Inverse four-wave mixing and self-parametric amplification in optical fibre

An important group of nonlinear processes in optical fibre involve the mixing of four waves due to the intensity dependence of the refractive index. It is customary to distinguish between nonlinear effects that require external/pumping waves (cross-phase modulation and parametric processes such as four-wave mixing) and those arising from self-action of the propagating optical field (self-phase modulation and modulation instability). Here, we present a new nonlinear self-action effect—self-parametric amplification—which manifests itself as optical spectrum narrowing in normal dispersion fibre, leading to very stable propagation with a distinctive spectral distribution. The narrowing results from inverse four-wave mixing, resembling an effective parametric amplification of the central part of the spectrum by energy transfer from the spectral tails. Self-parametric amplification and the observed stable nonlinear spectral propagation with a random temporal waveform can find applications in optical communications and high-power fibre lasers with nonlinear intracavity dynamics

Induction and Amplification of Non-Newtonian Gravitational Fields

One obtains a Maxwell-like structure of gravitation by applying the weak-field approximation to the well accepted theory of general relativity or by extending Newton's laws to time-dependent systems. This splits gravity in two parts, namely a gravitoelectric and gravitomagnetic (or cogravitational) one. Due to the obtained similar structure between gravitation and electromagnetism, one can express one field by the other one using a coupling constant depending on the mass to charge ratio of the field source. Calculations of induced gravitational fields using state-of-the-art fusion plasmas reach only accelerator threshold values for laboratory testing. Possible amplification mechanisms are mentioned in the literature and need to be explored. The possibility of using the principle of equivalence in the weak field approximation to induce non-Newtonian gravitational fields and the influence of electric charge on the free fall of bodies are also investigated, leading to some additional experimental recommendations

Blood immunometabolic indices and polymorphonuclear neutrophil function in peripartum dairy cows are altered by level of dietary energy prepartum

Cows experience some degree of negative energy balance and immunosuppression around parturition, making them vulnerable to metabolic and infectious diseases. The effect of prepartum feeding of diets to meet (control, 1.34 Mcal/kg of dry matter) or exceed (overfed, 1.62 Mcal/kg of dry matter) dietary energy requirements was evaluated during the entire dry period (∼45 d) on blood polymorphonuclear neutrophil function, blood metabolic and inflammatory indices, and milk production in Holstein cows. By design, dry matter intake in the overfed group (n=9) exceeded energy requirements during the prepartum period (-4 to -1 wk relative to parturition), resulting in greater energy balance when compared with the control group (n=10). Overfed cows were in more negative energy balance during wk 1 after calving than controls. No differences were observed in dry matter intake, milk yield, and milk composition between diets. Although nonesterified fatty acid concentration pre- (0.138 mEq/L) and postpartum (0.421 mEq/L) was not different between diets, blood insulin concentration was greater in overfed cows prepartum (16.7 μIU/mL) compared with controls pre- and postpartum (∼3.25 μIU/mL). Among metabolic indicators, concentrations of urea (4.63 vs. 6.38 mmol/L), creatinine (100 vs. 118 μmol/L), and triacylglycerol (4.0 vs. 8.57 mg/dL) in overfed cows were lower prepartum than controls. Glucose was greater pre- (4.24 vs. 4.00 mmol/L) and postpartum (3.49 vs. 3.30 mmol/L) compared with control cows. Among liver function indicators, the concentration of bilirubin increased by 2 to 6 fold postpartum in control and overfed cows. Phagocytosis capacity of polymorphonuclear neutrophils was lower prepartum in overfed cows (32.7% vs. 46.5%); phagocytosis in the control group remained constant postpartum (50%) but it increased at d 7 in the overfed group to levels similar to controls (48.4%). Regardless of prepartum diet, parturition was characterized by an increase in nonesterified fatty acid and liver triacylglycerol, as well as blood indices of inflammation (ceruloplasmin and haptoglobin), oxidative stress (reactive oxygen metabolites), and liver injury (glutamic oxaloacetic transaminase). Concentrations of the antioxidant and anti-inflammatory compounds vitamin A, vitamin E, and β-carotene decreased after calving. For vitamin A, the decrease was observed in overfed cows (47.3 vs. 27.5 μg/100 mL). Overall, overfeeding energy and higher energy status prepartum led to the surge of insulin and had a transient effect on metabolism postpartum

Effects of a nanoscopic filler on the structure and dynamics of a simulated polymer melt and the relationship to ultra-thin films

We perform molecular dynamics simulations of an idealized polymer melt surrounding a nanoscopic filler particle to probe the effects of a filler on the local melt structure and dynamics. We show that the glass transition temperature $T_g$ of the melt can be shifted to either higher or lower temperatures by appropriately tuning the interactions between polymer and filler. A gradual change of the polymer dynamics approaching the filler surface causes the change in the glass transition. We also find that while the bulk structure of the polymers changes little, the polymers close to the surface tend to be elongated and flattened, independent of the type of interaction we study. Consequently, the dynamics appear strongly influenced by the interactions, while the melt structure is only altered by the geometric constraints imposed by the presence of the filler. Our findings show a strong similarity to those obtained for ultra-thin polymer films (thickness $\lesssim 100$ nm) suggesting that both ultra-thin films and filled-polymer systems might be understood in the same context

Repair of large sinus membrane perforations using stabilized collagen barrier membranes : surgical techniques with histologic and radiographic evidence of success

The most frequent intraoperative complication with sinus elevation is perforation of the schneiderian membrane. In most instances, the repair of this perforation is necessary to contain particulate grafting material and complete the procedure. New techniques are presented here for the management of large perforations of the schneiderian membrane. A bioabsorbable collagen membrane is stabilized outside the antrostomy and then folded inward to create either a new superior wall that can obliterate a large perforation or a “pouch” that can completely contain the particulate material. This can make it possible to complete a procedure that otherwise may have had to be aborted by preventing dispersion of the particulate graft within the sinus cavity. Clinical cases are shown, along with follow-up at 6 to 9 months, demonstrating histologic and/or radiographic evidence of success, continued sinus health, and superior vital bone formation. The authors have used this technique on 20 consecutive patients without experiencing any procedural failures

Failing boys and moral panics: perspectives on the underachievement debate

The paper re-examines the underachievement debate from the perspective of the ‘discourse of derision’ that surrounds much writing in this area. It considers the contradictions and inconsistencies which underpin much of the discourse – from a reinterpretation of examination scores, to the conflation of the concepts of ‘under’ and ‘low’ achievement and finally to the lack of consensus on a means of defining and measuring the term underachievement. In doing so, this paper suggests a more innovative approach for understanding, re-evaluating and perhaps rejecting the notion of underachievement

Professionalism, Golf Coaching and a Master of Science Degree: A commentary

As a point of reference I congratulate Simon Jenkins on tackling the issue of professionalism in coaching. As he points out coaching is not a profession, but this does not mean that coaching would not benefit from going through a professionalization process. As things stand I find that the stimulus article unpacks some critically important issues of professionalism, broadly within the context of golf coaching. However, I am not sure enough is made of understanding what professional (golf) coaching actually is nor how the development of a professional golf coach can be facilitated by a Master of Science Degree (M.Sc.). I will focus my commentary on these two issues

Outside in-group and out-group identities? Constructing male solidarity and female exclusion in UK builders’ talk

This article examines the spoken interactions of a group of British construction workers to discover whether it is possible to identify a distinctive ‘builders’ discourse’. Given that builders work for a mostly all-male profession (Curjao, 2006), we ask whether the ways in which male builders converse with each other while ‘on the job’ can be held in any way responsible for the under-representation of women within this major occupational sector in the UK. This article reports on a case study of the conversations of three white, working-class, male builders, which took place while travelling in a truck between different building sites. This forms part of a larger ethnographic study of builders’ discourse in different work locations. The analysis shows that male builders are highly collaborative in constructing narratives of in-group and out-group identities (Duszak, 2002; Tajfel, 1978). Various other male groups are demonized in these conversations: Polish immigrant builders, rude clients and rival builders. However, there is almost no reference to women. The article concludes that women are viewed as so unthreatening to male ascendancy in the building industry that they do not even feature within the ‘out-group’

Partitioning the effects of habitat loss hunting and climate change on the endangered Chacoan peccary

Aim: Land-use change and overexploitation are major threats to biodiversity, and cli mate change will exert additional pressure in the 21st century. Although there are strong interactions between these threats, our understanding of the synergistic and compensatory effects on threatened species' range geography remains limited. Our aim was to disentangle the impact of habitat loss, hunting and climate change on spe cies, using the example of the endangered Chacoan peccary (Catagonus wagneri). Location: Gran Chaco ecoregion in South America. Methods: Using a large occurrence database, we integrated a time-calibrated species distribution model with a hunting pressure model to reconstruct changes in the distri bution of suitable peccary habitat between 1985 and 2015. We then used partitioning analysis to attribute the relative contribution of habitat change to land-use conver sion, climate change and varying hunting pressure. Results: Our results reveal widespread habitat deterioration, with only 11% of the habitat found in 2015 considered suitable and safe. Hunting pressure was the strong est single threat, yet most habitat deterioration (58%) was due to the combined, rather than individual, effects of the three drivers we assessed. Climate change would have led to a compensatory effect, increasing suitable habitat area, yet this effect was ne gated by the strongly negative and interacting threats of land-use change and hunting. Main Conclusions: Our study reveals the central role of overexploitation, which is often neglected in biogeographic assessments, and suggests that addressing overex ploitation has huge potential for increasing species' adaptive capacity in the face of climate and land-use change. More generally, we highlight the importance of jointly assessing extinction drivers to understand how species might fare in the 21st century. Here, we provide a simple and transferable framework to determine the separate and joint effects of three main drivers of biodiversity loss.Fil: Torres, Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Diversidad y Ecología Animal ; Argentina.Fil: Kuemmerle, Tobias. Humboldt-University Berlin. Integrative Research Institute for Transformations in Human Environment Systems. Geography Department; AlemaniaFil: Baumann, Matthias. Humboldt-University. Geography Department; Alemania.Fil: Romero Muñoz, Alfredo. Humboldt University. Geography Departament; Alemania. University of British Columbia. Institute for Resources, Environment and Sustainability (IRES); Canada. Helmholtz Centre for Environmental Research. Department Computational Landscape Ecology; Alemania. Transformations of Human-Environment Systems (IRI THESys). Integrative Research Institute; AlemaniaFil: Altrichter, Mariana. IUCN SSC Peccary Specialist Group; Suiza. Prescott College. Environmental Studies; Estados UnidosFil: Boaglio, Gabriel Ivan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; ArgentinaFil: Cabral, Hugo. Universidade Estadual Paulista. Programa de Pós-Graduação em Biologia Animal; Brasil. Instituto de Investigación Biológica del Paraguay; ParaguayFil: Camino, Micaela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Ecología del Litoral. Laboratorio de Biología de la Conservación; ArgentinaFil: Campos Kraver, Juan M. University of Florida. College of Veterinary Medicine & Department of Wildlife Ecology and Conservation. Department of Large Animal Clinical Sciences; Estados UnidosFil: Giordano, Anthony. Society for the Preservation of Endangered Carnivores and their International Ecological Study (S.P.E.C.I.E.S); Estados Unidos. University of Los Angeles. Institute of the Environment and Sustainability. Center for Tropical Research; Estados UnidosFil: Cartes, José L. Guyra Paraguay, Parque del Río; ParaguayFil: Cuéllar, Rosa L. Fundación para la Conservación del Bosque Chiquitano; BoliviaFil: Decarre, Julieta. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Recursos Biológicos; ArgentinaFil: Gallegos, Marcelo. Provincia de Salta. Secretaría de Ambiente; ArgentinaFil: Lizárraga, Leónidas. Administración De Parques Nacionales. Dirección Regional Noroeste. Salta; Argentina.Fil: Maffei, Leonardo. Biósfera Consultores Ambientales, Lima, Perú.Fil: Neris, Nora N. Secretaria del Ambiente; ParaguayFil: Quiroga, Verónica. Universidad Nacional de Córdoba. Inst. de Diversidad y Ecología Animal (IDEA – CONICET), Centro de Zoología Aplicada; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Saldivar, Silvia. ITAIPU Binacional. Dirección de Coordinación. División de Áreas Protegidas; ParaguayFil: Tamburini, Daniela Maria. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Centro de Ecología y Recursos Naturales Renovables; Argentin

Detector Description and Performance for the First Coincidence Observations between LIGO and GEO

For 17 days in August and September 2002, the LIGO and GEO interferometer gravitational wave detectors were operated in coincidence to produce their first data for scientific analysis. Although the detectors were still far from their design sensitivity levels, the data can be used to place better upper limits on the flux of gravitational waves incident on the earth than previous direct measurements. This paper describes the instruments and the data in some detail, as a companion to analysis papers based on the first data.Comment: 41 pages, 9 figures 17 Sept 03: author list amended, minor editorial change