Thermo-responsive, UV-active poly(phenyl acrylate)-b-poly(diethyl acrylamide) block copolymers

The homopolymerization of phenyl acrylate (PA) was investigated for the first time by nitroxide mediated polymerization (NMP) with the succinimidyl form of the SG1-based unimolecular initiator 2-[N-tert-butyl-2,2-(dimethylpropyl)-aminooxy]propionic acid (BlocBuilder MA). The control of PPA homopolymerization was improved by the use of 15 mol% additional free nitroxide SG1 ([tert-butyl[1-(diethoxyphosphoryl)-2,2-dimethylpropyl]amino]oxidanyl) and dispersities, Mw/Mn, of around 1.2 were achieved. A PPA homopolymer was then successfully chain-extended with diethyl acrylamide (DEAAm) to form a block copolymer of PPA-b-PDEAAm where the PDEAAm segment is thermo-responsive, while the PPA block is potentially UV-active. The thermo-responsive behavior of the block copolymer in 0.5 wt% aqueous solution was studied by UV-Vis spectrometry and dynamic light scattering (DLS), indicating cloud point temperatures of 26–30°C, close to that reported for PDEAAm homopolymers

pB264, a small, mobilizable, temperature sensitive plasmid from Rhodococcus

BACKGROUND: Gram-positive bacteria of the genus Rhodococcus have shown an extraordinary capacity for metabolizing recalcitrant organic compounds. One hindrance to the full exploitation of Rhodococcus is the dearth of genetic tools available for strain manipulation. To address this issue, we sought to develop a plasmid-based system for genetic manipulation of a variety of Rhodococcus strains. RESULTS: We isolated and sequenced pB264, a 4,970 bp cryptic plasmid from Rhodococcus sp. B264-1 with features of a theta-type replication mechanism. pB264 was nearly identical to pKA22, a previously sequenced but uncharacterized cryptic plasmid. Derivatives of pB264 replicate in a diverse range of Rhodococcus species, showing that this plasmid does not bear the same host range restrictions that have been exhibited by other theta replicating plasmids. Replication or maintenance of pB264 is inhibited at 37°C, making pB264 useful as a suicide vector for genetic manipulation of Rhodococcus. A series of deletions revealed that ca. 1.3 kb from pB264 was sufficient to support replication and stable inheritance of the plasmid. This region includes two open reading frames that encode functions (RepAB) that can support replication of pB264 derivatives in trans. Rhodococcus sp. B264-1 will mobilize pB264 into other Rhodococcus species via conjugation, making it possible to genetically modify bacterial strains that are otherwise difficult to transform. The cis-acting element (oriT) required for conjugal transfer of pB264 resides within a ca. 0.7 kb region that is distinct from the regions responsible for replication. CONCLUSION: Shuttle vectors derived from pB264 will be useful for genetic studies and strain improvement in Rhodococcus, and will also be useful for studying the processes of theta replication and conjugal transfer among actinomycetes

Ultrafast Spin Dynamics in Nickel

The spin dynamics in Ni is studied by an exact diagonalization method on the ultrafast time scale. It is shown that the femtosecond relaxation of the magneto-optical response results from exchange interaction and spin-orbit coupling. Each of the two mechanisms affects the relaxation process differently. We find that the intrinsic spin dynamics occurs during about 10 fs while extrinsic effects such as laser-pulse duration and spectral width can slow down the observed dynamics considerably. Thus, our theory indicates that there is still room to accelerate the spin dynamics in experiments.Comment: 4 pages, Latex, 4 postscript figure

Structure and dynamics of the nightside poleward boundary: Sounding rocket and ground-based observations of auroral electron precipitation in a rayed curtain

The Cascades2 auroral sounding rocket provides a case study for comparing multipoint in situ ionospheric observations of a nightside auroral poleward boundary intensification with ground-based optical observations of the same event. Cascades2 was launched northward from Poker Flat Alaska on 20 March 2009 at 11:04 UT. The 13 min flight reached an apogee of 564 km over the northern coast of Alaska. The experiment included a five-payload array of in situ instrumentation, ground cameras at three different points under the trajectory, multiple ground magnetometers, the Poker Flat Incoherent Scatter Radar (PFISR) radar, and the Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft in the magnetotail. The rays of the poleward boundary intensification (PBI) curtain have along-arc motions of 8.5 km/s and along-arc spacings of 16 km. Modulated maximum energy envelopes and energy fluxes of the associated electron precipitation correspond to this spatial structure of the visible rays. The electron precipitation is additionally modulated at a higher frequency, and velocity dispersion analysis of these 8 Hz signatures implies Alfvénic wave-particle acceleration of an ambient ionospheric electron source occurring a few hundred km above the observation point. These observations parameterize the curtain of Alfvénic activity above the PBI event, both in the dispersive ionosphere and in the magnetotail reconnection region. The along-arc variations in brightness correspond to variations in precipitating electron energy flux interpreted as an along-arc modulation of the maximum energy of the Alfvénic wave-particle acceleration process; this is a new interpretation of the formation of rayed structures in auroral curtains. We consider the various possible magnetospheric and ionospheric drivers for the control of the observed along-arc structuring and motions

Near-Infrared Synchrotron Emission from Cas A

High energy observations of Cas A suggested the presence of synchrotron radiation, implying acceleration of cosmic rays by young supernova remnants. We detect synchrotron emission from Cas A in the near-infrared using Two Micron All Sky Survey (2MASS) and Palomar 200 inch PFIRCAM observations. The remnant is detected in J, H, and Ks bands, with Ks band brightest and J faint. In the J and H bands, bright [Fe II] lines (1.24um and 1.64um) are detected spectroscopically. The Palomar observations include Ks continuum, narrow-band 1.64um (centered on [Fe II]) and 2.12um (centered on H2(1-0)) images. While the narrow-band 1.64um image shows filamentary and knotty structures, similar to the optical image, the Ks image shows a relatively smooth, diffuse shell, remarkably similar to the radio image. The broad-band near-infrared fluxes of Cas A are generally consistent with, but a few tens of percent higher than, an extrapolation of the radio fluxes. The hardening to higher frequencies is possibly due to nonlinear shock acceleration and/or spectral index variation across the remnant. We show evidence of spectral index variation. The presence of near-infrared synchrotron radiation requires the roll-off frequency to be higher than 1.5e14 Hz, implying that electrons are accelerated to energies of at least 0.2 TeV. The morphological similarity in diffuse emission between the radio and Ks band images implies that synchrotron losses are not dominant. Our observations show unambiguous evidence that the near-infrared Ks band emission of Cas A is from synchrotron emission by accelerated cosmic-ray electrons.Comment: accepted by Ap

Recent trends in the characteristics and prognosis of patients hospitalized with acute heart failure

BACKGROUND: Despite the magnitude and impact of heart failure (HF) in the United States, relatively little data are available that describe the prognosis associated with acute HF, especially from the perspective of a population-based investigation. The purpose of this nonconcurrent prospective study was to describe the overall, and changing trends therein, prognosis of 4228 patients discharged from all eleven greater Worcester (MA) medical centers after a documented episode of acute HF and factors associated with an increased risk of dying after hospital discharge. METHODS: The study population consisted of residents of the Worcester metropolitan area discharged after being hospitalized for acute HF at all greater Worcester medical centers during 1995 (n = 1783) and 2000 (n = 2445). RESULTS: The 3-month (20% versus 18%), 1-year (41% versus 38%), and 5-year (84% versus 82%) death rates were lower in patients discharged from all metropolitan Worcester hospitals in 2000 versus 1995, respectively. Improving long-term survival rates for patients discharged in 2000 as compared with 1995 were magnified after controlling for several confounding demographic and clinical factors of prognostic importance. A number of potentially modifiable demographic, medical history, and clinical factors were associated with an increased risk of dying during the first year after hospital discharge for acute HF. CONCLUSION: The results of this community-wide observational study suggest improving trends in the long-term prognosis after acute HF. Despite these encouraging trends, the long-term prognosis for patients with acute HF remains poor, and several at-risk groups can be identified for early intervention and increased monitoring efforts

Increase in the proportion of patients hospitalized with acute myocardial infarction with do-not-resuscitate orders already in place between 2001 and 2007: a nonconcurrent prospective study

BACKGROUND AND OBJECTIVE: Shared decision making and advance planning in end-of-life decisions have become increasingly important aspects of the management of seriously ill patients. Here, we describe the use and timing of do-not-resuscitate (DNR) orders in patients hospitalized with acute myocardial infarction (AMI). STUDY DESIGN AND SETTING: The nonconcurrent prospective study population consisted of 4182 patients hospitalized with AMI in central Massachusetts in four annual periods between 2001 and 2007. RESULTS: One-quarter (25%) of patients had a DNR order written either prior to or during hospitalization. The frequency of DNR orders remained constant (24% in 2001; 26% in 2007). Among patients with DNR orders, there was a significant increase in orders written prior to hospitalization (2001: 9%; 2007: 55%). Older patients and those with a medical history of heart failure or myocardial infarction were more likely to have prior DNR orders than respective comparison groups. Patients with prior DNR orders were less likely to die 1 month after hospitalization than patients whose DNRs were written during hospitalization. CONCLUSION: Although the use of DNR orders in patients hospitalized with AMI was stable during the period under study, in more recent years, patients are increasingly being hospitalized with DNR orders already in place