the internuclear separations can also be retrieved from harmonics generated using isotropically distributed molecules. By extracting the transition dipole moment from the high-order harmonic spectra, we further demonstrated that it is preferable to retrieve the interatomic separation iteratively by fitting the extracted dipole moment. Our results show that time-resolved chemical imaging of molecules using infrared laser pulses with femtosecond temporal resolutions is possible.Comment: 14 pages, 9 figure

Economics of Carbon Capture and Storage

Human-engineered capture of CO2 emissions at the point source and subsequent long-term storage of this CO2 underground represent a potential mitigation strategy for global warming. The so-called carbon capture and storage (CCS) projects are technically feasible but have not been well established from an economic efficiency perspective. This chapter uses economic theory to describe the costs, benefits, and economically efficient level of CCS provision. Achieving the economically efficient level of CCS provision requires consideration of both the private and public costs and benefits of CCS and will also likely require some degree of government intervention in the form of economic incentives and/or direct regulation

Acute Effects of Static Stretching on Passive Stiffness of the Hamstrings in Healthy Young and Older Women

Static stretching is often performed prior to exercise to increase range of motion (ROM) and reduce passive stiffness of the muscle-tendon unit. A decrease in passive stiffness after stretching is believed to reduce the risk of injury and improve athletic performance. Previous research has demonstrated that an acute bout of static stretching was effective at decreasing passive stiffness in older men. However, to our knowledge, no previous research has examined the acute effects of static stretching on passive stiffness in older women, nor have there been any studies that have compared these effects with a younger female population. PURPOSE: The purpose of this study was to investigate the acute effects of static stretching on passive stiffness of the hamstrings in healthy young and older women. METHODS: Fifteen young (23 ± 4 years) and 15 older (73 ± 5 years) healthy women underwent two passive knee extension assessments before (Pre) and after (Post) two randomized conditions that included a control treatment (quiet resting for two min) and an experimental treatment of static stretching. During the passive knee extension, participants were seated in an upright position with restraining straps placed over the shoulders and right thigh. Each knee extension assessment was administered using a calibrated isokinetic dynamometer programmed in passive mode to extend the leg at 5°∙s-1. All passive knee extensions were performed on the right leg to the point of discomfort but not pain as indicated by the participant, which was regarded as the maximum ROM. Once maximum ROM was reached, the leg was then immediately returned to the baseline position, which was a knee joint angle of 80° below full extension. Passive stiffness (Nm·º-1) was calculated during each knee extension assessment as the final slope of the tangent to the angle-torque curve. For the experimental treatment, four 15-s static stretches were completed in the same manner as the passive knee extension assessments; however, when maximum ROM was reached, the leg was held at this position for 15 s. Each 15-s stretch was separated by 15 s of rest. RESULTS: Passive stiffness (collapsed across group) was lower (P = 0.007) at Post (0.63 ± 0.18 Nm·º-1) compared to Pre (0.72 ± 0.18 Nm·º-1) for the stretching treatment. There was no significant difference (P \u3e 0.999) in passive stiffness between the Pre (0.72 ± 0.18 Nm·º-1) and Post (0.74 ± 0.28 Nm·º-1) time points for the control. The stretch-induced decrease in passive stiffness from Pre to Post was significantly greater (P = 0.049) for the old (-17%) compared to the younger (-5%) women. CONCLUSION: These findings showed that passive stiffness in young and older women decreased after four 15-s static stretches. The greater stretch-induced decrease in passive stiffness observed for the older women suggests that an acute bout of static stretching may be particularly beneficial for alleviating muscle tightness in the elderly. As a result, it may be advantageous for older adults to incorporate static stretching into their warm-up routine prior to exercise, as this may be used to reduce passive stiffness, which could help improve performance and reduce the risk of injury in this population

An Assessment of Factors That Affect the Performance of Air Force O-3 (Captain) Logisticians Working in a Joint Operations Environment.

Joint operations will likely continue to become more prevalent in the future due to defense spending cuts and the nature of modem warfare. Currently, Air Force O-3 (Captain) logisticians, working in the joint operations environment, receive little if any initial training. Exploratory research, by the authors, indicated that these members felt uncertain about their jobs and how they related to the organization, which has been described in the literature as role ambiguity. Consequently, this research project was designed to determine if AF O-3 logisticians serving in the joint operations environment experience more role ambiguity than their counterparts serving in the single service AF environment. With this aim in mind, a mail survey was administered to all Air Force Captains in the Supply, Transportation and Logistics Plans career fields. Of the 695 surveys distributed, 380 were returned (resulting in a 55% return rate), including 332 non-joint and 48 joint responses. Data analysis of joint returns revealed that role ambiguity responses exhibited a bimodal distribution, based on previous joint operations exercise experience. Those members with no exercise experience exhibited statistically higher levels of role ambiguity than their single service counterparts, while those with exercise experience exhibited significantly lower levels

The Effects of Emotional Working Memory Training on Trait Anxiety

Background: Trait anxiety is a pervasive tendency to attend to and experience fears and worries to a disproportionate degree, across various situations. Decreased vulnerability to trait anxiety has been linked to having higher working memory capacity and better emotion regulation; however, the relationship between these factors has not been well-established. Objective: This study sought to determine if participants who undergo emotional working memory training will have significantly lower trait anxiety post-training. The study also sought to determine if emotion regulation mediated the relationship between working memory training and trait anxiety. Method: An experimental group comprising of 49 participants underwent 20 days of computerized emotional working memory training, which involved viewing a continuous stream of emotionally-charged content on a grid, and then remembering the location and color of items presented on the grid. The control group comprised of 51 participants. Results: Participants of the experimental group had significantly lower trait anxiety compared to controls, post-training. Subsequent mediation analysis determined that working memory training capacity gains were significantly related to anxiety reduction as measured by form Y2 of the Spielberger State-Trait Anxiety Inventory (STAI-Y2). Emotion regulation, as measured by the Emotional Regulation Questionnaire (ERQ), was found not to mediate between working memory capacity gains and trait anxiety reduction. Conclusion: Working memory capacity gains and reductions in levels of trait anxiety were observed following emotional working memory training. The study may therefore be useful in informing interventions targeted at improving working memory capacity, and reducing levels of trait anxiety. Moreover, it proposes for future research to further look into the mediating role of emotion regulation via the development or utilization of more comprehensive measures of emotion regulation