Highly site-specific H2 adsorption on vicinal Si(001) surfaces

Experimental and theoretical results for the dissociative adsorption of H_2 on vicinal Si(001) surfaces are presented. Using optical second-harmonic generation, sticking probabilities at the step sites are found to exceed those on the terraces by up to six orders of magnitude. Density functional theory calculations indicate the presence of direct adsorption pathways for monohydride formation but with a dramatically lowered barrier for step adsorption due to an efficient rehybridization of dangling orbitals.Comment: 5 pages, 4 figures, submitted to Phys. Rev. Lett. (1998). Other related publications can be found at http://www.fhi-berlin.mpg.de/th/paper.htm

Carbapenem Resistance in Klebsiella pneumoniae Not Detected by Automated Susceptibility Testing

Detecting β-lactamase–mediated carbapenem resistance among Klebsiella pneumoniae isolates and other Enterobacteriaceae is an emerging problem. In this study, 15 blaKPC-positive Klebsiella pneumoniae that showed discrepant results for imipenem and meropenem from 4 New York City hospitals were characterized by isoelectric focusing; broth microdilution (BMD); disk diffusion (DD); and MicroScan, Phoenix, Sensititre, VITEK, and VITEK 2 automated systems. All 15 isolates were either intermediate or resistant to imipenem and meropenem by BMD; 1 was susceptible to imipenem by DD. MicroScan and Phoenix reported 1 (6.7%) and 2 (13.3%) isolates, respectively, as imipenem susceptible. VITEK and VITEK 2 reported 10 (67%) and 5 (33%) isolates, respectively, as imipenem susceptible. By Sensititre, 13 (87%) isolates were susceptible to imipenem, and 12 (80%) were susceptible to meropenem. The VITEK 2 Advanced Expert System changed 2 imipenem MIC results from >16 μg/mL to <2 μg/mL but kept the interpretation as resistant. The recognition of carbapenem-resistant K. pneumoniae continues to challenge automated susceptibility systems

Density-functional study of hydrogen chemisorption on vicinal Si(001) surfaces

Relaxed atomic geometries and chemisorption energies have been calculated for the dissociative adsorption of molecular hydrogen on vicinal Si(001) surfaces. We employ density-functional theory, together with a pseudopotential for Si, and apply the generalized gradient approximation by Perdew and Wang to the exchange-correlation functional. We find the double-atomic-height rebonded D_B step, which is known to be stable on the clean surface, to remain stable on partially hydrogen-covered surfaces. The H atoms preferentially bind to the Si atoms at the rebonded step edge, with a chemisorption energy difference with respect to the terrace sites of >sim 0.1 eV. A surface with rebonded single atomic height S_A and S_B steps gives very similar results. The interaction between H-Si-Si-H mono-hydride units is shown to be unimportant for the calculation of the step-edge hydrogen-occupation. Our results confirm the interpretation and results of the recent H_2 adsorption experiments on vicinal Si surfaces by Raschke and Hoefer described in the preceding paper.Comment: 13 pages, 8 figures, submitted to Phys. Rev. B. Other related publications can be found at http://www.rz-berlin.mpg.de/th/paper.htm

Normal microRNA Maturation and Germ-Line Stem Cell Maintenance Requires Loquacious, a Double-Stranded RNA-Binding Domain Protein

microRNAs (miRNAs) are single-stranded, 21- to 23-nucleotide cellular RNAs that control the expression of cognate target genes. Primary miRNA (pri-miRNA) transcripts are transformed to mature miRNA by the successive actions of two RNase III endonucleases. Drosha converts pri-miRNA transcripts to precursor miRNA (pre-miRNA); Dicer, in turn, converts pre-miRNA to mature miRNA. Here, we show that normal processing of Drosophila pre-miRNAs by Dicer-1 requires the double-stranded RNA-binding domain (dsRBD) protein Loquacious (Loqs), a homolog of human TRBP, a protein first identified as binding the HIV trans-activator RNA (TAR). Efficient miRNA-directed silencing of a reporter transgene, complete repression of white by a dsRNA trigger, and silencing of the endogenous Stellate locus by Suppressor of Stellate, all require Loqs. In loqs (f00791) mutant ovaries, germ-line stem cells are not appropriately maintained. Loqs associates with Dcr-1, the Drosophila RNase III enzyme that processes pre-miRNA into mature miRNA. Thus, every known Drosophila RNase-III endonuclease is paired with a dsRBD protein that facilitates its function in small RNA biogenesis

Limited Vitrectomy versus Complete Vitrectomy for Epiretinal Membranes: A Comparative Multicenter Trial

Purpose. To evaluate whether limited vitrectomy is as effective as complete vitrectomy in eyes with epiretinal membrane (ERM) and to compare the surgical times and rates of complications. Methods. In this multicentre European study, data of eyes with ERM that underwent vitrectomy from January 2017 to July 2018 were analyzed retrospectively. In the limited vitrectomy group, a posterior vitreous detachment (PVD) was induced up till the equator as opposed to complete PVD induction till the vitreous base in the comparison group. Incidence of iatrogenic retinal breaks, retinal detachment, surgical time, and visual outcomes were compared between groups. Results. We included 139 eyes in the analysis with a mean age being 72.2 \ub1 6.9 years. In this, sixty-five eyes (47%) underwent limited vitrectomy and 74 eyes (53%) underwent complete vitrectomy. Iatrogenic retinal tears were seen in both groups (5% in limited vitrectomy versus 7% in complete vitrectomy, p=0.49). Retinal detachment occurred in 2 eyes in the limited vitrectomy group (3%) compared to none in the complete vitrectomy group (p=0.22). Best-corrected visual acuity (BCVA) and central macular thickness improved significantly with no intergroup differences (p=0.18). Surgical time was significantly shorter in the limited vitrectomy group with 91% surgeries taking less than 1 hour compared to 71% in the complete vitrectomy group (p&lt;0.001). Conclusion. A limited vitrectomy is a time-efficient and effective surgical procedure for removal of epiretinal membrane with no additional complications

Investigating the impact of poverty on colonization and infection with drug-resistant organisms in humans: a systematic review

Background Poverty increases the risk of contracting infectious diseases and therefore exposure to antibiotics. Yet there is lacking evidence on the relationship between income and non-income dimensions of poverty and antimicrobial resistance. Investigating such relationship would strengthen antimicrobial stewardship interventions. Methods A systematic review was conducted following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. PubMed, Ovid, MEDLINE, EMBASE, Scopus, CINAHL, PsychINFO, EBSCO, HMIC, and Web of Science databases were searched in October 2016. Prospective and retrospective studies reporting on income or non-income dimensions of poverty and their influence on colonisation or infection with antimicrobial-resistant organisms were retrieved. Study quality was assessed with the Integrated quality criteria for review of multiple study designs (ICROMS) tool. Results Nineteen articles were reviewed. Crowding and homelessness were associated with antimicrobial resistance in community and hospital patients. In high-income countries, low income was associated with Streptococcus pneumoniae and Acinetobacter baumannii resistance and a seven-fold higher infection rate. In low-income countries the findings on this relation were contradictory. Lack of education was linked to resistant S. pneumoniae and Escherichia coli. Two papers explored the relation between water and sanitation and antimicrobial resistance in low-income settings. Conclusions Despite methodological limitations, the results suggest that addressing social determinants of poverty worldwide remains a crucial yet neglected step towards preventing antimicrobial resistance

Studiul combaterii biologice a tripsului comun la ardei

The trials of tripsattack and ecological control of pests were performed at Vegetable Research and Development Station Bacau –Romania, during 2016 -2017. The dynamic of trips attack in pepperand effectiveness of Amblyseius swirskii At.-H. (Arachnida, Mesostigmata, Phytoseiidae) releases in control of onion tripsat pepper collection of cultivars in tunnelswasstudied. The trial of A. swirskii in tripscontrol was performed at the followingrelease rates: V1 –500,000 mites/ha; V2 –700,000 mites/ha; V3 –900,000 mites/ha; V4. 1 million mites/ha; V5 -Control.On observed that the reducing trips degree attack by release of A. swirskii at pepper is effective in August -September usingthe release rates between 700,000 ex /ha -1,000,000 ex/ ha

Tigecycline use in serious nosocomial infections: a drug use evaluation

<p>Abstract</p> <p>Background</p> <p>Tigecycline is a novel antibiotic with activity against multidrug resistant bacteria. The aim of this study was to assess the efficacy of tigecycline use in serious hospital-acquired infections (HAI)</p> <p>Case presentation</p> <p>Prospective observational study of tigecycline use was conducted in a 1500 beds university hospital. From January 1, 2007 and January 31, 2010, 207 pts were treated with tigecycline for the following indications: intra-abdominal, pneumonia, bloodstream and complicated skin and soft tissue infections and febrile neutropenia. The therapy was targeted in 130/207 (63%) and empirical in 77/207 (37%) patients. All bacteria treated were susceptible to tigecycline. Median duration of tigecycline therapy was 13 days (range, 6-28). Clinical success was obtained in 151/207 (73%) cases, with the highest success rate recorded in intra-abdominal infections [81/99 (82%)]. Microbiological success was achieved in 100/129 (78%) treated patients. Adverse clinical events were seen in 16/207 patients (7.7%):</p> <p>Conclusions</p> <p>Considering the lack of data on tigecycline for critically ill patients, we think that the reported data of our clinical experience despite some limitations can be useful for clinicians.</p