911 research outputs found
On the mean number of encryptions for tree-based broadcast encryption schemes
AbstractThe challenge of stateless-receiver broadcast encryption lies in minimizing storage and the number of encryptions while maintaining system security. Tree-based key distribution schemes offer the best known trade-off between the two parameters. Examples include the complete subtree scheme [D. Wallner, et al., Internet draft, http://www.ietf.org/ID.html [10]; C.K. Wong, et al., in: Proc. SIGCOMM, 1998, pp. 68â79 [11]], the subset difference scheme [D. Naor, et al., in: CRYPTO 2001, Lecture Notes in Comput. Sci., vol. 2139, 2001, pp. 41â62 [7]], and the layered subset difference scheme [D. Halevy, A. Shamir, in: CRYPTO 2002, Lecture Notes in Comput. Sci., vol. 2442, 2002, pp. 47â60 [5]]. We introduce generating functions for this family of schemes, which lead to analysis of the mean number of encryptions over all privileged sets of users. We also derive the mean number of encryptions when the number of privileged users is fixed. We expect that the techniques introduced as well as the results in this work will find applications in related areas
Metabolic changes during he transition period
We used four ruminally fistulated, multiparous, pregnant Holstein cows to measure changes in concentrations of plasma metabolite as the dairy cow transitions from one lactation to the next. Diets consisted of typical far-off and close-up diets, a late lactation diet containing wet corn gluten feed (20% DM), and an alfalfa hay-corn silage based early lactation diet. Calculated NEL (Mcal/lb), measured crude protein (%), and diet digestibilities (%; based on steers fed at 2% of BW) were 0.78, 18.7, 74.1; 0.70, 11.5, 66.2; 0.74, 15.6, 71.0; 0.73, 18.4, 70.7 for late lactation, far-off dry, close-up dry, and early lactation diets, respectively. Blood samples were obtained on day 79 prior to calving and weekly thereafter until calving and on days 1, 3, 5, 7, 15, 20, 25, 30, 60, and 90 after calving. Cows gained body weight and condition during the dry period, peaked just prior to calving, and lost weight and condition steadily through the first 11 weeks of lactation. Calculated energy balance was negative during the first 3 weeks of lactation. Plasma concentrations of non-esterified fatty acids (NEFA), glucose, and insulin to glucagon ratio remained fairly stable during the dry period. Plasma glucose increased just before calving, decreased markedly during early lactation, then increased and stabilized by day 30 of lactation. Plasma NEFA concentrations increased at calving and were elevated during early lactation, then returned to prepartum concentrations by day 30 of lactation. The insulin to glucagon ratio decreased just prior to calving, continued to decrease until day 7 of lactation, and then remained stable until the end of the trial. Changes in diet and intake affected plasma urea nitrogen, which decreased as dietary protein decreased during the far-off period, decreased with intake during the close-up period, and increased after calving consistent with the higher dietary protein and increase in dry matter intake. Most of the observed metabolic adaptations reflected the energy status of the cow with large shifts occurring around parturition. Certainly, some of the hormones associated with calving can initiate metabolic events favorable to lactation, but the changes in energy balance and nutrient supply support the continued diversion of nutrients to the mammary gland. These data support the concept that dairy cows experience a period of increased tissue mobilization from approximately 2 days prior to calving until 30 days after calving. In conclusion, a number of metabolic adaptations occur in transition dairy cows that provide clues to improve feeding and management guidelines.; Dairy Day, 2002, Kansas State University, Manhattan, KS, 2002
Labyrinthine fĂstulae in chronic otitis media with cholesteatoma
The chronic otitis media with cholesteatoma (COMC) may evoluate to intracranial and extra cranial complications, including the labyrithine fĂstulae. In this study, we present the evolution of our patients with labyrinthine fĂstulae. STUDY DESIGN: Clinical prospective. MATERIAL AND METHOD: Ten out 82 patients with COMC had labyrinthine fĂstulae and underwent surgery from January/2001 to April/2002. They were assessed by clinical exam, computed tomography scans, and pre and postoperative audiogram. RESULTS: Hearing loss, otorrhea, tinnitus and dizziness were present in 100%, 90%,80%, and 40% of the cases. In one patient the fĂstulae was seen only in the coronal CT-scan, in another patient the fĂstulae was not seen neither in coronal nor axial images. Among the patients who had tinnitus, 66% referred improvement of this complaint after surgery. DISCUSSION: in the cases without invasion of the perilymphatic space, we noticed a tendency of improvement of the postoperative audiogram pattern and clinical outcome. In the extensive fĂstulae, on the other hand, there were no clinical changes. CONCLUSION: The CT-scan remains the best exam to assess the COMC with 90% of sensitivity for labyrinthine fĂstulae. In the stage II we had a good postoperative outcome.A otite mĂ©dia crĂŽnica colesteatomatosa (OMCC) pode cursar com complicaçÔes intra e/ou extracranianas, entre elas a fĂstula labirĂntica. Neste trabalho, mostramos a incidĂȘncia e a evolução dos casos de fĂstula labirĂntica decorrentes da OMCC em nosso serviço. FORMA DE ESTUDO: ClĂnico prospectivo. MATERIAL E MĂTODO: Dez pacientes com fĂstula labirĂntica, do total de 82 pacientes com OMCC, foram submetidos Ă cirurgia no perĂodo de janeiro de 2001 a abril de 2002 e avaliados atravĂ©s de exame otorrinolaringolĂłgico completo, tomografia computadorizada e audiometria prĂ© e pĂłs-operatĂłria. RESULTADOS: Perda auditiva, otorrĂ©ia, zumbido e vertigem estavam presentes em 100%, 90%, 80% e 40% dos casos respectivamente na avaliação clĂnica prĂ©-operatĂłria. Em um paciente a fĂstula aparecia apenas nos cortes tomogrĂĄficos coronais e tivemos um caso de falso-negativo. Dos pacientes com zumbido, 66% apresentaram melhora deste quadro no pĂłs-operatĂłrio. DISCUSSĂO: Nos casos de fĂstula sem invasĂŁo do espaço perilinfĂĄtico (atĂ© grau II), notamos uma tendĂȘncia de melhora dos quadros clĂnico e audiomĂ©trico apĂłs a cirurgia. Nas fĂstulas extensas, por outro lado, o resultado audiomĂ©trico se manteve inalterado. CONCLUSĂO: A tomografia continua sendo o exame de escolha para os quadros de OMCC com sensibilidade de 90% para fĂstulas labirĂnticas. Nas fĂstulas grau II a cirurgia apresenta bom resultado funcional.Universidade Federal de SĂŁo Paulo (UNIFESP) Escola Paulista de Medicina Departamento de Otorrinolaringologia e DistĂșrbios da Comunicação HumanaUNIFESP, EPM, Depto. de Otorrinolaringologia e DistĂșrbios da Comunicação HumanaSciEL
Observation of Parity Violation in the Omega-minus -> Lambda + K-minus Decay
The alpha decay parameter in the process Omega-minus -> Lambda + K-minus has
been measured from a sample of 4.50 million unpolarized Omega-minus decays
recorded by the HyperCP (E871) experiment at Fermilab and found to be [1.78 +/-
0.19(stat) +/- 0.16(syst)]{\times}10^{-2}. This is the first unambiguous
evidence for a nonzero alpha decay parameter, and hence parity violation, in
the Omega-minus -> Lambda + K-minus decay.Comment: 10 pages, 7 figure
HyperCP: A high-rate spectrometer for the study of charged hyperon and kaon decays
The HyperCP experiment (Fermilab E871) was designed to search for rare
phenomena in the decays of charged strange particles, in particular CP
violation in and hyperon decays with a sensitivity of
. Intense charged secondary beams were produced by 800 GeV/c protons
and momentum-selected by a magnetic channel. Decay products were detected in a
large-acceptance, high-rate magnetic spectrometer using multiwire proportional
chambers, trigger hodoscopes, a hadronic calorimeter, and a muon-detection
system. Nearly identical acceptances and efficiencies for hyperons and
antihyperons decaying within an evacuated volume were achieved by reversing the
polarities of the channel and spectrometer magnets. A high-rate
data-acquisition system enabled 231 billion events to be recorded in twelve
months of data-taking.Comment: 107 pages, 45 Postscript figures, 14 tables, Elsevier LaTeX,
submitted to Nucl. Instrum. Meth.
Observations of glyoxal and formaldehyde as metrics for the anthropogenic impact on rural photochemistry
We present simultaneous fast, in-situ measurements of formaldehyde and glyoxal from two rural campaigns, BEARPEX 2009 and BEACHON-ROCS, both located in Pinus Ponderosa forests with emissions dominated by biogenic volatile organic compounds (VOCs). Despite considerable variability in the formaldehyde and glyoxal concentrations, the ratio of glyoxal to formaldehyde, R<sub>GF</sub>, displayed a very regular diurnal cycle over nearly 2 weeks of measurements. The only deviations in R<sub>GF</sub> were toward higher values and were the result of a biomass burning event during BEARPEX 2009 and very fresh anthropogenic influence during BEACHON-ROCS. Other rapid changes in glyoxal and formaldehyde concentrations have hardly any affect on R<sub>GF</sub> and could reflect transitions between low and high NO regimes. The trend of increased R<sub>GF</sub> from both anthropogenic reactive VOC mixtures and biomass burning compared to biogenic reactive VOC mixtures is robust due to the short timescales over which the observed changes in R<sub>GF</sub> occurred. Satellite retrievals, which suggest higher R<sub>GF</sub> for biogenic areas, are in contrast to our observed trends. It remains important to address this discrepancy, especially in view of the importance of satellite retrievals and in situ measurements for model comparison. In addition, we propose that R<sub>GF</sub> represents a useful metric for biogenic or anthropogenic reactive VOC mixtures and, in combination with absolute concentrations of glyoxal and formaldehyde, furthermore represents a useful metric for the extent of anthropogenic influence on overall reactive VOC processing via NO<sub>x</sub>. In particular, R<sub>GF</sub> yields information about not simply the VOCs dominating reactivity in an airmass, but the VOC processing itself that is directly coupled to ozone and secondary organic aerosol production
Spatial regulation of the glycocalyx component podocalyxin is a switch for prometastatic function
The glycocalyx component and sialomucin podocalyxin (PODXL) is required for normal tissue development by promoting apical membranes to form between cells, triggering lumen formation. Elevated PODXL expression is also associated with metastasis and poor clinical outcome in multiple tumor types. How PODXL presents this duality in effect remains unknown. We identify an unexpected function of PODXL as a decoy receptor for galectin-3 (GAL3), whereby the PODXL-GAL3 interaction releases GAL3 repression of integrin-based invasion. Differential cortical targeting of PODXL, regulated by ubiquitination, is the molecular mechanism controlling alternate fates. Both PODXL high and low surface levels occur in parallel subpopulations within cancer cells. Orthotopic intraprostatic xenograft of PODXL-manipulated cells or those with different surface levels of PODXL define that this axis controls metastasis in vivo. Clinically, interplay between PODXL-GAL3 stratifies prostate cancer patients with poor outcome. Our studies define the molecular mechanisms and context in which PODXL promotes invasion and metastasis
Deep exclusive electroproduction off the proton at CLAS
The exclusive electroproduction of above the resonance region was
studied using the Large Acceptance Spectrometer () at
Jefferson Laboratory by scattering a 6 GeV continuous electron beam off a
hydrogen target. The large acceptance and good resolution of ,
together with the high luminosity, allowed us to measure the cross section for
the process in 140 (, , ) bins:
, 1.6 GeV GeV and 0.1 GeV
GeV. For most bins, the statistical accuracy is on the order of a few
percent. Differential cross sections are compared to two theoretical models,
based either on hadronic (Regge phenomenology) or on partonic (handbag diagram)
degrees of freedom. Both can describe the gross features of the data reasonably
well, but differ strongly in their ingredients. If the handbag approach can be
validated in this kinematical region, our data contain the interesting
potential to experimentally access transversity Generalized Parton
Distributions.Comment: 18pages, 21figures,2table
Horizontal Branch Stars: The Interplay between Observations and Theory, and Insights into the Formation of the Galaxy
We review HB stars in a broad astrophysical context, including both variable
and non-variable stars. A reassessment of the Oosterhoff dichotomy is
presented, which provides unprecedented detail regarding its origin and
systematics. We show that the Oosterhoff dichotomy and the distribution of
globular clusters (GCs) in the HB morphology-metallicity plane both exclude,
with high statistical significance, the possibility that the Galactic halo may
have formed from the accretion of dwarf galaxies resembling present-day Milky
Way satellites such as Fornax, Sagittarius, and the LMC. A rediscussion of the
second-parameter problem is presented. A technique is proposed to estimate the
HB types of extragalactic GCs on the basis of integrated far-UV photometry. The
relationship between the absolute V magnitude of the HB at the RR Lyrae level
and metallicity, as obtained on the basis of trigonometric parallax
measurements for the star RR Lyrae, is also revisited, giving a distance
modulus to the LMC of (m-M)_0 = 18.44+/-0.11. RR Lyrae period change rates are
studied. Finally, the conductive opacities used in evolutionary calculations of
low-mass stars are investigated. [ABRIDGED]Comment: 56 pages, 22 figures. Invited review, to appear in Astrophysics and
Space Scienc
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