2,446 research outputs found

    Mean values of Dirichlet polynomials and applications to linear equations with prime variables

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    We prove a new mean-value theorem for Dirichlet polynomials with coefficients given by the von Mangoldt function. We then use our theorem to derive new estimates for certain exponential sums over primes. The latter have applications to additive problems with prime variables. In particular, we are able to improve on a recent result of J.Y. Liu and K.M. Tsang on the size of the solutions of linear equations with prime variables

    An Interacting Parton Model for Quark and Anti-quark distributions in the Baryon

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    In this paper we study a 1+1 dimensional relativistic parton model for the structure of baryons. The quarks and anti-quarks interact through a linear potential. We obtain an analytic formula for the isospin averaged valence quark distribution in the chiral and large Nc limits. The leading 1/Nc and non-zero current quark mass corrections are estimated. Then we extend this model to include `sea' and anti-quarks. We find that the anti-quark content is small at a low value of Q^2. Using these distributions as initial conditions for Q^2 evolution, we compare with experimental measurements of the structure function xF_3(x,Q^2) and find reasonable agreement. The only parameters we can adjust are the fraction of baryon momentum carried by valence quarks and the initial scale Q_0^2.Comment: 14 page

    Detection of humidity-treated aged latent prints using cyanoacrylate fuming and a reflected ultraviolet imaging system (RUVIS)

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    For the past several decades, challenges in the detection and collection of latent prints exposed to harsh environmental conditions have inspired research in pretreatment methods prior to the application of chemical, physical, or optical-based enhancement techniques. Some of the difficulties associated with processing degraded latent prints are attributed to dehydration, alterations in chemical composition, and physical disturbance of ridge detail. This study seeks to investigate the effectiveness of humidity, cyanoacrylate fuming method (CFM), and a reflected ultraviolet imaging system (RUVIS) on the detection and collection of aged latent palmprints. Prints were exposed to air flow and ultraviolet (UV) light for a period of 0 to 28 days, and subsequently treated with either cool or warm humidity and CFM. RUVIS was then utilized to detect and capture friction ridge detail after each treatment step. Improvements in RUVIS detection between treatments were evaluated based on four response factors: minutiae count, percent print recovery, ridge thickness and contrast. By measuring these factors, each latent print photograph was able to be converted to quantifiable data to facilitate statistical analysis of potential differences or improvements between treatments. The results demonstrate that the application of 80% relative humidity successfully revived aged latent palmprints across all factors. The combined effect of humidity followed v by CFM treatment and RUVIS detection was greatest for minutiae count and ridge thickness, while percent print recovery and contrast demonstrated more modest improvements when compared to control prints. Additionally, cool temperature treatments outperformed warm temperature treatments across all factors except contrast. The data therefore suggest that to achieve print rejuvenation and overall improvements in RUVIS detection, combined cool humidity and CFM is more effective than humidity alone. The data also indicate a potential correlation between temperature treatments and latent print age. Warm humidity combined with CFM appeared to best enhance RUVIS images on fresher prints of a few days to one week old, while cool humidity and CFM appeared to maximally enhance RUVIS images on prints of several weeks old

    Relations between the SNO and the Super Kamiokande solar neutrino rates

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    By comparing the neutrino spectra measured by SNO and Super Kamiokande, we obtain inequalities between the ratios of observed rate to SSM rate for the two experiments. These inequalities apply to a possibly energy-dependent reduction of the SSM flux and to the case of neutrino oscillations. We use them to examine the relationship between the two experiments expected for the MSW and ``Just-So" oscillation scenarios.Comment: 8 pages + 3 figures, REVTeX, uuencoded file created on a VMS syste

    Solar neutrino interactions: Using charged currents at SNO to tell neutral currents at Super-Kamiokande

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    In the presence of flavor oscillations, muon and tau neutrinos can contribute to the Super-Kamiokande (SK) solar neutrino signal through the neutral current process \nu_{\mu,\tau} e^{-}\to \nu_{\mu,\tau} e^{-}. We show how to separate the \nu_e and \nu_{\mu,\tau} event rates in SK in a model independent way, by using the rate of the charged current process \nu_e d \to p p e^{-} from the Sudbury Neutrino Observatory (SNO) experiment, with an appropriate choice of the SK and SNO energy thresholds. Under the additional hypothesis of no oscillations into sterile states, we also show how to determine the absolute ^{8}B neutrino flux from the same data set, independently of the \nu_e survival probability.Comment: 14 pages (RevTeX), incl. 3 figures (epsf), submitted to Phys. ReV.

    Reclamation Ground Settlement Monitoring by Using GPS and Other Positioning Technologies at ShenZhen Airport.

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    Hong Kong is a small territory of about 1070 km2 . There is an ever-increasing demand for land to cope with her increasing development. Typical geology in Hong Kong under the seabed comprises a layer of soft marine deposit of variable thickness of up to 20 m, overlying alluvium, residual soil, decomposed rock and bedrock. However, the marine deposit is too soft to support any structures. Conventional reclamation practice in Hong Kong is to dredge the marine deposit, build the seawalls and fill the enclosed space by sand. This conventional approach has many shortcomings. A research project was undertaken by The University of Hong Kong to develop a vacuum preloading technique that is environmentally safe to improve the engineering properties of the thick layer of soft marine deposits so that they can be kept in place during land reclamation. As a result, the environmental problems relating to dredging can be completely eliminated. A vacuum preloading test near the Shenzhen Airport was carried out as part of a very large research program. Sub-surface field instrumentation comprised piezometers, inclinometers, extensometers and pressure cells to monitor the performance of the vacuum system and the physical changes of the marine deposit during vacuum preloading. Surface settlement was monitored using 3 units of high precision GPS equipment throughout the test for checking against the sub-surface monitored movement. It is necessary to use a fully automatic system like GPS for replacing conventional survey because the test was carried out over water, which was difficult to access and the test was carried out over a very long period of 4 months. This paper reports the use of GPS for reclamation ground settlement monitoring and demonstrates cm-level positioning results through experimental trials. The results also agree very well with the sub-surface settlement readings.published_or_final_versio

    Exact analysis of the combined data of SNO and Super-Kamiokande

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    Comparison of solar-neutrino signals in SNO and Super-Kamiokande (SK) detectors results in discovery of νeνμ,τ\nu_e \to \nu_{\mu,\tau} oscillations at level 3.13.3σ3.1 - 3.3 \sigma \cite{SNO}. This comparison involves the assumption of neutrino spectrum and a choice for the thresholds of detection in both experiments. In this Letter we obtain an exact formula for the comparison of the signals which is valid for arbitrary spectra and thresholds. We find that the no-oscillation hypothesis is excluded at 3.3σ\sigma. If the energy-dependent component of the survival probability for electron neutrinos is small as compared with the average value, i.e. in the case of small distortion of the observed spectrum, the oscillation hypothesis can also be tested to similar accuracy. The oscillation to sterile neutrino only, is excluded at 3.3σ3.3 \sigma level, and oscillation to active neutrinos is confirmed at the same level, though with some reservations.Comment: 11 pages, 1 Fig added, small revision, references adde

    The value of kinetic glomerular filtration rate estimation on medication dosing in acute kidney injury.

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    BackgroundIn acute kidney injury (AKI), medication dosing based on Cockcroft-Gault creatinine clearance (CrCl) or Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) estimated glomerular filtration rates (eGFR) are not valid when serum creatinine (SCr) is not in steady state. The aim of this study was to determine the impact of a kinetic estimating equation that incorporates fluctuations in SCrs on drug dosing in critically ill patients.MethodsWe used data from participants enrolled in the NIH Acute Respiratory Distress Syndrome Network Fluid and Catheters Treatment Trial to simulate drug dosing category changes with the application of the kinetic estimating equation developed by Chen. We evaluated whether kinetic estimation of renal function would change medication dosing categories (≥60, 30-59, 15-29, and <15mL/min) compared with the use of CrCl or CKD-EPI eGFR.ResultsThe use of kinetic CrCl and CKD-EPI eGFR resulted in a large enough change in estimated renal function to require medication dosing recategorization in 19.3% [95 CI 16.8%-21.9%] and 23.4% [95% CI 20.7%-26.1%] of participants, respectively. As expected, recategorization occurred more frequently in those with AKI. When we examined individual days for those with AKI, dosing discordance was observed in 8.5% of total days using the CG CrCl and 10.2% of total days using the CKD-EPI equation compared with the kinetic counterparts.ConclusionIn a critically ill population, use of kinetic estimates of renal function impacted medication dosing in a substantial proportion of AKI participants. Use of kinetic estimates in clinical practice should lower the incidence of medication toxicity as well as avoid subtherapeutic dosing during renal recovery

    AAV-mediated and pharmacological induction of Hsp70 expression stimulates survival of retinal ganglion cells following axonal injury.

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    We evaluated the effect of AAV2- and 17-AAG (17-N-allylamino-17-demethoxygeldanamycin)-mediated upregulation of Hsp70 expression on the survival of retinal ganglion cells (RGCs) injured by optic nerve crush (ONC). AAV2-Hsp70 expression in the retina was primarily observed in the ganglion cell layer. Approximately 75% of all transfected cells were RGCs. RGC survival in AAV2-Hsp70-injected animals was increased by an average of 110% 2 weeks after the axonal injury compared with the control. The increase in cell numbers was not even across the retinas with a maximum effect of approximately 306% observed in the inferior quadrant. 17-AAG-mediated induction of Hsp70 expression has been associated with cell protection in various models of neurodegenerative diseases. We show here that a single intravitreal injection of 17-AAG (0.2 ug ul(-1)) results in an increased survival of ONC-injured RGCs by approximately 49% compared with the vehicle-treated animals. Expression of Hsp70 in retinas of 17-AAG-treated animals was upregulated approximately by twofold compared with control animals. Our data support the idea that the upregulation of Hsp70 has a beneficial effect on the survival of injured RGCs, and the induction of this protein could be viewed as a potential neuroprotective strategy for optic neuropathies
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