Improved Tensor Current Limit from ^{8}B β Decay Including New Recoil-Order Calculations

A precision measurement of the β^{+} decay of ^{8}B was performed using the Beta-decay Paul Trap to determine the β-ν angular correlation coefficient a_{βν}. The experimental results were combined with new ab initio symmetry-adapted no-core shell-model calculations to yield the second-most precise measurement from Gamow-Teller decays, a_{βν}=-0.3345±0.0019_{stat}±0.0021_{syst}. This value agrees with the standard model value of -1/3 and improves uncertainties in ^{8}B by nearly a factor of 2. By combining results from ^{8}B and ^{8}Li, a tight limit on tensor current coupling to right-handed neutrinos was obtained. A recent global evaluation of all other precision β decay studies suggested a nonzero value for right-handed neutrino coupling in contradiction with the standard model at just above 3σ. The present results are of comparable sensitivity and do not support this finding.

Screening H3 Histone Acetylation in a Wild Bird, the House Sparrow (Passer Domesticus)

Epigenetic mechanisms are increasingly understood to have major impacts across ecology. However, one molecular epigenetic mechanism, DNA methylation, currently dominates the literature. A second mechanism, histone modification, is likely important to ecologically relevant phenotypes and thus warrants investigation, especially because molecular interplay between methylation and histone acetylation can strongly affect gene expression. There are a limited number of histone acetylation studies on non-model organisms, yet those that exist show that it can impact gene expression and phenotypic plasticity. Wild birds provide an excellent system to investigate histone acetylation, as free-living individuals must rapidly adjust to environmental change. Here, we screen histone acetylation in the house sparrow (Passer domesticus); we studied this species because DNA methylation was important in the spread of this bird globally. This species has one of the broadest geographic distributions in the world, and part of this success is related to the way that it uses methylation to regulate its gene expression. Here, we verify that a commercially available assay that was developed for mammals can be used in house sparrows. We detected high variance in histone acetylation among individuals in both liver and spleen tissue. Further, house sparrows with higher epigenetic potential in the Toll Like Receptor-4 (TLR-4) promoter (i.e., CpG content) had higher histone acetylation in liver. Also, there was a negative correlation between histone acetylation in spleen and TLR-4 expression. In addition to validating a method for measuring histone acetylation in wild songbirds, this study also shows that histone acetylation is related to epigenetic potential and gene expression, adding a new study option for ecological epigenetics.

Direct Mass Measurements to Inform the Behavior of ^{128m}Sb in Nucleosynthetic Environments

Nuclear isomer effects are pivotal in understanding nuclear astrophysics, particularly in the rapid neutron-capture process where the population of metastable isomers can alter the radioactive decay paths of nuclei produced during astrophysical events. The β-decaying isomer ^{128m}Sb was identified as potentially impactful since the β-decay pathway along the A=128 isobar funnels into this state bypassing the ground state. We report the first direct mass measurements of the ^{128}Sb isomer and ground state using the Canadian Penning Trap mass spectrometer at Argonne National Laboratory. We find mass excesses of -84564.8(25)  keV and -84608.8(21)  keV, respectively, resulting in an excitation energy for the isomer of 43.9(33) keV. These results provide the first key nuclear data input for understanding the role of ^{128m}Sb in nucleosynthesis, and we show that it will influence the flow of the rapid neutron-capture process.

Improved Limit on Tensor Currents in the Weak Interaction from ^{8}Li β Decay

The electroweak interaction in the standard model is described by a pure vector-axial-vector structure, though any Lorentz-invariant component could contribute. In this Letter, we present the most precise measurement of tensor currents in the low-energy regime by examining the β-ν[over ¯] correlation of trapped ^{8}Li ions with the Beta-decay Paul Trap. We find a_{βν}=-0.3325±0.0013_{stat}±0.0019_{syst} at 1σ for the case of coupling to right-handed neutrinos (C_{T}=-C_{T}^{'}), which is consistent with the standard model prediction.

Build Up and Characterization of Ultraslow Nuclear Burn-Up Wave in Epithermal Neutron Multiplying Medium

A study is carried out on the build-up and characterization of ultraslow nuclear burn-up wave in epithermal neutron multiplying medium for slab geometry. Uranium-plutonium fissile medium is considered for the calculation. Transient part of the wave is characterized by transient time (TT), transient length (TL), and TT and TL are defined as the time and distance required to develop asymptotic neutron flux propagating through the media. Steady-state part of the wave is characterized with wave velocity and reaction zone width (full width half maximum (FWHM) and full width 10% of maximum (FW10M)). Parametric studies are carried out for different enrichment of 235U and different values of external source of neutron. It is observed that TT, TL, FWHM, and FW10M decrease with the increase in enrichment. The velocity of the wave increases with the enrichment of 235U. This study is beneficial for understanding the characteristics of nuclear burn-up wave in epithermal region as it will help in further researches in this area.

Guideline for the management of hip fractures 2020: Guideline by the Association of Anaesthetists

We convened a multidisciplinary Working Party on behalf of the Association of Anaesthetists to update the 2011 guidance on the peri-operative management of people with hip fracture. Importantly, these guidelines describe the core aims and principles of peri-operative management, recommending greater standardisation of anaesthetic practice as a component of multidisciplinary care. Although much of the 2011 guidance remains applicable to contemporary practice, new evidence and consensus inform the additional recommendations made in this document. Specific changes to the 2011 guidance relate to analgesia, medicolegal practice, risk assessment, bone cement implantation syndrome and regional review networks. Areas of controversy remain, and we discuss these in further detail, relating to the mode of anaesthesia, surgical delay, blood management and transfusion thresholds, echocardiography, anticoagulant and antiplatelet management and postoperative discharge destination. Finally, these guidelines provide links to supplemental online material that can be used at readers' institutions, key references and UK national guidance about the peri-operative care of people with hip and periprosthetic fractures during the COVID-19 pandemic.

Analysis of Loss of Heat Sink for ITER Divertor Cooling System Using Modified RELAP/SCDAPSIM/MOD 4.0

The present work includes thermal hydraulic modeling and analysis of loss of heat sink (LOHS) accident for the ITER divertor cooling system. The analysis is done for the new design of full tungsten divertor. The new design is also analyzed for different local heat loads ranging from 10 MW/m2 to 20 MW/m2 (while maintaining the total heat load 200 MW) under the steady-state fluid conditions. The LOHS event is selected since divertor is the most sensitive component to loss or reduction in coolability of divertor primary heat transport system (DV-PHTS) loop as it receives large heat flux from plasma. The main objective of this analysis is to find margins to unwanted conditions like overstress temperatures of structure and elevated water level in the pressurizer. The analysis is done by modified thermal hydraulic code RELAP/SCDAPSIM/MOD 4.0. The results obtained are compared with the results of old divertor design which uses carbon fiber composite (CFC) layer to show that how the new design of divertor behaves compared to the older design under the accident scenario. A detailed model of DV-PHTS loop and its ancillary system is presented. The model includes promotional integral differential (PID) controller for controlling the pressurizer heater and spray system. A detailed pump model is also included in the present analysis which was previously used as a time-dependent junction. The analysis shows that under the accident scenario, (a) the divertor structure temperature at the critical sites (inner vertical target (IVT) and outer vertical target (OVT)) is always within the design limit and does not affect the structural integrity of the divertor. (b) The water level in the pressurizer increases moderately and finely controlled by the PID controller, and pressurizer safety valve does not open.

Lanreotide vs octreotide LAR for patients with advanced gastroenteropancreatic neuroendocrine tumors: An observational time and motion analysis

BACKGROUND

Lanreotide and octreotide acetate suspension for injectable (LAR) are both recommended for clinical use in patients with locally advanced or metastatic gastroenteropancreatic neuroendocrine tumors. However, each agent possesses unique attributes in terms of their drug-delivery characteristics. The study objective was to compare overall drug-delivery efficiency between lanreotide and octreotide LAR in gastroenteropancreatic neuroendocrine tumor patients.

METHODS

This study employed an observational time and motion design among patients treated with lanreotide or octreotide LAR across five US cancer centers. Baseline patient data collection included age, disease grade and duration, prior therapies and performance status. Drug-delivery time (drug preparation and administration), total patient time and resource use data were collected for gastroenteropancreatic neuroendocrine tumors receiving lanreotide (n = 22) or octreotide LAR (n = 22). Following each administration, qualitative data on the drug-delivery experience was collected from patients and nurses.

RESULTS

Lanreotide was associated with a significant reduction in mean delivery time (2.5 min; 95% CI:2.0 to 3.1) compared to octreotide LAR (6.2 min; 95%CI: 4.4 to 7.9; p = 0.004). The mean total patient time for lanreotide and octreotide LAR was comparable between groups (32.1 vs. 36.6 minutes; p = 0.97). Nurses reported increased concerns with octreotide LAR related to needle clogging (p = 0.034) and device failures (p = 0.057). Overall, lanreotide had a median satisfaction score of 5.0 compared to a score of 4.0 with octreotide LAR (p = 0.03).

CONCLUSIONS

Lanreotide was associated with significant reductions in drug-delivery time compared to octreotide LAR, which contributed to an improvement in overall healthcare efficiency.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT03017690.

Impacts of photochemical ageing on the half-lives and diagnostic ratio of polycyclic aromatic hydrocarbons intrinsic to PM2.5 collected from 'real-world' like combustion events of wood and rice straw burning

The present experimental study describes the characteristics of polycyclic aromatic hydrocarbons (PAHs) emitted with PM_2.5 particles during wood and rice straw burning as well as impacts of photochemical ageing on the half lives of particulate PAHs and their diagnostic ratio values. The photochemical degradation kinetics experiments were carried out by exposing the PM_2.5 to light and synthetic air flow. Pseudo first order rate constants were calculated based on PAH loss as a function of exposure time. Relatively quick degradation of lighter PAHs (3-rings) [(0.2-0.5)h^-1] than heavier PAHs (4-6 rings) [(0.0005-0.03)h^-1] indicates substantial impact of PAH-substrate interaction through π-π stacking with the carbonaceous substrates. Moreover, our results showed distinct PAH diagnostic ratios (DR) for wood and rice straw burnings which, however, change with time due to photochemical degradation. The later may add uncertainties in the applications of DR values for source apportionment. Furthermore, considerably large half lives (100-3000 h) of the carcinogenic PAHs as estimated under ambient solar radiation may cause poor and adverse air quality in long range and therefore demands immediate regulations against uncontrolled biomass burning.

Hygroscopic Coating of Sulfuric Acid Shields Oxidant Attack on the Atmospheric Pollutant Benzo(a)pyrene Bound to Model Soot Particles

Substantial impacts on climate have been documented for soot‒sulfuric acid (H₂SO₄) interactions in terms of optical and hygroscopic properties of soot aerosols. However, the influence of H₂SO₄ on heterogeneous chemistry on soot remains unexplored. Additionally, oxidation rate coefficients for polycyclic aromatic hydrocarbons intrinsic to the atmospheric particles evaluated in laboratory experiments seem to overestimate their degradation in ambient atmosphere, possibly due to matrix effects which are hitherto not mimicked in laboratory experiments. For the first time, our kinetics study reports significant influence of H₂SO₄ coating on heterogeneous ozonation of benzo(a)pyrene (BaP) deposited on model soot, representative to atmospheric particles. The approximate specific surface area of model soot (5 m²g⁻¹) was estimated as a measure of the availability of surface molecules to a typical gaseous atmospheric oxidant. Heterogeneous bimolecular reaction kinetics and Raman spectroscopy studies suggested plausible reasons for decreased BaP ozonation rate in presence of H₂SO₄: 1. decreased partitioning of O₃ on soot surface and 2. shielding of BaP molecules to gaseous O₃ by acid-BaP reaction or O₃ oxidation products.

VUV and XUV reflectance of optically coated mirrors for selection of high harmonics

We report the reflectance, ~1° from normal incidence, of six different mirrors as a function of photon energy, using monochromatic vacuum ultraviolet (VUV) and extreme ultraviolet (XUV) radiation with energies between 7.5 eV and 24.5 eV. The mirrors examined included both single and multilayer optical coatings, as well as an uncoated substrate. We discuss the performance of each mirror, paying particular attention to the potential application of suppression and selection of high-order harmonics of a Ti:sapphire laser.

Time resolved 3D momentum imaging of ultrafast dynamics by coherent VUV-XUV radiation

We present a new experimental setup for measuring ultrafast nuclear and electron dynamics of molecules after photo-excitation and ionization. We combine a high flux femtosecond vacuum ultraviolet (VUV) and extreme ultraviolet (XUV) source with an internally cold molecular beam and a 3D momentum imaging particle spectrometer to measure electrons and ions in coincidence. We describe a variety of tools developed to perform pump-probe studies in the VUV-XUV spectrum and to modify and characterize the photon beam. First benchmark experiments are presented to demonstrate the capabilities of the system.

Hetero-site-specific X-ray pump-probe spectroscopy for femtosecond intramolecular dynamics

New capabilities at X-ray free-electron laser facilities allow the generation of two-colour femtosecond X-ray pulses, opening the possibility of performing ultrafast studies of X-ray-induced phenomena. Particularly, the experimental realization of hetero-site-specific X-ray-pump/X-ray-probe spectroscopy is of special interest, in which an X-ray pump pulse is absorbed at one site within a molecule and an X-ray probe pulse follows the X-ray-induced dynamics at another site within the same molecule. Here we show experimental evidence of a hetero-site pump-probe signal. By using two-colour 10-fs X-ray pulses, we are able to observe the femtosecond time dependence for the formation of F ions during the fragmentation of XeF2 molecules following X-ray absorption at the Xe site.

Serum lipoprotein ratios as markers of insulin resistance: a study among non-diabetic acute coronary syndrome patients with impaired fasting glucose

BACKGROUND & OBJECTIVES

Recent data suggest that insulin resistance can predict cardiovascular disease independently of the other risk factors, such as hypertension, visceral obesity or dyslipidaemia. However, the majority of available methods to evaluate insulin resistance are complicated to operate, expensive, and time consuming. This study was undertaken to assess whether serum lipoprotein ratios could predict insulin resistance in non-diabetic acute coronary syndrome (ACS) patients.

METHODS

Ninety non-diabetic patients with impaired fasting glucose admitted with a diagnosis of ACS were included in the study. At the time of admission fasting glucose and insulin concentrations were measured. The homeostatic model assessment-insulin resistance (HOMA-IR) was used for insulin resistance. The fasting serum total cholesterol (TC), triglycerides (TG) and high density lipoprotein cholesterol (HDL-C) levels were checked, and then TC/HDL-C and TG/HDL-C ratios were calculated. The areas under the curves (AUC) of the receiver operating characteristic (ROC) curves were used to compare the power of these serum lipoprotein ratios as markers.

RESULTS

Lipoprotein ratios were significantly higher in patients with HOMA-IR index > 2.5 as compared to patients with index <2.5 (P < 0.05). Both TG/HDL-C and TC/HDL-C ratios were significantly correlated with HOMA-IR (P<0.05). The area under the ROC curve of the TG/HDL-C and TC/HDL-C ratio for predicting insulin resistance was 0.80 (95% CI, 0.67 to 0.93), 0.78 (95% CI, 0.65 to 0.91), respectively.

INTERPRETATION & CONCLUSIONS

The findings of this study demonstrate that serum lipoprotein ratios can provide a simple means of identifying insulin resistance and can be used as markers of insulin resistance and cardiovascular diseases risk in adult non-diabetic patients.

Facilitators and barriers to the increased supervisory role of senior charge nurses: a qualitative study

AIMS

To explore the experiences of senior charge nurses provided with 'increased supervisory hours'.

BACKGROUND

Designated supervisory time is essential for senior charge nurses to provide effective clinical leadership. It is important to explore the impact arises of such an increase.

METHODS

An online questionnaire collected exploratory data from senior charge nurses (n = 60). Semi-structured interviews gathered in-depth qualitative data (n = 12). Findings were analysed for common themes associated with implementation of the increased senior charge nurse supervisory role.

RESULTS

The majority of senior charge nurses were unable to use their full allocation of supervisory time. They struggled to accomplish leadership goals because of managing staffing levels, increased workload, time constraints and limited support. Factors that facilitated the role included preparation and support, adequate staff capacity, effective leadership skills and availability of supervisory time. The senior charge nurses took pride in providing clinical leadership, promoting staff development and delivering patient care. Support, in terms of preparation, capacity building and ongoing mentoring, was a key factor for achieving senior charge nurse goals.

CONCLUSION

Senior charge nurses should be supported to maximise supervisory time through the provision of an induction programme, formal coaching and ongoing training and development.

IMPLICATIONS FOR NURSING MANAGEMENT

Preparation and support is essential for senior charge nurses to deliver enhanced clinical leadership through increased supervisory time.

The effect of ethnicity on in-hospital mortality following emergency abdominal surgery: a national cohort study using Hospital Episode Statistics

OBJECTIVES

Ethnicity has complex effects on health and the delivery of health care in part related to language and cultural barriers. This may be important in patients requiring emergency abdominal surgery where delays have profound impact on outcomes. The aim here was to test if variations in outcomes (e.g. in-hospital mortality) exist by ethnic group following emergency abdominal surgery.

STUDY DESIGN

Retrospective cohort study using population-level routinely collected administrative data from England (Hospital Episode Statistics).

METHODS

Adult patients undergoing emergency abdominal operations between April 2008 and March 2012 were identified. Operations were divided into: 'major', 'hepatobiliary' or 'appendectomy/minor'. The primary outcome was all cause in-hospital mortality. Univariable and multivariable analysis odds ratios (OR with 95% confidence intervals, CI) adjusting for selected factors were performed.

RESULTS

359,917 patients were identified and 80.7% of patients were White British, 4.7% White (Other), 2.4% Afro-Caribbean, 1.6% Indian, 2.6% Chinese, 3.1% Asian (Other) and 4.9% not known, with crude in-hospital mortality rates of 4.4%, 3.1%, 2.0%, 2.6%, 1.6%, 1.7% and 5.17%, respectively. The majority of patients underwent appendectomy/minor (61.9%) compared to major (20.9%) or hepatobiliary (17.2%) operations (P < 0.001) with an in-hospital mortality of 1.7%, 11.5% and 3.9% respectively. Adjusted mortality was largely similar across ethnic groups except where ethnicity was not recorded (compared to White British patients following major surgery OR 2.05, 95% 1.82-2.31, P < 0.01, hepatobiliary surgery OR 2.78, 95% CI 2.31-3.36, P = 0.01 and appendectomy/minor surgery OR 1.78, 95% 1.52-2.08, P < 0.01).

CONCLUSIONS

Ethnicity is not associated with poorer outcomes following emergency abdominal surgery. However, ethnicity is not recorded in 5% of this cohort and this represents an important, yet un-definable, group with significantly poorer outcomes.

Influence of day of surgery on mortality following elective colorectal resections

BACKGROUND

The aim of this study was to investigate whether the increased mortality previously identified for surgery performed on Fridays was apparent following major elective colorectal resections and how this might be affected by case mix.

METHODS

Patients undergoing elective colorectal resections in England from 2001 to 2011 were identified using Hospital Episode Statistics. Propensity scores were used to match patients having operations on a Friday in a 1 : 1 ratio with those undergoing surgery on other weekdays. Multivariable analyses were used to investigate overall deaths within 1 year of operation.

RESULTS

A total of 204,669 records were extracted for patients undergoing major elective colorectal resections. Patients who had surgery on Fridays were more deprived (4780 (17.1 per cent) of 27,920 versus 28,317 (16.0 per cent) of 176,749; P < 0.001), a greater proportion had had an emergency admission in the 3 previous months (7870 (28.2 per cent) of 27,920 versus 48,623 (27.5 per cent) of 176,749; P = 0.019), underwent minimal access surgery (4565 (16.4 per cent) of 27,920 versus 23,783 (13.5 per cent) of 176,749; P < 0.001) and had surgery for benign diagnoses (6502 (23.3 per cent) of 27,920 versus 38,725 (21.9 per cent) of 176,749; P < 0.001) than those who had surgery on Mondays to Thursdays. In a matched analysis the odds ratio for 30-day mortality after colorectal resections performed on Fridays compared with other weekdays was 1.25 (95 per cent c.i. 1.13 to 1.37); odds ratios for 90-day and 1-year mortality were 1.16 (1.07 to 1.25) and 1.10 (1.04 to 1.16) respectively.

CONCLUSION

Patients selected for colorectal resections on Fridays had a higher mortality rate than patients operated on from Monday to Thursday and had different characteristics, suggesting that increased mortality may reflect patient factors rather than hospital variables alone.

Collective transport properties of driven Skyrmions with random disorder

We use particle-based simulations to examine the static and driven collective phases of Skyrmions interacting with random quenched disorder. We show that nondissipative effects due to the Magnus term reduce the depinning threshold and strongly affect the Skyrmion motion and the nature of the dynamic phases. The quenched disorder causes the Hall angle to become drive dependent in the moving Skyrmion phase, while different flow regimes produce distinct signatures in the transport curves. For weak disorder, the Skyrmions form a pinned crystal and depin elastically, while for strong disorder the system forms a pinned amorphous state that depins plastically. At high drives the Skyrmions can dynamically reorder into a moving crystal, with the onset of reordering determined by the strength of the Magnus term.

Influence of hydrotropic coions on the shape transitions of sodium dioctylsulfosuccinate aggregates in an aqueous medium

The slope change of the CH plot is a manifestation of the shape change of the ionic micelles. However, binding of the salicylate coion to ionic micelles is an exception to this inference.

Structure and interaction in the polymer-dependent reentrant phase behavior of a charged nanoparticle solution

Small-angle neutron scattering (SANS) studies have been carried out to examine the evolution of interaction and structure in a nanoparticle (silica)-polymer (polyethylene glycol) system. The nanoparticle-polymer solution interestingly shows a reentrant phase behavior where the one-phase charged stabilized nanoparticles go through a two-phase system (nanoparticle aggregation) and back to one-phase as a function of polymer concentration. Such phase behavior arises because of the nonadsorption of polymer on nanoparticles and is governed by the interplay of polymer-induced attractive depletion with repulsive nanoparticle-nanoparticle electrostatic and polymer-polymer interactions in different polymer concentration regimes. At low polymer concentrations, the electrostatic repulsion dominates over the depletion attraction. However, the increase in polymer concentration enhances the depletion attraction to give rise to the nanoparticle aggregation in the two-phase system. Further, the polymer-polymer repulsion at high polymer concentrations is believed to be responsible for the reentrance to one-phase behavior. The SANS data in polymer contrast-matched conditions have been modeled by a two-Yukawa potential accounting for both repulsive and attractive parts of total interaction potential between nanoparticles. Both of these interactions (repulsive and attractive) are found to be long range. The magnitude and the range of the depletion interaction increase with the polymer concentration leading to nanoparticle clustering. At higher polymer concentrations, the increased polymer-polymer repulsion reduces the depletion interaction leading to reentrant phase behavior. The nanoparticle clusters in the two-phase system are characterized by the surface fractal with simple cubic packing of nanoparticles within the clusters. The effect of varying ionic strength and polymer size in tuning the interaction has also been examined.

Casimir effect in active matter systems

We numerically examine run-and-tumble active matter particles in Casimir geometries composed of two finite parallel walls. We find that there is an attractive force between the two walls of a magnitude that increases with increasing run length. The attraction exhibits an unusual exponential dependence on the wall separation, and it arises due to a depletion of swimmers in the region between the walls by a combination of the motion of the particles along the walls and a geometric shadowing effect. This attraction is robust as long as the wall length is comparable to or smaller than the swimmer run length, and is only slightly reduced by the inclusion of steric interactions between swimmers. We also examine other geometries and find regimes in which there is a crossover from attraction to repulsion between the walls as a function of wall separation and wall length.

A Theoretical Modeling of the Static and Dynamic Polarizability of O2- in Large and Complex Oxides

A time-dependent approach is employed in conjunction with a crystal potential model to study the environment-specific optical linear response of the O2- ions in a number of cubic oxides with varying number of constituents, unit-cell dimension and degree of complexity. It is shown that the static polarizability of the anion may vary significantly depending on the position of the anion within the unit-cell. Due to neglect of overlap compression, our method has limited success in predicting the refractive indices of large crystals of complex structures. For small binary oxides the frequency-dependent polarizability of the O2- ion is found to exhibit the first poles close to the ultraviolet absorption edges ascribed to the lowest excitonic transitions in these crystals.

Kinetics of heterogeneous reactions of ozone with representative PAHs and an alkene at the air-ice interface at 258 and 188 K

The kinetics of the reaction of an alkene (E-stilbene) and three polycyclic aromatic hydrocarbons (perylene, anthracene and fluoranthene), as examples of environmental pollutants, with ozone on the surface of ice grains (also called "artificial snow"), produced by shock-freezing of aqueous solutions, was studied at submonolayer pollutant coverages (c = 1.5 × 10(-8) to 3 × 10(-10) mol kg(-1)) and two different temperatures (258 and 188 K). This work supports and extends our previous discovery of a remarkable increase in the apparent ozonation rates with decreasing temperature. The ozonation kinetic results were evaluated using the Langmuir-Hinshelwood model and, in one case, the Eley-Rideal kinetic model. It is shown that the apparent rate enhancement is related to the specific nature of the ice surface at different temperatures, which influences the availability of contaminants to gaseous ozone, and to inherent reactivities of the contaminants. The maximum pseudofirst-order rate constants and the lifetimes of the studied compounds are provided. At a typical atmospheric ozone concentration in polar areas (50 ppbv), the lifetimes were estimated to be on the order of hours (258 K) or tens of minutes (188 K) for alkenes, and hundreds (258 K) or tens (188 K) of days for PAHs, thus approximately of the same magnitude or longer than those found for the gas-phase reactions. We imply that this rate enhancement at lower temperatures is a general phenomenon, and we provide data to implement heterogeneous reactions in snow in models that predict the extent of chemical reactions occurring in cold environments.

Transition between mechanisms of laser-induced field-free molecular orientation

The transition between two distinct mechanisms for the laser-induced field-free orientation of CO molecules is observed via measurements of orientation revival times and subsequent comparison to theoretical calculations. In the first mechanism, which we find responsible for the orientation of CO up to peak intensities of 8 × 10(13) W/cm(2), the molecules are impulsively oriented through the hyperpolarizability interaction. At higher intensities, asymmetric depletion through orientation-selective ionization is the dominant orienting mechanism. In addition to the clear identification of the two regimes of orientation, we propose that careful measurements of the onset of the orientation depletion mechanism as a function of the laser intensity will provide a relatively simple route to calibrating absolute rates of nonperturbative strong-field molecular ionization.

Acute kidney injury following unselected emergency admission: role of the inflammatory response, medication and co-morbidity

BACKGROUND/AIMS

Acute kidney injury (AKI) following admission to hospital is associated with increased mortality, morbidity and length of stay. Factors that predispose patients to AKI frequently co-exist. The precise description of their representation in unselected admissions could help define mechanistic inter-relationships and optimise risk stratification strategies. Our aim was therefore to define precisely, using electronically available data, the variables that are associated with AKI.

METHODS

A cohort study of 112,987 emergency admissions to an urban academic medical centre between 2006 and 2010 was performed. Post-admission AKI was defined using KDIGO aligned, proportionate changes in serum creatinine, denominated by the first measured. AKI correlated with co-morbidities, medications received and the C-reactive protein concentration (CRP).

RESULTS

The relationship between post-admission AKI and putative risk factors was defined in univariate and multivariate analyses. Inclusion of CRP in multivariate analyses significantly reduced the strength of association between some co-variables such as radiological contrast and gentamicin administration but not others.

CONCLUSION

The effect of CRP in these analyses supports the role of systemic inflammation in susceptibility to post-admission AKI. It accounts for the greater part of univariate associations between AKI and some nephrotoxic agents, placing the risk attributable to their use in context. Quantification of the systemic inflammatory response may have utility in AKI risk stratification, integrating various determinants of susceptibility.

MEN1 tumorigenesis in the pituitary and pancreatic islet requires Cdk4 but not Cdk2

Recent studies suggest that physiological and tumorigenic proliferation of mammalian cells is controlled by multiple cyclin-dependent kinases (CDKs) largely in tissue-specific manners. We and others previously demonstrated that adult mice deficient for the D-cyclin-dependent kinase CDK4 (Cdk4^−/− mice) exhibit hypoplasia in the pituitary and pancreatic islet due to primary postnatal defects in proliferation. Intriguingly, those neuroendocrine tissues affected in Cdk4^−/− mice are the primary targets of tumorigenesis in the syndrome of multiple endocrine neoplasia type-1 (MEN1). Mice with heterozygous disruption of the tumor suppressor Men1 gene (Men1^+/−) develop tumors in the pituitary, pancreatic islets and other neuroendocrine tissues, which is analogous to humans with MEN1 mutations. To explore the genetic interactions between loss of Men1 and activation of CDKs, we examined the impact of Cdk4 or Cdk2 disruption on tumorigenesis in Men1^+/− mice. A majority of Men1^+/− mice with wild-type CDKs developed pituitary and islet tumors by 15 months of age. Strikingly, Men1^+/−; Cdk4^−/− mice did not develop any tumors, and their islets and pituitaries remained hypoplastic with decreased proliferation. In contrast, Men1^+/−; Cdk2^−/− mice showed pituitary and islet tumorigenesis comparable to those in Men1^+/− mice. Pituitaries of Men1^+/−; Cdk4^−/− mice showed no signs of loss of heterozygosity (LOH) in the Men1 locus, while tumors in Men1^+/− mice and Men1^+/−; Cdk2^−/− mice exhibited LOH. Consistently, CDK4 knockdown in INS-1 insulinoma cells inhibited glucose-stimulated cell cycle progression with a significant decrease in phosphorylation of retinoblastoma protein (RB) at specific sites including Ser780. CDK2 knockdown had minimum effects on RB phosphorylation and cell cycle progression. These data suggest that CDK4 is a critical downstream target of MEN1-dependent tumor suppression and is required for tumorigenic proliferation in the pituitary and pancreatic islet, whereas CDK2 is dispensable for tumorigenesis in these neuroendocrine cell types.