Differential Actions of Ethanol and Trichloroethanol at Sites in the M3 and M4 Domains of the NMDA Receptor GluN2A (NR2A) Subunit

Background and purpose:  Alcohol produces its behavioural effects in part due to inhibition of N-methyl-d-aspartate (NMDA) receptors in the CNS. Previous studies have identified amino acid residues in membrane-associated domains 3 (M3) and 4 (M4) of the NMDA receptor that influence ethanol sensitivity. In addition, in other alcohol-sensitive ion channels, sedative-hypnotic agents have in some cases been shown to act at sites distinct from the sites of ethanol action. In this study, we compared the influence of mutations at these sites on sensitivity to ethanol and trichloroethanol, a sedative-hypnotic agent that is a structural analogue of ethanol. Experimental approach:  We constructed panels of mutants at ethanol-sensitive positions in the GluN2A (NR2A) NMDA receptor subunit and transiently expressed these mutants in human embryonic kidney 293 cells. We used whole-cell patch-clamp recording to assess the actions of ethanol and trichloroethanol in these mutant NMDA receptors. Key results:  Ethanol sensitivity of mutants at GluN2A(Ala825) was not correlated with any physicochemical measures tested. Trichloroethanol sensitivity was altered in two of three ethanol-insensitive mutant GluN2A subunits: GluN2A(Phe637Trp) in M3 and GluN2A(Ala825Trp) in M4, but not GluN2A(Met823Trp). Trichloroethanol sensitivity decreased with increasing molecular volume at Phe637 or increasing hydrophobicity at Ala825 and was correlated with ethanol sensitivity at both sites. Conclusions and implications:  Evidence obtained to date is consistent with a role of GluN2A(Ala825) as a modulatory site for ethanol and trichloroethanol sensitivity, but not as a binding site. Trichloroethanol appears to inhibit the NMDA receptor in a manner similar, but not identical to, that of ethanol

Exploration of the material property space for chemical looping air separation applied to carbon capture and storage

Oxy-fuel combustion is one route to large scale carbon capture and storage. Fuel is combusted in oxygen rather than air, allowing pure CO2 to be captured and sequestered. Currently, the required oxygen is produced via cryogenic air separation, which imposes a significant energy penalty. Chemical looping air separation (CLAS) is an alternative process for the production of oxygen, and relies on the repeated oxidation and reduction of solid oxygen carriers (typically metal oxides). The energy efficiency is governed by the thermodynamic properties of the oxygen carrier material, and how well the CLAS process can be heat-integrated with the process consuming oxygen. In this study, key thermodynamic properties have been identified and assessed using a steady state model of a CLAS-oxy-fuel power plant. It is demonstrated that energy penalties as low as 1.5 percentage points can be obtained for a narrow range of material properties. Based on density functional theory calculations, 14 oxygen carrier systems, which are novel or have received little attention, have been identified that could potentially achieve this minimal energy penalt

Assessing 3D tunnel position in ACL reconstruction using a novel single image 3D-2D registration

Poster Session: 2D/3D and FluoroscopyConference Theme: Image-Guided Procedures, Robotic Interventions, and ModelingThe routinely used procedure for evaluating tunnel positions following anterior cruciate ligament (ACL) reconstructions based on standard X-ray images is known to pose difficulties in terms of obtaining accurate measures, especially in providing three-dimensional tunnel positions. This is largely due to the variability in individual knee joint pose relative to X-ray plates. Accurate results were reported using postoperative CT. However, its extensive usage in clinical routine is hampered by its major requirement of having CT scans of individual patients, which is not available for most ACL reconstructions. These difficulties are addressed through the proposed method, which aligns a knee model to X-ray images using our novel single-image 3D-2D registration method and then estimates the 3D tunnel position. In the proposed method, the alignment is achieved by using a novel contour-based 3D-2D registration method wherein image contours are treated as a set of oriented points. However, instead of using some form of orientation weighting function and multiplying it with a distance function, we formulate the 3D-2D registration as a probability density estimation using a mixture of von Mises-Fisher- Gaussian (vMFG) distributions and solve it through an expectation maximization (EM) algorithm. Compared with the ground-truth established from postoperative CT, our registration method in an experiment using a plastic phantom showed accurate results with errors of (-0.43°±1.19°, 0.45°±2.17°, 0.23°±1.05°) and (0.03±0.55, -0.03±0.54, -2.73±1.64) mm. As for the entry point of the ACL tunnel, one of the key measurements, it was obtained with high accuracy of 0.53±0.30 mm distance errors. © 2012 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).published_or_final_versionSPIE Medical Imaging 2012, San Diego, CA., 4-9 February 2012. In Progress in Biomedical Optics and Imaging, 2012, v. 8316, art. no. 83162

Correspondenceless 3D-2D registration based on expectation conditional maximization

Cum Laude Poster AwardConference Theme: Visualization, Image-Guided Procedures, and Modeling3D-2D registration is a fundamental task in image guided interventions. Due to the physics of the X-ray imaging, however, traditional point based methods meet new challenges, where the local point features are indistinguishable, creating difficulties in establishing correspondence between 2D image feature points and 3D model points. In this paper, we propose a novel method to accomplish 3D-2D registration without known correspondences. Given a set of 3D and 2D unmatched points, this is achieved by introducing correspondence probabilities that we model as a mixture model. By casting it into the expectation conditional maximization framework, without establishing one-to-one point correspondences, we can iteratively refine the registration parameters. The method has been tested on 100 real X-ray images. The experiments showed that the proposed method accurately estimated the rotations (< 1°) and in-plane (X-Y plane) translations (< 1 mm). © 2011 SPIE.published_or_final_versionThe SPIE Medical Imaging 2011, Lake Buena Vista, FL., 12-17 February 2011. In Progress in Biomedical Optics and Imaging, 2011, v. 7964, art. no. 79642

On the Thermoelectric Effect of Interface Imperfections

Ordinary thermocouples use the well-known Seebeck effect to measure the temperature at the junction of two different conductors. The electromotive force generated by the heat depends on the difference between the respective thermoelectric powers of the contacting metals and the junction temperature. Figure 1 shows the schematic diagram of the thermoelectric measurement as most often used in nondestructive materials characterization. One of the reference electrodes is heated by electrical means to a preset temperature of 100 – 300 °C, pretty much like the tip of a temperature-stabilized soldering iron, and connected to the inverting (−) input of the differential amplifier driving the indicator. The other electrode is left cold at essentially room temperature and connected to the non-inverting (+) input. The measurement is done quickly in a few seconds to assure (i) that the hot reference electrode is not cooled down perceivably by the specimen and (ii) that the rest of the specimen beyond the close vicinity of the contact point is not warmed up perceivably. Ideally, regardless of the temperature difference between the junctions, only thermocouples made of different materials, i.e., materials of different thermoelectric power, will generate thermoelectric signal. This unique feature makes the simple thermoelectric tester one of the most sensitive material discriminators used in nondestructive inspection

Impact of monovalent cation halide additives on the structural and optoelectronic properties of CH<inf>3</inf>NH<inf>3</inf>PbI<inf>3</inf> perovskite

The influence of monovalent cation halide additives on the optical, excitonic, and electrical properties of CH$_{3}$NH$_{3}$PbI$_{3}$ perovskite is reported. Monovalent cation halide with similar ionic radii to Pb$^{2+}$, including Cu$^{+}$, Na$^{+}$, and Ag$^{+}$, have been added to explore the possibility of doping. Significant reduction of sub-bandgap optical absorption and lower energetic disorder along with a shift in the Fermi level of the perovskite in the presence of these cations has been observed. The bulk hole mobility of the additive-based perovskites as estimated using the space charge limited current method exhibits an increase of up to an order of magnitude compared to the pristine perovskites with a significant decrease in the activation energy. Consequentially, enhancement in the photovoltaic parameters of additive-based solar cells is achieved. An increase in open circuit voltage for AgI (≈1.02 vs 0.95 V for the pristine) and photocurrent density for NaI- and CuBr-based solar cells (≈23 vs 21 mA cm$^{−2}$ for the pristine) has been observed. This enhanced photovoltaic performance can be attributed to the formation of uniform and continuous perovskite film, better conversion, and loading of perovskite, as well as the enhancement in the bulk charge transport along with a minimization of disorder, pointing towards possible surface passivation.M.A.J. thanks Nyak Technology Limited for a PhD scholarship. M.I.D., S.M.Z., and M.G. thank the King Abdulaziz City for Science and Technology (KACST) and Swiss National Science Foundation (SNSF) for financial support. N.A. gratefully acknowledges financial support from the Swiss confederation under Swiss Government Scholarship program. The authors would like to thank Dr. Pierre Mettraux in Molecular and Hybrid Materials Characterization Center, EPFL for carrying out XPS measurements. A.S. gratefully acknowledges financial support from the Indo-UK APEX project. S.P.S. acknowledges Royal Scociety London for the Newton Fellowship. R.H.F, M.A.J., and A.S. would like to acknowledge the support from EPSRC.This is the author accepted manuscript. The final version is available from Wiley via http://dx.doi.org/10.1002/aenm.20150247

Vigorous star formation hidden by dust in a galaxy at z=1.4z=1.4

Near-infrared surveys have revealed a substantial population of enigmatic faint galaxies with extremely red optical-to-near-infrared colours and with a sky surface density comparable to that of faint quasars. There are two scenarios for these extreme colours: (i) these distant galaxies have formed virtually all their stars at very high redshifts and, due to the absence of recently formed stars, the colours are extremely red and (ii) these distant galaxies contain large amounts of dust, severely reddening the rest-frame UV--optical spectrum. HR10 ($z = 1.44$) is considered the archetype of the extremely red galaxies. Here we report the detection of the continuum emission from HR10 at 850$\mu$m and at 1250$\mu$m, demonstrating that HR10 is a very dusty galaxy undergoing a major episode of star formation. Our result provides a clear example of a high-redshift galaxy where the star formation rate inferred from the ultraviolet luminosity would be underestimated by a factor up to 1000, and shows that great caution should be used to infer the global star formation history of the Universe from optical observations only.Comment: 12 pages, 1 figure, Nature, in press (30 April 1998

TEMPRANILLO is a regulator of juvenility in plants

Many plants are incapable of flowering in inductive daylengths during the early juvenile vegetative phase (JVP). Arabidopsis mutants with reduced expression of TEMPRANILLO (TEM), a repressor of FLOWERING LOCUS T (FT) had a shorter JVP than wild-type plants. Reciprocal changes in mRNA expression of TEM and FT were observed in both Arabidopsis and antirrhinum, which correlated with the length of the JVP. FT expression was induced just prior to the end of the JVP and levels of TEM1 mRNA declined rapidly at the time when FT mRNA levels were shown to increase. TEM orthologs were isolated from antirrhinum (AmTEM) and olive (OeTEM) and were expressed most highly during their juvenile phase. AmTEM functionally complemented AtTEM1 in the tem1 mutant and over-expression of AmTEM prolonged the JVP through repression of FT and CONSTANS (CO). We propose that TEM may have a general role in regulating JVP in herbaceous and woody species

A 3D computed tomography based tool for orthopedic surgery planning

Series : Lecture notes in computational vision and biomechanics, vol. 19The preparation of a plan is essential for a surgery to take place in the best way possible and also for shortening patient’s recovery times. In the orthopedic case, planning has an accentuated significance due to the close relation between the degree of success of the surgery and the patient recovering time. It is important that surgeons are provided with tools that help them in the planning task, in order to make it more reliable and less time consuming. In this paper, we present a 3D Computed Tomography based solution and its implementation as an OsiriX plugin for orthopedic surgery planning. With the developed plugin, the surgeon is able to manipulate a three-dimensional isosurface rendered from the selected imaging study (a CT scan). It is possible to add digital representations of physical implants (surgical templates), in order to evaluate the feasibility of a plan. These templates are STL files generated from CAD models. There is also the feature to extract new isosurfaces of different voxel values and slice the final 3D model according to a predefined plane, enabling a 2D analysis of the planned solution. Finally, we discuss how the proposed application assists the surgeon in the planning process in an alternative way, where it is possible to three-dimensionally analyze the impact of a surgical intervention on the patient.(undefined

Transmission characteristics of EM wave in a finite thickness plasma

One of the key factors for solving the problems of re-entry communication interruption is electromagnetic (EM) wave transmission characteristics in a plasma. Theoretical and experimental studies were carried out on specific transmission characteristics for different plasma sheath characteristic under thin sheath condition in re-entry state. The paper presents systematic studies on the variations of wave attenuation characteristics versus plasma sheath thickness L, collision frequency &nu;, electron density ne and wave working frequency f in a &phi; 800mm high temperature shock tube. In experiments, L is set to 4 cm and 38 cm. &nu; is 2 GHz and 15 GHz. ne is from 1&times;10^10 cm&minus;3 to 1&times;10^13 cm&minus;3, and f is set to 2, 5, 10, 14.6 GHz, respectively. Meanwhile, Wentzel&ndash;Kramers&ndash;Brillouin (WKB) and finite-difference time-domain (FDTD) methods are adopted to carry out theoretical simulation for comparison with experimental results. It is found that when L is much larger than EM wavelength &lambda; (thick sheath) and &nu; is large, the theoretical result is in good agreement with experimental one, when sheath thickness L is much larger than &lambda;, while &nu; is relatively small, two theoretical results are obviously different from the experimental ones. It means that the existing theoretical model can not fully describe the contribution of &nu;. Furthermore, when L and &lambda; are of the same order of magnitude (thin sheath), the experimental result is much smaller than the theoretical values, which indicates that the current model can not properly describe the thin sheath effect on EM attenuation characteristics