State-to-state rotational transitions in H2_2+H2_2 collisions at low temperatures

We present quantum mechanical close-coupling calculations of collisions between two hydrogen molecules over a wide range of energies, extending from the ultracold limit to the super-thermal region. The two most recently published potential energy surfaces for the H$_2$-H$_2$ complex, the so-called DJ (Diep and Johnson, 2000) and BMKP (Boothroyd et al., 2002) surfaces, are quantitatively evaluated and compared through the investigation of rotational transitions in H$_2$+H$_2$ collisions within rigid rotor approximation. The BMKP surface is expected to be an improvement, approaching chemical accuracy, over all conformations of the potential energy surface compared to previous calculations of H$_2$-H$_2$ interaction. We found significant differences in rotational excitation/de-excitation cross sections computed on the two surfaces in collisions between two para-H$_2$ molecules. The discrepancy persists over a large range of energies from the ultracold regime to thermal energies and occurs for several low-lying initial rotational levels. Good agreement is found with experiment (Mat\'e et al., 2005) for the lowest rotational excitation process, but only with the use of the DJ potential. Rate coefficients computed with the BMKP potential are an order of magnitude smaller.Comment: Accepted by J. Chem. Phy

WHO Clinical Staging of HIV Infection and Disease, Tuberculosis and Eligibility for Antiretroviral Treatment: Relationship to CD4 Lymphocyte Counts.

SETTING: Thyolo district, Malawi. OBJECTIVES: To determine in HIV-positive individuals aged over 13 years CD4 lymphocyte counts in patients classified as WHO Clinical Stage III and IV and patients with active and previous tuberculosis (TB). DESIGN: Cross-sectional study. METHODS: CD4 lymphocyte counts were determined in all consecutive HIV-positive individuals presenting to the antiretroviral clinic in WHO Stage III and IV. RESULTS: A CD4 lymphocyte count of < or = 350 cells/microl was found in 413 (90%) of 457 individuals in WHO Stage III and IV, 96% of 77 individuals with active TB, 92% of 65 individuals with a history of pulmonary TB (PTB) in the last year, 91% of 89 individuals with a previous history of PTB beyond 1 year, 81% of 32 individuals with a previous history of extra-pulmonary TB, 93% of 107 individuals with active or past TB with another HIV-related disease and 89% of 158 individuals with active or past TB without another HIV-related disease. CONCLUSIONS: In our setting, nine of 10 HIV-positive individuals presenting in WHO Stage III and IV and with active or previous TB have CD4 counts of < or = 350 cells/microl. It would thus be reasonable, in this or similar settings where CD4 counts are unavailable for clinical management, for all such patients to be considered eligible for antiretroviral therapy

A novel strategy for the targeted analysis of protein and peptide metabolites

The detection and quantitation of exogenously administered biological macromolecules (e.g. vaccines, peptide and protein therapeutics) and their metabolites is frequently complicated by the presence of a complex endogenous mixture of closely related compounds. We describe a method that incorporates stable isotope labeling of the compound of interest allowing the selective screening of the intact molecule and all metabolites using a modified precursor ion scan. This method involves monitoring the low molecular weight fragment ions produced during MS/MS that distinguish isotopically labelled material from related endogenous compounds. All isotopically labelled substances can be selected using this scanning technique for further analysis whilst other unlabelled and irrelevant substances are ignored. The potential for this technique to be used in metabolism and pharmacokinetic experiments is discussed with specific examples looking at the metabolism of &#x3b1;-synuclein in serum and the brain

Tunable spin-selective loading of a silicon spin qubit

The remarkable properties of silicon have made it the central material for the fabrication of current microelectronic devices. Silicon's fundamental properties also make it an attractive option for the development of devices for spintronics and quantum information processing. The ability to manipulate and measure spins of single electrons is crucial for these applications. Here we report the manipulation and measurement of a single spin in a quantum dot fabricated in a silicon/silicon-germanium heterostructure. We demonstrate that the rate of loading of electrons into the device can be tuned over an order of magnitude using a gate voltage, that the spin state of the loaded electron depends systematically on the loading voltage level, and that this tunability arises because electron spins can be loaded through excited orbital states of the quantum dot. The longitudinal spin relaxation time T1 is measured using single-shot pulsed techniques and found to be ~3 seconds at a field of 1.85 Tesla. The demonstration of single spin measurement as well as a long spin relaxation time and tunability of the loading are all favorable properties for spintronics and quantum information processing applications.Comment: 4 pages, 3 figures, Supplemental Informatio

Quantum control and process tomography of a semiconductor quantum dot hybrid qubit

The similarities between gated quantum dots and the transistors in modern microelectronics - in fabrication methods, physical structure, and voltage scales for manipulation - have led to great interest in the development of quantum bits (qubits) in semiconductor quantum dots. While quantum dot spin qubits have demonstrated long coherence times, their manipulation is often slower than desired for important future applications, such as factoring. Further, scalability and manufacturability are enhanced when qubits are as simple as possible. Previous work has increased the speed of spin qubit rotations by making use of integrated micromagnets, dynamic pumping of nuclear spins, or the addition of a third quantum dot. Here we demonstrate a new qubit that offers both simplicity - it requires no special preparation and lives in a double quantum dot with no added complexity - and is very fast: we demonstrate full control on the Bloch sphere with $\pi$-rotation times less than 100 ps in two orthogonal directions. We report full process tomography, extracting high fidelities equal to or greater than 85% for X-rotations and 94% for Z-rotations. We discuss a path forward to fidelities better than the threshold for quantum error correction.Comment: 6 pages, excluding Appendi

Probiotics to prevent infantile colic

Background Infantile colic is typically defined as full‐force crying for at least three hours per day, on at least three days per week, for at least three weeks. Infantile colic affects a large number of infants and their families worldwide. Its symptoms are broad and general, and while not indicative of disease, may represent a serious underlying condition in a small percentage of infants who may need a medical assessment. Probiotics are live microorganisms that alter the microflora of the host and provide beneficial health effects. The most common probiotics used are of Lactobacillus, Bifidobacterium and Streptococcus. There is growing evidence to suggest that intestinal flora in colicky infants differ from those in healthy infants, and it is suggested that probiotics can redress this balance and provide a healthier intestinal microbiota landscape. The low cost and easy availability of probiotics makes them a potential prophylactic solution to reduce the incidence and prevalence of infantile colic. Objectives To evaluate the efficacy and safety of prophylactic probiotics in preventing or reducing severity of infantile colic. Search methods In January 2018 we searched CENTRAL, MEDLINE, Embase, PsycINFO, CINAHL, 10 other databases and two trials registers. In addition, we handsearched the abstracts of relevant meetings, searched reference lists, ran citation searches of included studies, and contacted authors and experts in the field, including the manufacturers of probiotics, to identify unpublished trials. Selection criteria Randomised control trials (RCTs) of newborn infants less than one month of age without the diagnosis of infantile colic at recruitment. We included any probiotic, alone or in combination with a prebiotic (also known as synbiotics), versus no intervention, another intervention(s) or placebo, where the focus of the study was the effect of the intervention on infantile colic. Data collection and analysis We used standard methodological procedures of Cochrane. Main results Our search yielded 3284 records, and of these, we selected 21 reports for full‐text review. Six studies with 1886 participants met our inclusion criteria, comparing probiotics with placebo. Two studies examined Lactobacillus reuteri DSM, two examined multi‐strain probiotics, one examined Lactobacillus rhamnosus, and one examined Lactobacillus paracasei and Bifidobacterium animalis. Two studies began probiotics during pregnancy and continued administering them to the baby after birth. We considered the risk of bias for randomisation as low for all six trials; for allocation concealment as low in two studies and unclear in four others. All studies were blinded, and at low risk of attrition and reporting bias. A random‐effects meta‐analysis of three studies (1148 participants) found no difference between the groups in relation to occurrence of new cases of colic: risk ratio (RR) 0.46, 95% confidence interval (CI) 0.18 to 1.19; low‐certainty evidence; I2 = 72%. A random‐effects meta‐analysis of all six studies (1851 participants) found no difference between the groups in relation to serious adverse effects (RR 1.02, 95% CI 0.14 to 7.21; low‐certainty evidence; I2 not calculable (only four serious events for one comparison, two in each group: meconium plug obstruction, patent ductus arteriosus and neonatal hepatitis). A random‐effects meta‐analysis of three studies (707 participants) found a mean difference (MD) of –32.57 minutes per day (95% CI –55.60 to –9.54; low‐certainty evidence; I2 = 93%) in crying time at study end in favour of probiotics. A subgroup analysis of the most studied agent, Lactobacillus reuteri, showed a reduction of 44.26 minutes in daily crying with a random‐effects model (95% CI –66.6 to –21.9; I2 = 92%), in favour of probiotics. Authors' conclusions There is no clear evidence that probiotics are more effective than placebo at preventing infantile colic; however, daily crying time appeared to reduce with probiotic use compared to placebo. There were no clear differences in adverse effects. We are limited in our ability to draw conclusions by the certainty of the evidence, which we assessed as being low across all three outcomes, meaning that we are not confident that these results would not change with the addition of further researc

Cabergoline for suppression of puerperal lactation in a prevention of mother-to-child HIV-transmission programme in rural Malawi.

This study shows that cabergoline (single oral-dose) is an acceptable, safe and effective drug for suppressing puerperal lactation. It could be of operational benefit not only for artificial feeding, but also for weaning in those that breast-feed within preventive mother-to-child HIV transmission programmes in resource-limited settings

Drug resistance degree is associated with duration of ARV exposure and predicted by baseline CD4 and gender in HIV-infected patients failing first-line WHO-recommended ARV regimen: a cross sectional viral load survey of a cohort in Cameroon (Médecins Sans Frontières - Ministry of Health)

Mexico AIDS Conference 200