153 research outputs found
Designing an optometric curriculum
This project will design an optometric curriculum for a theoretical college of optometry. The curriculum will be constructed from a students point of view while conforming to real world limitations
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AC magnetic field losses in BSCCO-2223 superconducting tapes
The AC magnetic losses at power frequencies (60 Hz) were investigated for mono- and multifilament Ag-sheathed (Bi, Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub y} (BSCCO-2223) tapes with similar transport critical current (I{sub c}) values at 77 K. The multifilament sample exhibited higher losses than the monofilament under the same conditions. Loss peaks are discussed in terms of intergranular, intragranular and eddy current losses. Because of BSCCO`s anisotropy, field orientation has a large effect on the magnitude of these peaks, even at relatively small angles. Losses for fields applied parallel to the c-axis of the textured BSCCO grains are larger by more than one order of magnitude than those applied perpendicular
Equations over free inverse monoids with idempotent variables
We introduce the notion of idempotent variables for studying equations in
inverse monoids.
It is proved that it is decidable in singly exponential time (DEXPTIME)
whether a system of equations in idempotent variables over a free inverse
monoid has a solution. The result is proved by a direct reduction to solve
language equations with one-sided concatenation and a known complexity result
by Baader and Narendran: Unification of concept terms in description logics,
2001. We also show that the problem becomes DEXPTIME hard , as soon as the
quotient group of the free inverse monoid has rank at least two.
Decidability for systems of typed equations over a free inverse monoid with
one irreducible variable and at least one unbalanced equation is proved with
the same complexity for the upper bound.
Our results improve known complexity bounds by Deis, Meakin, and Senizergues:
Equations in free inverse monoids, 2007.
Our results also apply to larger families of equations where no decidability
has been previously known.Comment: 28 pages. The conference version of this paper appeared in the
proceedings of 10th International Computer Science Symposium in Russia, CSR
2015, Listvyanka, Russia, July 13-17, 2015. Springer LNCS 9139, pp. 173-188
(2015
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Recent advances in processing of Ag-clad Bi-2223 superconductors
Enhancements in the transport current properties of long lengths of multifilament Ag-sheathed (Bi,Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub y} (Bi-2223) superconducting tapes were made as a function of increased packing density of precursor powder, improved mechanical deformation, and adjusted cooling rate. Improved processing parameters had a pronounced effect on the transport critical current (I{sub c}) of the superconducting tapes, at 77 K and zero applied magnetic field, an I{sub c} of 60 A was obtained in short length samples (4 cm), an I{sub c} of 54 A in a 164 m length, and 18 A in a 1,260 m length. These enhancements were based on the increase in packing density accompanied with improved mechanical deformation and cooling schedule. Maximum critical current values were two to three times higher in slow-cooled tapes than in fast-cooled tapes
Humans rather than Eurasian lynx (Lynx lynx) shape ungulate browsing patterns in a temperate forest
The recolonization of human-dominated landscapes by large carnivores has been followed with considerable scientific interest; however, little is known about their interactive effect on ungulate foraging behavior. This study compared the risks imposed by humans and lynx on ungulate foraging behavior by examining the effects of browsing intensity (at two spatial scales), diet quality, and tree species selection. We hypothesized that: (1) in areas with high risk imposed by humans and lynx browsing intensity would be reduced; (2) risk effects would interact with habitat visibility at a fine scale, resulting in contrasting browsing patterns in response to humans versus lynx risk; (3) ungulates compensate for the higher costs incurred in high-risk areas by switching to a higher diet quality, and (4) browse a higher proportion of more-preferred tree species. These hypotheses were tested by measuring browsing intensity along 48 transects located at different distances from human settlements within the hunted and nonhunted areas of the Bavarian Forest. Dung samples were collected and analyzed as a proxy of diet quality (C:N ratio, fiber). The spatial patterns of browsing intensity, diet quality, and tree species selection were then linked to lynx risk, hunting intensity, recreation intensity, and distance to human settlements. Our results showed that (1) browsing intensity strongly decreased with increasing recreational activities, whereas it increased with lynx risk; (2) only in close proximity to human settlements tree browsing was higher in dense habitats and (3) a higher diet quality was obtained. (4) We found a stronger avoidance of the less preferred tree species in high-hunting intensity areas. In conclusion, our results indicate that the risk effects of human activities outweigh those of a natural large carnivore. Thus, highlighting the importance of taking those activities into account in predicting the impacts of large carnivores on ungulates and their plant-food choices.publishedVersio
Resting and exercise haemodynamic characteristics of patients with advanced heart failure and preserved ejection fraction
Aims:
This study aimed to describe haemodynamic features of patients with advanced heart failure with preserved ejection fraction (HFpEF) as defined by the Heart Failure Association (HFA) of the European Society of Cardiology (ESC).
Methods and results:
We used pooled data from two dedicated HFpEF studies with invasive exercise haemodynamic protocols, the REDUCE LAP-HF (Reduce Elevated Left Atrial Pressure in Patients with Heart Failure) trial and the REDUCE LAP-HF I trial, and categorized patients according to advanced heart failure (AdHF) criteria. The well-characterized HFpEF patients were considered advanced if they had persistent New York Heart Association classification of III–IV and heart failure (HF) hospitalization < 12 months and a 6 min walk test distance < 300 m. Twenty-four (22%) out of 108 patients met the AdHF criteria. On evaluation, clinical characteristics and resting haemodynamics were not different in the two groups. Patients with AdHF had lower work capacity compared with non-advanced patients (35 ± 16 vs. 45 ± 18 W, P = 0.021). Workload-corrected pulmonary capillary wedge pressure normalized to body weight (PCWL) was higher in AdHF patients compared with non-advanced (112 ± 55 vs. 86 ± 49 mmHg/W/kg, P = 0.04). Further, AdHF patients had a smaller increase in cardiac index during exercise (1.1 ± 0.7 vs. 1.6 ± 0.9 L/min/m2, P = 0.028).
Conclusions:
A significantly higher PCWL and lower cardiac index reserve during exercise were observed in AdHF patients compared with non-advanced. These differences were not apparent at rest. Therapies targeting the haemodynamic compromise associated with advanced HFpEF are needed
Marine Ecoregion and Deepwater Horizon Oil Spill Affect Recruitment and Population Structure of a Salt Marsh Snail
Marine species with planktonic larvae often have high spatial and temporal variation in recruitment that leads to subsequent variation in the ecology of benthic adults. Using a combination of published and unpublished data, we compared the population structure of the salt marsh snail, Littoraria irrorata, between the South Atlantic Bight and the Gulf Coast of the United States to infer geographic differences in recruitment and to test the hypothesis that the Deepwater Horizon oil spill led to widespread recruitment failure of L. irrorata in Louisiana in 2010. Size-frequency distributions in both ecoregions were bimodal, with troughs in the distributions consistent with a transition from sub-adults to adults at ~13 mm in shell length as reported in the literature; however, adult snails reached larger sizes in the Gulf Coast. The ratio of sub-adults to adults was 1.5–2 times greater in the South Atlantic Bight than the Gulf Coast, consistent with higher recruitment rates in the South Atlantic Bight. Higher recruitment rates in the South Atlantic Bight could contribute to higher snail densities and reduced adult growth in this region. The ratio of sub-adults to adults in Louisiana was lower in 2011 than in previous years, and began to recover in 2012–2014, consistent with widespread recruitment failure in 2010, when large expanses of spilled oil were present in coastal waters. Our results reveal an important difference in the ecology of a key salt marsh invertebrate between the two ecoregions, and also suggest that the Deepwater Horizon oil spill may have caused widespread recruitment failure in this species and perhaps others with similar planktonic larval stages
Complement C1 Esterase Inhibitor Levels Linked to Infections and Contaminated Heparin-Associated Adverse Events
Activation of kinin-kallikrein and complement pathways by oversulfated-chondroitin-sulfate (OSCS) has been linked with recent heparin-associated adverse clinical events. Given the fact that the majority of patients who received contaminated heparin did not experience an adverse event, it is of particular importance to determine the circumstances that increase the risk of a clinical reaction. In this study, we demonstrated by both the addition and affinity depletion of C1inh from normal human plasma, that the level of C1inh in the plasma has a great impact on the OSCS-induced kallikrein activity and its kinetics. OSCS-induced kallikrein activity was dramatically increased after C1inh was depleted, while the addition of C1inh completely attenuated kallikrein activity. In addition, actual clinical infection can lead to increased C1inh levels. Plasma from patients with sepsis had higher average levels of functional C1inh and decreased OSCS-induced kallikrein activity. Lastly, descriptive data on adverse event reports suggest cases likely to be associated with contaminated heparin are inversely correlated with infection. Our data suggest that low C1inh levels can be a risk factor and high levels can be protective. The identification of risk factors for contact system-mediated adverse events may allow for patient screening and clinical development of prophylaxis and treatments
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50 MW X-BAND RF SYSTEM FOR A PHOTOINJECTOR TEST STATION AT LLNL
In support of X-band photoinjector development efforts at LLNL, a 50 MW test station is being constructed to investigate structure and photocathode optimization for future upgrades. A SLAC XL-4 klystron capable of generating 50 MW, 1.5 microsecond pulses will be the high power RF source for the system. Timing of the laser pulse on the photocathode with the applied RF field places very stringent requirements on phase jitter and drift. To achieve these requirements, the klystron will be powered by a state of the art, solid-state, high voltage modulator. The 50 MW will be divided between the photoinjector and a traveling wave accelerator section. A high power phase shifter is located between the photoinjector and accelerator section to adjust the phasing of the electron bunches with respect to the accelerating field. A variable attenuator is included on the input of the photoinjector. The distribution system including the various x-band components is being designed and constructed. In this paper, we will present the design, layout, and status of the RF system
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Overview of MEGa-ray-based Nuclear Materials Management Activities at the Lawrence Livermore National Laboratory
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