Noise-free high-efficiency photon-number-resolving detectors

High-efficiency optical detectors that can determine the number of photons in a pulse of monochromatic light have applications in a variety of physics studies, including post-selection-based entanglement protocols for linear optics quantum computing and experiments that simultaneously close the detection and communication loopholes of Bell's inequalities. Here we report on our demonstration of fiber-coupled, noise-free, photon-number-resolving transition-edge sensors with 88% efficiency at 1550 nm. The efficiency of these sensors could be made even higher at any wavelength in the visible and near-infrared spectrum without resulting in a higher dark-count rate or degraded photon-number resolution.Comment: 4 pages, 4 figures Published in Physical Review A, Rapid Communications, 17 June 200

Party On: The Labor Market Returns to Social Networks in Adolescence

We investigate the returns to adolescent friendships on earnings in adulthood. Using data from the National Longitudinal Study of Adolescent to Adult Health, we document that individuals make investments to accumulate friends in addition to educational investments. Because both education and friendships are jointly determined in adolescence, OLS estimates of their returns are biased. To estimate the causal returns to friendships, we implement a novel procedure that assumes the returns to schooling range from 5 to 15% (as the literature has documented), and instrument for friendships using homophily (similarity) measures among peers to obtain bounds on the returns to friendships. We find that having one more friend in adolescence increases earnings between 7 and 14%, which is substantially larger than the OLS estimates: measurement error and omitted variables lead to significant downward bias

Coliphages of the human urinary microbiota

Due to its frequent association with urinary tract infections (UTIs), Escherichia coli is the best characterized constituent of the urinary microbiota (urobiome). However, uropathogenic E. coli is just one member of the urobiome. In addition to bacterial constituents, the urobiome of both healthy and symptomatic individuals is home to a diverse population of bacterial viruses (bacteriophages). A prior investigation found that most bacterial species in the urobiome are lysogens, harboring one or more phages integrated into their genome (prophages). Many of these prophages are temperate phages, capable of entering the lytic cycle and thus lysing their bacterial host. This transition from the lysogenic to lytic life cycle can impact the bacterial diversity of the urobiome. While many phages that infect E. coli (coliphages) have been studied for decades in the laboratory setting, the coliphages within the urobiome have yet to be cataloged. Here, we investigated the diversity of urinary coliphages by first identifying prophages in all publicly available urinary E. coli genomes. We detected 3,038 intact prophage sequences, representative of 1,542 unique phages. These phages include both novel species as well as species also found within the gut microbiota. Ten temperate phages were isolated from urinary E. coli strains included in our analysis, and we assessed their ability to infect and lyse urinary E. coli strains. We also included in these host range assays other urinary coliphages and laboratory coliphages. The temperate phages and other urinary coliphages were successful in lysing urinary E. coli strains. We also observed that coliphages from non-urinary sources were most efficient in killing urinary E. coli strains. The two phages, T2 and N4, were capable of lysing 83.5% (n = 86) of strains isolated from females with UTI symptoms. In conclusion, our study finds a diverse community of coliphages in the urobiome, many of which are predicted to be temperate phages, ten of which were confirmed here. Their ability to infect and lyse urinary E. coli strains suggests that urinary coliphages may play a role in modulating the E. coli strain diversity of the urobiome

Examination of staphylococcus aureus prophages circulating in Egypt

Staphylococcus aureus infections are of growing concern given the increased incidence of antibiotic resistant strains. Egypt, like several other countries, has seen alarming increases in methicillin-resistant S. aureus (MRSA) infections. This species can rapidly acquire genes associated with resistance, as well as virulence factors, through mobile genetic elements, including phages. Re-cently, we sequenced 56 S. aureus genomes from Alexandria Main University Hospital in Alexandria, Egypt, complementing 17 S. aureus genomes publicly available from other sites in Egypt. In the current study, we found that the majority (73.6%) of these strains contain intact prophages, including Biseptimaviruses, Phietaviruses, and Triaviruses. Further investigation of these prophages revealed evidence of horizontal exchange of the integrase for two of the prophages. These Egyptian S. aureus prophages are predicted to encode numerous virulence factors, including genes associated with immune evasion and toxins, including the Panton–Valentine leukocidin (PVL)-associated genes lukF-PV/lukS-PV. Thus, prophages are likely to be a major contributor to the virulence of S. aureus strains in circulation in Egypt

Implementación de un prototipo mecánico para medir la resistencia a la rotura de la flor de cuero (Lastómetro)

En las instalaciones de la Constructora “Velásquez e hijos se realizó el diseño y construcción del prototipo mecánico lastómetro, para su validación se realizó pruebas tanto en el Laboratorio de Control de calidad de ANCE como en la ESPOCH, que se constituyeron las unidades experimentales y los resultados adquiridos fueron comparados utilizando una estadística descriptiva para determinar si existen o no diferencias entre laboratorios. Por lo tanto se afirma que para la construcción e implementación del prototipo mecánico, se utilizó materiales de primera calidad, para asegurar la precisión en el ensayo así como para la aplicación de la técnica de manufactura y el cálculo de la potencia del equipo que fue de 559,25 watts, ya que la eficiencia del equipo fue igual a 75%. En la evaluación de las resistencias físicas del cuero se determinó que al curtir las pieles se obtienen mayores resultados de espesor del cuero (1,12 mm), y lastrometría 10,06 mm, mientras tanto que la mayor resistencia a la tensión (1809,83 N/cm2), y porcentaje de elongación (62,50%), se registró al curtir las pieles al vegetal. Se afirma que la construcción e implementación del equipo mantuvo un protocolo de producción de primera calidad que resulta competitiva para la industria nacional. Los costos de producción al reportar un valor de 3177 dólares americanos, son inferiores a los registrados en preformas tanto nacionales como internacionales que determinan un precio de venta de 10000 dólares por lo que representa una disminución considerable en la manufactura, y con resultados de precisión satisfactoria.At ¨ Velasquez and children¨ construction company, it was developed the desing and construction of a mechanical prototype lastometry, for its validation some tests were developed either at the Laboratory of quality control from the ANCE as in ESPOCH which constituted the experimental units and the results obtained were compared using descriptive statistics in order to determine if there are any differences between laboratories. For instance, it is said that for the construction and implementation of the mechanical prototype, high quality materials were used in order to make sure the precision in the essay as well as the application of the manufacturing technique and the equipment power record was 559,25 watts, since the efficiency of the machine was 80%. In the evaluation of physical resistance of the leather, it was determined that when tanning the fur, the thickness of the leather is better (1,12mm), lastometry (10,06 mm) and time for breakage (1,01 s) which was obtained when tanning leather with chrome meanwhile the highest resistance to tension is (1809,83 N/cm2) and a percentage of lengthen (62,50 %) was registered when tanning leather with vegetables. It is claimed that the construction and implementation of the equipment kept a high quality protocol which is competitive for national industry. The production costs of over 3117 American dollars are lower to those registered in the national and international budgets which state a price of 10000 dollars, this represents a meaningful reduction in manufacturing and satisfactory precision results