Influence of structure on the optical limiting properties of nanotubes

We investigate the role of carbon nanotubes structure on their optical limiting properties. Samples of different and well-characterized structural features are studied by optical limiting and pump-probe experiments. The influence of the diameter's size on the nano-object is demonstrated. Indeed, both nucleation and growth of gas bubbles are expected to be sensitive to diameter

Public Sector Leaders\u27 Strategies to Improve Employee Retention

The U.S. Department of Labor and Statistics consistently reports significant employee turnover in the public sector, including the federal, state, and local levels. High turnover results in compromised public goods and services provided to a community. The widespread nature of the problem and the scarcity of literature focusing on employee retention strategies in the public sector merited this case study. Public sector leaders from Western New York who had implemented employee retention strategies in a public organization comprised the population for the study. Cost-benefit theory, human capital theory, and social capital theory provided the conceptual context for developing and executing the study. A total of 7 public sector leaders participated in semistructured interviews, which provided the primary source of data. Data were open coded, resulting in themes of employee development, engagement and empowerment, and positive work experience. The results contribute to social change by identifying practical business strategies that leaders may use to improve retention in their respective organizations. Maintaining a well-qualified, dedicated public workforce may lead to improved government goods and services on which communities rely

Combination of carbon nanotubes and two-photon absorbers for broadband optical limiting

New systems are required for optical limiting against broadband laser pulses. We demonstrate that the association of non-linear scattering from single-wall carbon nanotubes (SWNT) and multiphoton absorption (MPA) from organic chromophores is a promising approach to extend performances of optical limiters over broad spectral and temporal ranges. Such composites display high linear transmission and good neutral colorimetry and are particularly efficient in the nanosecond regime due to cumulative effects.Comment: 5 avril 200

Recognizing Emotions in a Foreign Language

Expressions of basic emotions (joy, sadness, anger, fear, disgust) can be recognized pan-culturally from the face and it is assumed that these emotions can be recognized from a speaker's voice, regardless of an individual's culture or linguistic ability. Here, we compared how monolingual speakers of Argentine Spanish recognize basic emotions from pseudo-utterances ("nonsense speech") produced in their native language and in three foreign languages (English, German, Arabic). Results indicated that vocal expressions of basic emotions could be decoded in each language condition at accuracy levels exceeding chance, although Spanish listeners performed significantly better overall in their native language ("in-group advantage"). Our findings argue that the ability to understand vocally-expressed emotions in speech is partly independent of linguistic ability and involves universal principles, although this ability is also shaped by linguistic and cultural variables

Cryo-Electron Tomography Elucidates the Molecular Architecture of Treponema pallidum, the Syphilis Spirochete

Cryo-electron tomography (CET) was used to examine the native cellular organization of Treponema pallidum, the syphilis spirochete. T. pallidum cells appeared to form flat waves, did not contain an outer coat and, except for bulges over the basal bodies and widening in the vicinity of flagellar filaments, displayed a uniform periplasmic space. Although the outer membrane (OM) generally was smooth in contour, OM extrusions and blebs frequently were observed, highlighting the structure’s fluidity and lack of attachment to underlying periplasmic constituents. Cytoplasmic filaments converged from their attachment points opposite the basal bodies to form arrays that ran roughly parallel to the flagellar filaments along the inner surface of the cytoplasmic membrane (CM). Motile treponemes stably attached to rabbit epithelial cells predominantly via their tips. CET revealed that T. pallidum cell ends have a complex morphology and assume at least four distinct morphotypes. Images of dividing treponemes and organisms shedding cell envelope-derived blebs provided evidence for the spirochete’s complex membrane biology. In the regions without flagellar filaments, peptidoglycan (PG) was visualized as a thin layer that divided the periplasmic space into zones of higher and lower electron densities adjacent to the CM and OM, respectively. Flagellar filaments were observed overlying the PG layer, while image modeling placed the PG-basal body contact site in the vicinity of the stator–P-collar junction. Bioinformatics and homology modeling indicated that the MotB proteins of T. pallidum, Treponema denticola, and Borrelia burgdorferi have membrane topologies and PG binding sites highly similar to those of their well-characterized Escherichia coli and Helicobacter pylori orthologs. Collectively, our results help to clarify fundamental differences in cell envelope ultrastructure between spirochetes and gram-negative bacteria. They also confirm that PG stabilizes the flagellar motor and enable us to propose that in most spirochetes motility results from rotation of the flagellar filaments against the PG

Geología y mineralogía del yacimiento polimetálico de Au-As (Ag-Pb-Zn-Cu-Sb) de Valiña-Azúmara (Lugo, NO de España)

Valiña-Azúmara is a polymetallic Au-As (Ag-Pb-Zn-Cu-Sb) deposit, located in the province of Lugo (NW Spain), that was mined for arsenic at the beginning of the 20th century. The mineralization is hosted in a Variscan thrust fault with a dip direction of N247-261ºE, and N-S and NE-SW Late-Variscan faults. These structures are hosted in black slates, Cambrian in age. To a lesser extent, the mineralization also occurs disseminated within narrow, weakly silicified and sericited selvages. Mineralization is divided into two hypogene stages. The first consists of quartz, calcite, rutile, sericite, arsenopyrite and pyrite. Two types of pyrite (Py-I and Py-II) are defined according to their chemical and textural characteristics. Py-II occurs as overgrowth of previous Py-I crystals. Py-II is As-rich (≤1.7 wt.%) and often contains traces of Te, Zn, Cu, Bi, Sb and Au. The mineralized drill core sections show a significant correlation between Au and As. This is due to Au occurring as invisible Au within the Py-II grains, with contents of up to 176 ppm. The Au/As ratios of Py-II indicate that Au was deposited as Au1+, as solid solution within the pyrite structure. The second stage of mineralization is enriched in Ag-Pb-Zn-Cu-Sb, replacing the first stage, and consists of quartz, calcite, chlorite, sphalerite, jamesonite, Ag-rich tetrahedrite, freibergite, chalcopyrite, pyrrhotite and galena. Although jamesonite shows traces of Ag, the Cu-Ag sulfosalts are the main carriers of the Ag mineralization in the deposit, with contents that vary from 13.7 to 23.9 wt.% of Ag. In the most superficial levels of the area, secondary Fe oxide and hydroxide, scorodite and anglesite developed due to the oxidation of the ore.Valiña-Azúmara es un yacimiento filoniano de Au-As (Ag-Pb-Zn-Cu-Sb) situado en la provincia de Lugo (NO España), que fue explotado por arsénico a principios del siglo XX. La mineralización se encuentra encajada en un cabalgamiento Varisco de dirección de buzamiento N247-261°E y en fracturas tardivariscas de dirección N-S y NE-SO que cortan a filitas negras de edad Cámbrica. En menor medida la mineralización también se encuentra diseminada en el encajante, en finas salbandas levemente sericitizadas y silicificadas. La mineralización se divide en dos etapas hipogénicas. La primera está constituida por cuarzo, calcita, rutilo, sericita, arsenopirita y pirita. En base a su composición y textura, se diferencian dos tipos de pirita, Py-I y Py II. La Py-II suele encontrarse recrecida sobre la Py I, formando bandas poligonales. Esta pirita está enriquecida en As (≤1,7% en peso) y contiene trazas de otros metales como Te, Zn, Cu, Bi, Sb y Au. Los tramos mineralizados de sondeo del yacimiento presentan correlación geoquímica entre los elementos Au y As, debido a que el Au se halla en forma de oro refractario dentro de los cristales de pirita arsenical (Py-II), los cuales llegan a presentar concentraciones en Au de hasta 176 ppm. La relación Au/As de la Py-II sugiere que el oro se encuentra en forma de Au+1, en solución sólida dentro de la estructura cristalina del mineral. La segunda etapa de mineralización está enriquecida en Ag-Pb-Zn-Cu-Sb y consiste en cuarzo, calcita, clorita, esfalerita, jamesonita, cobres grises (tetraedrita argentífera y freibergita), calcopirita, pirrotina y galena. Esta etapa se encuentra rellenando fracturas y cavidades intersticiales en los minerales de la etapa anterior, reemplazándolos en parte. Los principales minerales portadores de Ag son los cobres grises, con contenidos que varían entre 13,7 y 23,9% en peso. En la parte más superficial del yacimiento, la alteración supergénica de la mena primaria dio como resultado la formación de óxidos e hidróxidos de hierro, escorodita y anglesita

EUS assessment for intermediate risk of choledocholithiasis after a negative magnetic resonance cholangiopancreatography

© 2020 SPRING MEDIA PUBLISHING CO. LTD | PUBLISHED BY WOLTERS KLUWER - MEDKNOW 291. Background and Aims: Guidelines recommend either EUS or magnetic resonance cholangiopancreatography (MRCP) for intermediate risk of choledocholithiasis. There is a lack of evidence that supports proceeding with EUS if the MRCP is negative and if clinical suspicion still exists. Methods: This is a retrospective study of all patients who underwent EUS to assess for choledocholithiasis at a tertiary care referral center from July 2013 to October 2019. Results: A total of 593 patients underwent EUS for evaluation for choledocholithiasis. Of the 593 patients, 35.2% (209/593) had an MRCP. 73.2% (153/209) had a negative MRCP while 26.8% (56/209) had a positive MRCP. Of the group of patients who underwent EUS with a negative MRCP, 15% (23/153) were positive for choledocholithiasis on EUS. Of these, 91% (21/23) were also positive for sludge or stones on endoscopic retrograde cholangiopancreatography and thus 14% (21/153) of the EUS were \u27true positives.\u27 There were no clinical or laboratory factors predictive of choledocholithiasis on univariate analysis in the EUS plus negative MRCP group. When further analyzing the MRCP negative group into MRCP-/EUS+ and MRCP-/EUS-subgroups, a total bilirubin \u3e3 mg/dL predicted a bile duct stone (55% vs. 32%, P = 0.05). Conclusion: The diagnostic yield of EUS for suspected choledocholithiasis in the setting of a negative MRCP is 14% in our cohort. EUS should be considered in patients with intermediate risk of choledocholithiasis with a negative MRCP if the clinical suspicion is still present, and especially if the total bilirubin is above 3 mg/dL

Force and acceleration characteristics of military foot drill: implications for injury risk in recruits

Background: Foot drill involving marching and drill manoeuvres is conducted regularly during basic military recruit training. Characterising the biomechanical loading of foot drill will improve our understanding of the contributory factors to lower limb overuse injuries in recruits. Aim: Quantify and compare forces, loading rates and accelerations of British Army foot drill, within and between trained and untrained personnel. Methods: 24 trained soldiers (12 men and 12 women; TRAINED) and 12 civilian men (UNTRAINED) performed marching and five drill manoeuvres on force platforms; motion capture recorded tibial position. Peak vertical impact force (PF), peak vertical loading rate (PLR), expressed as multiples of body weight (BW) and peak tibial impact acceleration (PTA) were recorded. Results: Drill manoeuvre PF, PLR and PTA were similar, but higher in TRAINED men (PF, PLR: p<0.01; PTA: p<0.05). Peak values in TRAINED men were shown for the halt (mean (SD); PF: 6.5 (1.5) BW; PLR: 983 (333) BW/s PTA; PTA: 207 (57) m/s2) and left turn (PF: 6.6 (1.7) BW; PLR: 928 (300) BW/s; 184 (62) m/s2). Marching PF, PLR, PTA were similar between groups and lower than all drill manoeuvres (PF: 1.1–1.3 BW; PLR: 42–70 BW/s; p<0.01; PTA: 23–38 m/s2; p<0.05). Conclusions: Army foot drill generates higher forces, loading rates and accelerations than activities such as running and load carriage, while marching is comparable to moderate running (10.8 km/h). The large biomechanical loading of foot drill may contribute to the high rate of overuse injuries during initial military training, and strategies to regulate/reduce this loading should be explored

Dietary Intake and Nitrogen Balance in British Army Infantry Recruits Undergoing Basic Training

We assessed dietary intake and nitrogen balance during 14 weeks of Basic Training (BT) in British Army Infantry recruits. Nineteen men (mean ± SD: age 19.9 ± 2.6 years, height: 175.7 ± 6.5 cm, body mass 80.3 ± 10.1 kg) at the Infantry Training Centre, Catterick (ITC(C)) volunteered. Nutrient intakes and 24-h urinary nitrogen balance were assessed in weeks 2, 6 and 11 of BT. Nutrient intake was assessed using researcher-led weighed food records and food diaries, and Nutritics professional dietary software. Data were compared between weeks using a repeated-measures analysis of variance (ANOVA) with statistical significance set at p ≤ 0.05. There was a significant difference in protein intake (g) between weeks 2 and 11 of BT (115 ± 18 vs. 91 ± 20 g, p = 0.02, ES = 1.26). There was no significant difference in mean absolute daily energy (p = 0.44), fat (p = 0.79) or carbohydrate (CHO) intake (p = 0.06) between weeks. Nitrogen balance was maintained in weeks 2, 6 and 11, but declined throughout BT (2: 4.6 ± 4.1 g, 6: 1.6 ± 4.5 g, 11: −0.2 ± 5.5 g, p = 0.07). A protein intake of 1.5 g·kg−1·d−1 may be sufficient in the early stages of BT, but higher intakes may be individually needed later on in BT