945 research outputs found
Paradoxical drying due to salt crystallization
We investigated how salt crystallization inside a porous building material influences the formation of a receding drying front. Nuclear Magnetic Resonance (NMR) is used to measure non-destructively both hydrogen and dissolved sodium ions simultaneously during drying experiments. In this study we focused on the influence of NaCl on the drying. The results show that salt changes the drying process. At low relative humidities (RH ~ 0%), the drying rate of a brick saturated with NaCl solution is much lower than the drying rate of water saturated brick. Moreover, the presence of salt suppresses the development of a receding front. In this case homogenous drying of the material continues till very low saturation values. This is due to salt crystallization near the surface of the brick that causes blockage of the pores. This blockage reduces evaporation rate at the surface and allows maintaining a continuous hydraulic connection between the surface of the porous medium and the liquid present inside the material till low saturation values. Increasing the relative humidity at 55% and 70% RH with the brick saturated with the salt solution leads to a paradoxical situation with evaporation rates greater than for 0% RH. The paradox is explained by the impact of evaporation rate on the efflorescence microstructure, leading to the formation of a blocking crust for sufficiently high evaporation rates and non-blocking efflorescence for sufficiently low evaporation rates. The fundamental difference between the two types of efflorescence is demonstrated from a simple imbibition experiment. Using a simple continuum scale model of drying, critical moisture content was determined and all the essential features of the experimental results are validated. It is shown that critical moisture content can be very low in case of fired-clay brick due to the low threshold of the pore space, which is consistent with the relatively large pore size distribution of the fired-clay brick
Exponential and moment inequalities for U-statistics
A Bernstein-type exponential inequality for (generalized) canonical
U-statistics of order 2 is obtained and the Rosenthal and Hoffmann-J{\o}rgensen
inequalities for sums of independent random variables are extended to
(generalized) U-statistics of any order whose kernels are either nonnegative or
canonicalComment: 22 page
Optimizing working space in laparoscopy: CT-measurement of the effect of neuromuscular blockade and its reversal in a porcine model
Objective: The objective of this paper was to determine the effect of neuromuscular blockade (NMB) on working space in a porcine laparoscopy model. Background: Conflicting results on the effect of NMB on laparoscopic working space are found in literature. Almost all studies are limited by absence of objective assessment of working space or use surrogate outcomes. Methods: In a standardized porcine laparoscopy model, laparoscopic working-space dimensions with and without NMB were investigated in 16 animals using computed tomography at intra-abdominal pressures of 0, 5, 10, and 15Â mmHg during multiple runs of abdominal insufflation. Results: No statistically significant effect of NMB on abdominal dimensions and laparoscopic working-space volume was found during CO2 pneumoperitoneum. In contrast, the effect of pre-stretching of the abdominal wall by a previous abdominal insufflation was found to be significant. Conclusions: This experimental study confirms the results from several clinical studies that NMB does not influence laparoscopic working space. Studies dealing with working space during laparoscopy should take note of pre-stretching bias
Biogeochemical modelling of dissolved oxygen in a changing ocean
Secular decreases in dissolved oxygen concentration have been observed within the tropical oxygen minimum zones (OMZs) and at mid- to high latitudes over the last approximately 50 years. Earth system model projections indicate that a reduction in the oxygen inventory of the global ocean, termed ocean deoxygenation, is a likely consequence of on-going anthropogenic warming. Current models are, however, unable to consistently reproduce the observed trends and variability of recent decades, particularly within the established tropical OMZs. Here, we conduct a series of targeted hindcast model simulations using a state-of-the-art global ocean biogeochemistry model in order to explore and review biases in model distributions of oceanic oxygen. We show that the largest magnitude of uncertainty is entrained into ocean oxygen response patterns due to model parametrization of pCO2-sensitive Câ:âN ratios in carbon fixation and imposed atmospheric forcing data. Inclusion of a pCO2-sensitive Câ:âN ratio drives historical oxygen depletion within the ocean interior due to increased organic carbon export and subsequent remineralization. Atmospheric forcing is shown to influence simulated interannual variability in ocean oxygen, particularly due to differences in imposed variability of wind stress and heat fluxes
Thermoelectric Response of an Interacting Two-Dimensional Electron Gas in Quantizing Magnetic Field
We present a discussion of the linear thermoelectric response of an
interacting electron gas in a quantizing magnetic field. Boundary currents can
carry a significant fraction of the net current passing through the system. We
derive general expressions for the bulk and boundary components of the number
and energy currents. We show that the local current density may be described in
terms of ``transport'' and ``internal magnetization'' contributions. The latter
carry no net current and are not observable in standard transport experiments.
We show that although Onsager relations cannot be applied to the local current,
they are valid for the transport currents and hence for the currents observed
in standard transport experiments. We relate three of the four thermoelectric
response coefficients of a disorder-free interacting two-dimensional electron
gas to equilibrium thermodynamic quantities. In particular, we show that the
diffusion thermopower is proportional to the entropy per particle, and we
compare this result with recent experimental observations.Comment: 18 pages, 2 postscript figures included. Revtex with epsf.tex and
multicol.sty. In the revised version, the comparison with experimental
observations at is extended to include the possibility of
corrections due to weak impurity scattering. The conclusions that we reach
regarding the applicability of the composite fermion model at these filling
fractions are not affecte
Quantitative proteomic analysis reveals concurrent RNA-protein interactions and identifies new RNA-binding proteins in Saccharomyces cerevisiae
A growing body of evidence supports the existence of an extensive network of RNA-binding proteins (RBPs) whose combinatorial binding affects the post-transcriptional fate of every mRNA in the cell-yet we still do not have a complete understanding of which proteins bind to mRNA, which of these bind concurrently, and when and where in the cell they bind. We describe here a method to identify the proteins that bind to RNA concurrently with an RBP of interest, using quantitative mass spectrometry combined with RNase treatment of affinity-purified RNA-protein complexes. We applied this method to the known RBPs Pab1, Nab2, and Puf3. Our method significantly enriched for known RBPs and is a clear improvement upon previous approaches in yeast. Our data reveal that some reported protein-protein interactions may instead reflect simultaneous binding to shared RNA targets. We also discovered more than 100 candidate RBPs, and we independently confirmed that 77% (23/30) bind directly to RNA. The previously recognized functions of the confirmed novel RBPs were remarkably diverse, and we mapped the RNA-binding region of one of these proteins, the transcriptional coactivator Mbf1, to a region distinct from its DNA-binding domain. Our results also provided new insights into the roles of Nab2 and Puf3 in post-transcriptional regulation by identifying other RBPs that bind simultaneously to the same mRNAs. While existing methods can identify sets of RBPs that interact with common RNA targets, our approach can determine which of those interactions are concurrent-a crucial distinction for understanding post-transcriptional regulation
Towards a Phenomenology of Grief : insights from Merleau-Ponty
This paper shows how phenomenological research can enhance our understanding of what it is to experience grief. I focus specifically on themes in the work of Maurice Merleau-Ponty, in order to develop an account that emphasizes two importantly different ways of experiencing indeterminacy. This casts light on features of grief that are disorienting and difficult to describe, while also making explicit an aspect of experience upon which the possibility of phenomenological inquiry itself depends
The Clean Power Plan: Issues to Watch
Although the Clean Air Act is an imperfect tool for addressing the nationâs greenhouse gas emissions, it is the only available federal mechanism for directly addressing power plant carbon emissions. The Obama Administrationâs Clean Power Plan, published in final form in August 2015, tackles the challenge. This paper from the Center for Progressive Reform (CPR) compiles 13 separately authored essays from 11 CPR Member Scholars, each addressing a different topic related to the Clean Power Plan, and each representing the expertise and views of its individual author(s). Published in July 2015, just before the release of the final rule, the essays tee up key questions about the ruleâs legality, implications for the energy sector, and a series of discrete implementation questions, including the role of cap-and-trade (and offsets), the nature and distribution of state targets, and implications for environmental justice
The Clean Power Plan: Issues to Watch
Although the Clean Air Act is an imperfect tool for addressing the nationâs greenhouse gas emissions, it is the only available federal mechanism for directly addressing power plant carbon emissions. The Obama Administrationâs Clean Power Plan, published in final form in August 2015, tackles the challenge. This paper from the Center for Progressive Reform (CPR) compiles 13 separately authored essays from 11 CPR Member Scholars, each addressing a different topic related to the Clean Power Plan, and each representing the expertise and views of its individual author(s). Published in July 2015, just before the release of the final rule, the essays tee up key questions about the ruleâs legality, implications for the energy sector, and a series of discrete implementation questions, including the role of cap-and-trade (and offsets), the nature and distribution of state targets, and implications for environmental justice
Psychogenic Elaboration of Simple Partial Seizures
Seizures that cause loss of consciousness (LOC) can be classified as epileptic or nonepileptic based on evaluation of ictal semiology and analysis of changes in EEG events, recorded with continuous scalp EEG and video monitoring. We report 3 patients who had hippocampal electrographic seizures documented with intracranial EEG recording with no accompanying scalp EEG change immediately preceding psychogenic unresponsiveness. Each patient also had complex partial seizures (CPS) originating in the hippocampus. Some individuals can have complex interactions of epileptic and nonepileptic seizures.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66184/1/j.1528-1157.1995.tb00471.x.pd
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