The spin temperature of high-redshift damped Lyman-α\alpha systems

We report results from a programme aimed at investigating the temperature of neutral gas in high-redshift damped Lyman-$\alpha$ absorbers (DLAs). This involved (1) HI 21cm absorption studies of a large DLA sample, (2) VLBI studies to measure the low-frequency quasar core fractions, and (3) optical/ultraviolet spectroscopy to determine DLA metallicities and velocity widths. Including literature data, our sample consists of 37 DLAs with estimates of the spin temperature $T_s$ and the covering factor. We find a strong $4\sigma$) difference between the $T_s$ distributions in high-z (z>2.4) and low-z (z<2.4) DLA samples. The high-z sample contains more systems with high $T_s$ values, $\gtrsim 1000$ K. The $T_s$ distributions in DLAs and the Galaxy are also clearly (~$6\sigma$) different, with more high-$T_s$ sightlines in DLAs than in the Milky Way. The high $T_s$ values in the high-z DLAs of our sample arise due to low fractions of the cold neutral medium. For 29 DLAs with metallicity [Z/H] estimates, we confirm the presence of an anti-correlation between $T_s$ and [Z/H], at $3.5\sigma$ significance via a non-parametric Kendall-tau test. This result was obtained with the assumption that the DLA covering factor is equal to the core fraction. Monte Carlo simulations show that the significance of the result is only marginally decreased if the covering factor and the core fraction are uncorrelated, or if there is a random error in the inferred covering factor. We also find evidence for redshift evolution in DLA $T_s$ values even for the z>1 sub-sample. Since z>1 DLAs have angular diameter distances comparable to or larger than those of the background quasars, they have similar efficiency in covering the quasars. Low covering factors in high-z DLAs thus cannot account for the observed redshift evolution in spin temperatures. (Abstract abridged.)Comment: 37 pages, 22 figures. Accepted for publication in Monthly Notices of the Royal Astronomical Societ

Magnetic states at the surface of alpha Fe2O3 thin films doped with Ti, Zn, or Sn

The spin states at the surface of epitaxial thin films of hematite, both undoped and doped with 1% Ti, Sn or Zn, respectively, were probed with x-ray magnetic linear dichroism (XMLD) spectroscopy. Morin transitions were observed for the undoped (T_M~200 K) and Sn-doped (T_M~300 K) cases, while Zn and Ti-doped samples were always in the high and low temperature phases, respectively. In contrast to what has been reported for bulk hematite doped with the tetravalent ions Sn4+ and Ti4+, for which T_M dramatically decreases, these dopants substantially increase T_M in thin films, far exceeding the bulk values. The normalized Fe LII-edge dichroism for T<T_M does not strongly depend on doping or temperature, except for an apparent increase of the peak amplitudes for T<100 K. We observed magnetic field-induced inversions of the dichroism peaks. By applying a magnetic field of 6.5 T on the Ti-doped sample, a transition into the T>T_M state was achieved. The temperature dependence of the critical field for the Sn-doped sample was characterized in detail. It was demonstrated the sample-to-sample variations of the Fe LIII-edge spectra were, for the most part, determined solely by the spin orientation state. Calculations of the polarization-depedent spectra based on a spin-multiplet model were in reasonable agreement with the experiment and showed a mixed excitation character of the peak structures.Comment: 8 pages, 8 figure

Carbon Nanotubes by a CVD Method. Part I: Synthesis and Characterization of the (Mg, Fe)O Catalysts

The controlled synthesis of carbon nanotubes by chemical vapor deposition requires tailored and wellcharacterized catalyst materials. We attempted to synthesize Mg1-xFexO oxide solid solutions by the combustion route, with the aim of performing a detailed investigation of the influence of the synthesis conditions (nitrate/urea ratio and the iron content) on the valency and distribution of the iron ions and phases. Notably, characterization of the catalyst materials is performed using 57Fe Mo¨ssbauer spectroscopy, X-ray diffraction, and electron microscopy. Several iron species are detected including Fe2+ ions substituting for Mg2+ in the MgO lattice, Fe3+ ions dispersed in the octahedral sites of MgO, different clusters of Fe3+ ions, and MgFe2O4-like nanoparticles. The dispersion of these species and the microstructure of the oxides are discussed. Powders markedly different from one another that may serve as model systems for further study are identified. The formation of carbon nanotubes upon reduction in a H2/CH4 gas atmosphere of the selected powders is reported in a companion paper

Intensity and safety of community-based physical activities for people with COPD

Background: long-term maintenance of the benefits obtained with pulmonary rehabilitation (PR) in people with COPD is of upmost importance, yet highly challenging. Integrating these people in community-based physical activities (PAs), after PR, can be a promising strategy to maintain achieved benefits. Nevertheless, to confidently advise people with COPD to enrol these community-based PAs, clinicians must ensure those are safe and ideally are of at least moderate intensity (following PAs guidelines). This study aimed to explore safety and intensity level of community-based PAs (cardiofitness room, senior gymnastics, and aquatic gymnastics) in people with COPD, after PR. Methods: an observational cross-sectional study, part of a larger trial (NCT04223362) was conducted. People with COPD that had finished a community-based PR programme, conducted in the Respiratory Research and Rehabilitation Laboratory (Lab3R) or in four primary health care centres (Aveiro, Estarreja, Oliveira do Bairro and Montemor-o-Velho), and that had a positive risk-benefit analysis regarding their inclusion on community-based PAs were included. Participants were given the opportunity to choose among the available community-based PAs (previously identified as adequate), the one(s), they wanted to try, and were then accompanied by a physiotherapist. During the community-based PAs, dyspnoea and fatigue perception were assessed every 20 minutes using the modified Borg 0-10 scale; and heart rate (HR) and percentage of peripheral oxygen saturation (SpO2) were constantly monitored. Participants wore the SenseWear Armband on the left triceps to estimate the Metabolic Equivalent Task (METs) of each community-based PA. The final community-based PAs intensity level was obtained by summing the intensity levels yielded by: dyspnoea and fatigue Borg scores, maximal HR percentage predicted (HRmax%predicted) (where HRmaxpredicted=220-age), and METs; with 3-6 Borg scores, 64-76% of HRmax%predicted, and 3-6 METs identifying moderate intensities. For security standards, SpO2 below 88% and HRmax%predicted above 85% were considered. The occurrence of any adverse event during the PAs was registered. Results: three community-based PAs were included, cardiofitness room (9 people with COPD, 68±9 years, 100% men, 58±21 FEV1 %predicted), senior gymnastics (8 people with COPD, 70±9 years, 75% men, 53±11 FEV1 %predicted), and aquatic gymnastics (6 people with COPD, 68±10 years, 100% men, 49±16 FEV1 %predicted). Overall, the explored community-based PAs were classified as of moderate intensity (Figure 1 – a, b, c). Only one participant presented a SpO2 below 88% on the cardiofitness room (lowest SpO2 registered was 86%) and the HRmax%predicted was below 85% in all participants. Mean values of SpO2 and HRmax%predicted are presented in Figure 1 (d, e, f). No adverse event was registered. Conclusion: Cardiofitness room, senior gymnastics, and aquatic gymnastics seem safe and of moderate intensity for people with COPD. Enrolment of people with COPD on these community-based PAs, following PR, should be advised, as these may facilitate the long-term maintenance of PR benefits, while promoting a more physically active lifestyle in this population. Nevertheless, caution is needed when interpreting these results, since intensity of PA is highly influenced by individual factors and patients’ enrolment must be preceded by a careful patient selection to ensure their safety.publishe

Weight loss and clinical characteristics of young adults patients seeking treatment at medical centers: Data from the QUOVADIS Study

OBJECTIVE: To compare clinical characteristics, attrition, weight loss, and psychological changes of obese young adults and obese adults seeking treatment. MATERIALS AND METHODS: 1530 individuals seeking treatment in 18 Italian medical centers were evaluated. 382 cases (25%) were classified as young adults (age≤35 years), 1148 (75%) as adults (>35 years). Psychological distress, binge eating, body uneasiness, and attitude towards eating were evaluated, at baseline and after a 12-month weight-loss program, together with BMI changes. Weight-loss expectations and primary motivation for seeking treatment were also recorded. RESULTS: At baseline, young adults reported significantly higher BMI at age 20, weight loss expectations and body uneasiness scores than adults. A significantly higher percentage of young adults also reported improving appearance as primary reason for seeking treatment. The attrition rate was significantly larger in young adults. Among completers, the mean percent weight loss at 12 months and improvement of psychosocial variables were significantly higher in young adults than in adults. By intention to treat, BMI changes were no longer significant between groups. DISCUSSION: Obese young adults lose more weight and considerably improve psychological distress, but show a higher attrition rate after 12 months of continuous care in a real world medical setting

G0^0 Electronics and Data Acquisition (Forward-Angle Measurements)

The G$^0$ parity-violation experiment at Jefferson Lab (Newport News, VA) is designed to determine the contribution of strange/anti-strange quark pairs to the intrinsic properties of the proton. In the forward-angle part of the experiment, the asymmetry in the cross section was measured for $\vec{e}p$ elastic scattering by counting the recoil protons corresponding to the two beam-helicity states. Due to the high accuracy required on the asymmetry, the G$^0$ experiment was based on a custom experimental setup with its own associated electronics and data acquisition (DAQ) system. Highly specialized time-encoding electronics provided time-of-flight spectra for each detector for each helicity state. More conventional electronics was used for monitoring (mainly FastBus). The time-encoding electronics and the DAQ system have been designed to handle events at a mean rate of 2 MHz per detector with low deadtime and to minimize helicity-correlated systematic errors. In this paper, we outline the general architecture and the main features of the electronics and the DAQ system dedicated to G$^0$ forward-angle measurements.Comment: 35 pages. 17 figures. This article is to be submitted to NIM section A. It has been written with Latex using \documentclass{elsart}. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment In Press (2007

Evidence for Quantum Interference in SAMs of Arylethynylene Thiolates in Tunneling Junctions with Eutectic Ga-In (EGaIn) Top-Contacts

This paper compares the current density (J) versus applied bias (V) of self-assembled monolayers (SAMs) of three different ethynylthiophenol-functionalized anthracene derivatives of approximately the same thickness with linear-conjugation (AC), cross-conjugation (AQ), and broken-conjugation (AH) using liquid eutectic Ga-In (EGaIn) supporting a native skin (~1 nm thick) of Ga2O3 as a nondamaging, conformal top-contact. This skin imparts non-Newtonian rheological properties that distinguish EGaIn from other top-contacts; however, it may also have limited the maximum values of J observed for AC. The measured values of J for AH and AQ are not significantly different (J ≈ 10-1 A/cm2 at V = 0.4 V). For AC, however, J is 1 (using log averages) or 2 (using Gaussian fits) orders of magnitude higher than for AH and AQ. These values are in good qualitative agreement with gDFTB calculations on single AC, AQ, and AH molecules chemisorbed between Au contacts that predict currents, I, that are 2 orders of magnitude higher for AC than for AH at 0 < |V| < 0.4 V. The calculations predict a higher value of I for AQ than for AH; however, the magnitude is highly dependent on the position of the Fermi energy, which cannot be calculated precisely. In this sense, the theoretical predictions and experimental conclusions agree that linearly conjugated AC is significantly more conductive than either cross-conjugated AQ or broken conjugate AH and that AQ and AH cannot necessarily be easily differentiated from each other. These observations are ascribed to quantum interference effects. The agreement between the theoretical predictions on single molecules and the measurements on SAMs suggest that molecule-molecule interactions do not play a significant role in the transport properties of AC, AQ, and AH.

Impact of pulmonary rehabilitation on the social support of people with COPD

Social support improves general health (e.g., reduces hospitalisations and exacerbations) and well-being of people with COPD, but it has shown to be low in this population. Pulmonary rehabilitation (PR) has potential to improve social support of people with COPD, however, this needs to be investigated. This study explored the impacts of PR on the social support of people with COPD. An observational study was conducted. Participants received community-based PR for 3 months, twice a week. Sociodemographic and lung function data were used to characterise the sample. Quantity and quality of social support were assessed with the 6-item short form Social Support Questionnaire (SSQ). For each item, participants listed all people or institutions who support them on a certain situation (range: 0-9 people; quantity) and indicated how satisfied they were with the support provided (range: 1 very dissatisfied to 6 very satisfied; quality). Total score for quantity and quality was computed using the mean scores from the 6 items. Frequencies, median and interquartile range (IQR) were used to describe the sample. Wilcoxon test was used to explore pre-post differences. Twenty-nine people with COPD (71 [65-77] years; 86.2% ♂; 54 [39.4-62.5] FEV1%pp) participated. No significant impacts were found for quantity (pre 1.5 [1-3.2] vs post 1.7 [1-2.2], p=0.135) nor quality (pre 6 [5.7-6] vs post 6 [5.4-6], p=0.299) of social support after PR. A ceiling effect seem to exist on quality. PR seems to yield minimal impact on the social support of people with COPD assessed with the SSQ. Future work on how to improve social support of people with COPD is needed (e.g., identify determinants and social responses).publishe