Ultrafast Raman laser mode-locked by nanotubes

We demonstrate passive mode-locking of a Raman fiber laser using a nanotube-based saturable absorber coupled to a net normal dispersion cavity. This generates highly chirped 500 ps pulses. These are then compressed down to 2 ps , with 1.4 kW peak power, making it a simple wavelength-versatile source for various applications

Regional pressure and temperature differences across the injured human brain : comparisons between intraparenchymal and ventricular measurements

Introduction: Intraparenchymal, multimodality sensors are commonly used in the management of patients with severe traumatic brain injury (TBI). The ‘gold standard’, based on accuracy, reliability and cost for intracranial pressure (ICP) monitoring is within the cerebral ventricle (external strain gauge). There are no standards yet for intracerebral temperature monitoring and little is known of temperature differences between brain tissue and ventricle. The aim of the study therefore was to determine pressure and temperature differences at intraparenchymal and ventricular sites during five days of continuous neurominitoring. Methods: Patients with severe TBI requiring emergency surgery. Inclusion criteria: patients who required ICP monitoring were eligible for recruitment. Two intracerebral probe types were used: a) intraventricular, dual parameter sensor (measuring pressure, temperature) with inbuilt catheter for CSF drainage: b) multiparameter intraparenchymal sensor measuring pressure, temperature and oxygen partial pressure. All sensors were inserted during surgery and under aseptic conditions. Results: Seventeen patients, 12 undergoing neurosurgery (decompressive craniectomy n=8, craniotomy n=4) aged 21–78 years were studied. Agreement of measures for 9540 brain tissue-ventricular temperature ‘pairs’ and 10,291 brain tissue-ventricular pressure ‘pairs’ were determined using mixed model to compare mean temperature and pressure for longitudinal data. There was no significant overall difference for mean temperature (p=0.92) or mean pressure readings (p=0.379) between tissue and ventricular sites. With 95.8% of paired temperature readings within 2SD (−0.4 to 0.4°C) differences in temperature between brain tissue and ventricle were clinically insignificant. For pressure, 93.5% of readings pairs fell within the 2SD range (−9.4756 to 7.8112 mmHg) (Fig. 2). However, for individual patients, agreement for mean tissue-ventricular pressure differences was poor on occasions. Conclusions: There is good overall agreement between paired temperature measurements obtained from deep white matter and brain ventricle in patients with and without early neurosurgery. For paired ICP measurements, 93.5% of readings were within 2SD of mean difference. Whilst the majority of paired readings were comparable (within 10mmHg) clinically relevant tissue-ventricular dissociations were noted. Further work is required to unravel the events responsible for short intervals of pressure dissociation before tissue pressure readings can be definitively accepted as a reliable surrogate for ventricular pressure.</p

Hamiltonian submanifolds of regular polytopes

We investigate polyhedral $2k$-manifolds as subcomplexes of the boundary complex of a regular polytope. We call such a subcomplex {\it $k$-Hamiltonian} if it contains the full $k$-skeleton of the polytope. Since the case of the cube is well known and since the case of a simplex was also previously studied (these are so-called {\it super-neighborly triangulations}) we focus on the case of the cross polytope and the sporadic regular 4-polytopes. By our results the existence of 1-Hamiltonian surfaces is now decided for all regular polytopes. Furthermore we investigate 2-Hamiltonian 4-manifolds in the $d$-dimensional cross polytope. These are the "regular cases" satisfying equality in Sparla's inequality. In particular, we present a new example with 16 vertices which is highly symmetric with an automorphism group of order 128. Topologically it is homeomorphic to a connected sum of 7 copies of $S^2 \times S^2$. By this example all regular cases of $n$ vertices with $n < 20$ or, equivalently, all cases of regular $d$-polytopes with $d\leq 9$ are now decided.Comment: 26 pages, 4 figure

The Crystal Ball Data Acquisition System

The data acquisition system for the Crystal Ball project at SLAC is described. A PDP-11/t55 using RSX-11M connected to the SLAC Triplex is the basis of the system. A "physics pipeline" allows physicists to write their own equipment-monitoring or physics tasks which require event sampling. As well, an interactive analysis package (MULTI) is in the pipeline. Histogram collection and display on the PDP are implemented using the Triplex histogramming package. Various interactive event displays are also implemented

Genetic Sequencing Methodologies to Assess Human Contributions of Fecal Coliforms to a Freshwater Receiving Stream

2012 S.C. Water Resources Conference - Exploring Opportunities for Collaborative Water Research, Policy and Managemen

Prey of reintroduced fishers and their habitat relationships in the Cascades T Range, Washington

Conservation and recovery of forest carnivores requires an understanding of their habitat requirements, as well as requirements of their prey. In much of the western United States, trapping and habitat loss led to extirpations of fishers (Pekania pennanti) by the mid-20th century, and reintroductions are ongoing to restore fishers to portions of their former range. Fisher recovery in Washington State has been limited by isolation from other populations, but other potentially important factors, such as diet of fishers in this region and prey availability, have not been thoroughly investigated. We collected hair samples from potential prey and fishers for stable isotope analysis to identify important prey items for fishers within a reintroduction area in southern Washington. We then estimated the abundance of prey species at 21 sites across a gradient of forest structural classes within the fisher reintroduction area, and assessed the effects of forest age and vegetation on the prey community using permutational multivariate analysis of variance and non-metric multidimensional scaling. Stable isotopes revealed that larger prey items, including snowshoe hares (Lepus americanus) and/or mountain beavers (Aplodontia rufa), were the most important prey item(s) for fishers in the southern Cascades. We found distinct but equally diverse prey communities in old-growth (unmanaged) and young (heavily managed) forest stands, with snowshoe hares and mountain beavers most common in young forests, while chipmunks (Neotamius spp.) and small mammals were more common in older forests. Our results suggest a discrepancy between the habitats where important fisher prey are most abundant and habitat requirements of fishers. Snowshoe hares and mountain beavers were most abundant in young forests, whereas fishers are associated with landscapes dominated by older forest stands or those that provide large woody structures, which fishers use for denning and resting. Our results add to growing evidence that forest landscape mosaics provide valuable habitat for fishers in the Pacific Northwest, suggesting that both mature and younger forest stands are important for fishers and fisher recovery

Chiropractic at the crossroads or are we just going around in circles?

Chiropractic in Australia has seen many changes over the past 30 years. Some of these changes have advanced the professional status of chiropractic, improved undergraduate training and paved the way for a research culture. Unfortunately, other changes or lack of changes, have hindered the growth, public utilisation and professional standing of chiropractic in Australia. This article explores what influences have impacted on the credibility, advancement and public utilisation of chiropractic in Australia

Knee loading stimulates cortical bone formation in murine femurs

BACKGROUND: Bone alters its architecture and mass in response to the mechanical environment, and thus varying loading modalities have been examined for studying load-driven bone formation. The current study aimed to evaluate the anabolic effects of knee loading on diaphyseal cortical bone in the femur. METHODS: Using a custom-made piezoelectric loader, 0.5-N loads were laterally applied to the left knee of C57/BL/6 mice at 5, 10, 15, and 20 Hz for 3 minutes per day for 3 consecutive days. Animals were sacrificed for examination 13 days after the last loading. The contralateral femur was used as a non-loading control, and the statistical significance of loading effects was evaluated with p < 0.05. RESULTS: Although diaphyseal strains were measured as small as 12 μstrains, bone histomorphometry clearly demonstrated frequency-dependent enhancement of bone formation. Compared to a non-loading control, bone formation on the periosteal surface was significantly enhanced. The loading at 15 Hz was most effective in elevating the mineralizing surface (1.7 x; p < 0.05), mineral apposition rate (1.4 x; p < 0.001), and bone formation rate (2.4 x; p < 0.01). The loading at 10 Hz elevated the mineralizing surface (1.4 x; p < 0.05), mineral apposition rate (1.3 x; p < 0.01), and bone formation rate (1.8 x; p < 0.05). The cross-sectional cortical area and the cortical thickness in the femoral diaphysis were significantly increased by loading at 10 Hz (both 9%) and 15 Hz (12% and 13%, respectively). CONCLUSION: The results support the anabolic effects of knee loading on diaphyseal cortical bone in the femur with small in situ strain, and they extend our knowledge on the interplay between bone and joints. Strengthening the femur contributes to preventing femoral fractures, and the discovery about the described knee loading might provide a novel strategy to strengthen osteoporotic bones. Further analyses are required to understand the biophysical and molecular mechanism behind knee loading

Using indirect methods to constrain symbiotic nitrogen fixation rates : a case study from an Amazonian rain forest

© The Authors 2009. This article is distributed under the terms of the Creative Commons Attribution Noncommercial License. The definitive version was published in Biogeochemistry 99 (2010): 1-13, doi:10.1007/s10533-009-9392-y.Human activities have profoundly altered the global nitrogen (N) cycle. Increases in anthropogenic N have had multiple effects on the atmosphere, on terrestrial, freshwater and marine ecosystems, and even on human health. Unfortunately, methodological limitations challenge our ability to directly measure natural N inputs via biological N fixation (BNF)—the largest natural source of new N to ecosystems. This confounds efforts to quantify the extent of anthropogenic perturbation to the N cycle. To address this gap, we used a pair of indirect methods—analytical modeling and N balance—to generate independent estimates of BNF in a presumed hotspot of N fixation, a tropical rain forest site in central Rondônia in the Brazilian Amazon Basin. Our objectives were to attempt to constrain symbiotic N fixation rates in this site using indirect methods, and to assess strengths and weaknesses of this approach by looking for areas of convergence and disagreement between the estimates. This approach yielded two remarkably similar estimates of N fixation. However, when compared to a previously published bottom-up estimate, our analysis indicated much lower N inputs via symbiotic BNF in the Rondônia site than has been suggested for the tropics as a whole. This discrepancy may reflect errors associated with extrapolating bottom-up fluxes from plot-scale measures, those resulting from the indirect analyses, and/or the relatively low abundance of legumes at the Rondônia site. While indirect methods have some limitations, we suggest that until the technological challenges of directly measuring N fixation are overcome, integrated approaches that employ a combination of model-generated and empirically-derived data offer a promising way of constraining N inputs via BNF in natural ecosystems.We acknowledge and are grateful for financial support from the Andrew W. Mellon Foundation (C.C. and B.H.), the National Science Foundation (NSF DEB-0515744 to C.C. and A.T. and DEB-0315656 to C.N.), and the NASA LBA Program (NCC5-285 to C.N.)