Silicon crystallized in the usual cubic (diamond) lattice structure has dominated the electronics industry for more than half a century. However, cubic silicon (Si), germanium (Ge) and SiGe alloys ...are all indirect-bandgap semiconductors that cannot emit light efficiently. The goal
of achieving efficient light emission from group-IV materials in silicon technology has been elusive for decades
. Here we demonstrate efficient light emission from direct-bandgap hexagonal Ge and SiGe alloys. We measure a sub-nanosecond, temperature-insensitive radiative recombination lifetime and observe an emission yield similar to that of direct-bandgap group-III-V semiconductors. Moreover, we demonstrate that, by controlling the composition of the hexagonal SiGe alloy, the emission wavelength can be continuously tuned over a broad range, while preserving the direct bandgap. Our experimental findings are in excellent quantitative agreement with ab initio theory. Hexagonal SiGe embodies an ideal material system in which to combine electronic and optoelectronic functionalities on a single chip, opening the way towards integrated device concepts and information-processing technologies.
The 2007–2009 human Q fever epidemic in The Netherlands attracted attention due to its magnitude and duration. The current epidemic and the historical background of Q fever in The Netherlands are ...reviewed according to national and international publications. Seroprevalence studies suggest that Q fever was endemic in The Netherlands several decades before the disease was diagnosed in dairy goats and dairy sheep. This was in 2005 and the increase in humans started in 2007. Q fever abortions were registered on 30 dairy goat and dairy sheep farms between 2005 and 2009. A total of 3523 human cases were notified between 2007 and 2009. Proximity to aborting small ruminants and high numbers of susceptible humans are probably the main causes of the human Q fever outbreak in The Netherlands. In general good monitoring and surveillance systems are necessary to assess the real magnitude of Q fever.
Abstract Silicon is indisputably the most advanced material for scalable electronics, but it is a poor choice as a light source for photonic applications, due to its indirect band gap. The recently ...developed hexagonal Si 1− x Ge x semiconductor features a direct bandgap at least for x > 0.65, and the realization of quantum heterostructures would unlock new opportunities for advanced optoelectronic devices based on the SiGe system. Here, we demonstrate the synthesis and characterization of direct bandgap quantum wells realized in the hexagonal Si 1− x Ge x system. Photoluminescence experiments on hex-Ge/Si 0.2 Ge 0.8 quantum wells demonstrate quantum confinement in the hex-Ge segment with type-I band alignment, showing light emission up to room temperature. Moreover, the tuning range of the quantum well emission energy can be extended using hexagonal Si 1− x Ge x /Si 1− y Ge y quantum wells with additional Si in the well. These experimental findings are supported with ab initio bandstructure calculations. A direct bandgap with type-I band alignment is pivotal for the development of novel low-dimensional light emitting devices based on hexagonal Si 1− x Ge x alloys, which have been out of reach for this material system until now.
Background: Chronic stress is often accompanied by alterations in the diurnal rhythm of hypothalamus–pituitary–adrenal activity. However, there are limited data on the diurnal rhythmicity of breast ...milk glucocorticoids (GCs) among women with psychological distress. We compared mothers who sought consultation at an expertise center for pregnant women with an increased risk of psychological distress with control mothers for GC diurnal rhythmicity in milk and saliva obtained at the same time. Methods: We included 19 mothers who sought consultation at the psychiatry–obstetric–pediatric (POP) outpatient clinic and 44 control mothers. One month postpartum, mothers collected on average eight paired milk and saliva samples during a 24 h period. GC levels were measured using liquid chromatography–tandem mass spectrometry. GC rhythmicity parameters were determined with specialized software. Results: For both milk and saliva, no group differences regarding GC rhythms were found. Milk cortisol area under the curve with respect to the ground was lower in the POP group than in the control group (p = 0.02). GC levels in human milk and saliva were highly correlated within each group (p < 0.001). Conclusion: Although there were no differences between groups in GC rhythmicity, the total amount of milk cortisol was lower in the POP group. Long-term follow-up is needed to address the impact of vertical transmission of breast milk GCs.
Background Comprehensive monitoring of colonoscopy quality requires complete and accurate colonoscopy reporting. Objective This study aimed to assess the compliance with colonoscopy reporting and to ...assess the quality of colonoscopy performance. Design Consecutive colonoscopy reports were reviewed by hand. Four hundred reports were included from each department. Setting Daily clinical practice in 12 Dutch endoscopy departments. Patients Consecutive patients undergoing scheduled colonoscopy procedures. Main Outcome Measurements Quality of reporting was assessed by using the American Society for Gastrointestinal Endoscopy criteria for colonoscopy reporting. Quality of colonoscopy performance was evaluated by using the cecal intubation rate and adenoma detection rate (ADR). Results A total of 4800 colonoscopies were performed by 116 endoscopists: 70% by gastroenterologists, 16% by gastroenterology fellows, 10% by internists, 3% by nurse-endoscopists, and 1% by surgeons. The mean age of the patients was 59 years (standard deviation 16), and 47% were male. Reports contained information on indication, sedation practice, and extent of the procedure in more than 90%. Only 62% of the reports mentioned the quality of bowel preparation (range between departments 7%-100%); photographic documentation of the cecal landmarks was present in 71% (range 22%-97%). The adjusted cecal intubation rate was 92% (range 84%-97%). The ADR was 24% (range 13%-32%). Limitations Dependent on reports, no intervention in endoscopic practice. No analysis for performance per endoscopist. Conclusion Colonoscopy reporting varied significantly in clinical practice. Colonoscopy performance met the suggested standards; however, considerable variability between endoscopy departments was found. The results of this study underline the importance of the implementation of quality indicators and guidelines. Moreover, by continuous monitoring of quality parameters, the quality of both colonoscopy reporting and colonoscopy performance can easily be improved.
Clinical efficacy of intravenous immunoglobulin treatment (IVIg) is related to its pharmacokinetic (PK) profile. Its usual evaluation, by measuring serum total IgG levels, is imprecise, because IVIg ...cannot be distinguished from endogenous IgG. We developed ELISAs to specifically monitor the PK of IVIg using the polymorphic determinants G1m(a), G1m(x), and G1m(f). The specificity of the IgG1 allotype assays was sufficient to determine IVIg concentrations as low as 0.1 mg/mL in sera from individuals not expressing the respective markers. IVIg was quantified in posttreatment serum from patients with Guillain–Barré syndrome (GBS) by measuring IgG1 allotypes not expressed endogenously. After serotyping, 27/28 GBS patients were found eligible for IVIg monitoring using one or two genetic markers. In 17 cases, IVIg levels could be determined by both anti‐G1m(a) and anti‐G1m(x) measurement, showing significant correlation. Longitudinal monitoring of IVIg PK in seven GBS patients showed potential differences in clearance of total IgG versus IVIg‐derived IgG, highlighting that total IgG measurements may not accurately reflect IVIg PK. To summarize, anti‐IgG1 allotype assays can discriminate between endogenous IgG and therapeutic polyclonal IgG. These assays will be an important tool to better understand the variability in IVIg PK and treatment response of all patients treated with IVIg.
Clinical efficacy of intravenous immunoglobulin treatment (IVIg) is related to its pharmacokinetic profile, which cannot easily be monitored specifically. We developed assays to specifically monitor the pharmacokinetics of IVIg using polymorphic determinants of IgG1, which allows discrimination between endogenous IgG and therapeutic polyclonal IgG.
The present paper summarises the investigation of two different outbreaks of milk-associated
Campylobacter enteritis in the Netherlands. In 2005, after a school trip to a dairy farm, 22 out of a ...group of 34 children developed diarrhoeal illness and
Campylobacter
jejuni was cultured from the stool samples of 11 of the cases. The illness was found to be epidemiologically associated with drinking raw milk during the farm visit; 86% of the cases could be explained by drinking raw milk.
C.
jejuni was also isolated from three of 10 faecal samples from dairy cattle collected at the farm. The human isolates and
C.
jejuni isolates from one of these three samples of cattle faeces revealed identical restriction patterns by both pulsed-field gel electrophoresis (PFGE) and flagellin (fla) typing by polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP). Both epidemiological and bacteriological evidence implicated contaminated raw milk as the vehicle of transmission, though
C.
jejuni was not isolated from the bulk tank milk or the milk filter collected during the farm investigation. In 2007, an outbreak of enteritis was notified among people who had attended a lunch at a dairy farm where bulk tank milk was served. Of the 19 persons who had consumed raw milk, 16 (84%) had become ill. Of the persons who did not drink the raw milk, none became ill. A significant association was found between tasting the raw milk and being ill (risk difference
=
0.84,
p
=
0.0011).
C.
jejuni was cultured from four of seven cases who had submitted a stool specimen.
C. jejuni was also isolated from a sample of bulk tank milk and the isolate had an identical
flaA PCR–RFLP genotype to isolates obtained from patients. Also in this outbreak both the epidemiological and bacteriological findings support raw milk as the vehicle for the enteritis.
These two outbreaks highlight the health risks associated with the consumption of raw milk. As long as legislation allows the sale and distribution of untreated milk these risks will continue. Therefore, consumers need to be continuously informed about the dangers inherent in consuming unpasteurised milk or products made from raw milk. Farmers need to be strongly discouraged from serving raw milk to their visitors.
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