Online Admission Control and Embedding of Service Chains

The virtualization and softwarization of modern computer networks enables the definition and fast deployment of novel network services called service chains: sequences of virtualized network functions (e.g., firewalls, caches, traffic optimizers) through which traffic is routed between source and destination. This paper attends to the problem of admitting and embedding a maximum number of service chains, i.e., a maximum number of source-destination pairs which are routed via a sequence of to-be-allocated, capacitated network functions. We consider an Online variant of this maximum Service Chain Embedding Problem, short OSCEP, where requests arrive over time, in a worst-case manner. Our main contribution is a deterministic O(log L)-competitive online algorithm, under the assumption that capacities are at least logarithmic in L. We show that this is asymptotically optimal within the class of deterministic and randomized online algorithms. We also explore lower bounds for offline approximation algorithms, and prove that the offline problem is APX-hard for unit capacities and small L > 2, and even Poly-APX-hard in general, when there is no bound on L. These approximation lower bounds may be of independent interest, as they also extend to other problems such as Virtual Circuit Routing. Finally, we present an exact algorithm based on 0-1 programming, implying that the general offline SCEP is in NP and by the above hardness results it is NP-complete for constant L.Comment: early version of SIROCCO 2015 pape

A Relationship between Gestational Age Determined by Ultrasound Biometric and Symphysis Fundal Height Measurements

Last Menstrual Period (LMP), Symphysis fundal height (SFH) or Ultrasound biometric measurements are being used to determine the gestational age (GA) and expected delivery date (EDD) by various ante-natal care (ANC) providers for pregnant women in both urban and rural areas. However, each method has its limitations in determining accurate gestational age of the fetus at different stages of gestation. Ultrasound facilities may not be readily available in some rural setups or may not be affordable for some pregnant women. Many have to depend on SFH measurements as actual LMP may not be remembered by the women when they visit ante-natal clinics. This study aims to establish a relationship between gestational age estimated by ultrasound biometric measurements and fundal height measurements to compute accurate gestational ages by measurement of fundal heights using 100 pregnant women. A non-linear regression equation was fitted from the measured data.  The relationship between the gestational age(wks) and the fundal height(cm) was obtained from the mathematical modeling of the data by the equation GESTATIONAL AGE(wks) = 9.166 e 0.039 (FUNDAL HEIGHT)(cm) with R2 = 0.931. Keywords: Gestational Age, Last menstrual age, Symphysis-fundal height, Ultrasoun

Italia-Svizzera : 1-0

Evolving online virtual worlds are intensely being utilised as 3D Virtual Learning Environments (3D VLEs) by hundreds of universities worldwide. However, there is inadequate academic research depicting satisfaction of users from the environmental design factors of 3D virtual buildings used within these virtual worlds. Specifically, there is no research evidence representing satisfaction of educational facilities’ users, namely students and faculty, from the architectural design characteristics of their 3D virtual university campuses. This research focuses explicitly on capturing the contentment levels of students towards specified variations of certain architectural design elements of the 3D virtual learning spaces, where educational sessions are conducted in 3D VLEs. This hence provides preliminary guidelines on how to enhance the design of these spaces to augment e-learning experiences of students within 3D VLEs; achieved by analysing survey results representing students’ opinions towards different architectural features of the learning spaces within different university 3D virtual campuses

Accounting for biological and physical sources of acoustic backscatter improves estimates of zooplankton biomass

Author Posting. © NRC Canada, 2008. This is the author's version of the work. It is posted here by permission of NRC Canada for personal use, not for redistribution. The definitive version was published in Canadian Journal of Fisheries and Aquatic Sciences 65 (2008): 1321-1333, doi:10.1139/F08-047.In order to convert measurements of backscattered acoustic energy to estimates of abundance and taxonomic information about the zooplankton community, all of the scattering processes in the water column need to be identified and their scattering contributions quantified. Zooplankton populations in the eastern edge of Wilkinson Basin in the Gulf of Maine in the Northwest Atlantic were surveyed in October 1997. Net tow samples at different depths, temperature and salinity profiles, and multiple frequency acoustic backscatter measurements from the upper 200 meters of the water column were collected. Zooplankton samples were identified, enumerated, and measured. Temperature and salinity profiles were used to estimate the amount of turbulent microstructure in the water column. These data sets were used with theoretical acoustic scattering models to calculate the contributions of both biological and physical scatterers to the overall measured scattering level. The output of these predictions shows that the dominant source of acoustic backscatter varies with depth and acoustic frequency in this region. By quantifying the contributions from multiple scattering sources, acoustic backscatter becomes a better measure of net-collected zooplankton biomass.This work was supported by the Office of Naval 540 Research (Grants #N00014-00-1-0052 and N00014-01-1-0166)

Coulomb correlations effects on localized charge relaxation in the coupled quantum dots

We analyzed localized charge time evolution in the system of two interacting quantum dots (QD) (artificial molecule) coupled with the continuous spectrum states. We demonstrated that Coulomb interaction modifies relaxation rates and is responsible for non-monotonic time evolution of the localized charge. We suggested new mechanism of this non-monotonic charge time evolution connected with charge redistribution between different relaxation channels in each QD.Comment: 10 pages, 10 figure

Predicting population responses to environmental change from individual-level mechanisms: towards a standardized mechanistic approach

Animal populations will mediate the response of global biodiversity to environmental changes. Population models are thus important tools for both understanding and predicting animal responses to uncertain future conditions. Most approaches, however, are correlative and ignore the individual-level mechanisms that give rise to population dynamics. Here, we assess several existing population modelling approaches, and find limitations to both ‘correlative’ and ‘mechanistic’ models. We advocate the need for a standardised mechanistic approach for linking individual mechanisms (physiology, behaviour and evolution) to population dynamics in spatially explicit landscapes. Such an approach is potentially more flexible and informative than current population models. Key to realising this goal, however, is overcoming current data limitations, the development and testing of eco-evolutionary theory to represent interactions between individual mechanisms, and standardised multidimensional environmental change scenarios which incorporate multiple stressors. Such progress is essential in supporting environmental decisions in uncertain future conditions

Light hadron and diquark spectroscopy in quenched QCD with overlap quarks on a large lattice

A simulation of quenched QCD with the overlap Dirac operator has been completed using 100 Wilson gauge configurations at beta = 6 on an 18^3 x 64 lattice and at beta = 5.85 on a 14^3 x 48 lattice, both in Landau gauge. We present results for light meson and baryon masses, meson final state "wave functions," and other observables, as well as some details on the numerical techniques that were used. Our results indicate that scaling violations, if any, are small. We also present an analysis of diquark correlations using the quark propagators generated in our simulation.Comment: 28 LaTeX pages, 41 figures, v2: minor updates, version published in JHE

Equilibrium and nonequilibrium fluctuations at the interface between two fluid phases

We have performed small-angle light-scattering measurements of the static structure factor of a critical binary mixture undergoing diffusive partial remixing. An uncommon scattering geometry integrates the structure factor over the sample thickness, allowing different regions of the concentration profile to be probed simultaneously. Our experiment shows the existence of interface capillary waves throughout the macroscopic evolution to an equilibrium interface, and allows to derive the time evolution of surface tension. Interfacial properties are shown to attain their equilibrium values quickly compared to the system's macroscopic equilibration time.Comment: 10 pages, 5 figures, submitted to PR

A macroscopic multifractal analysis of parabolic stochastic PDEs

It is generally argued that the solution to a stochastic PDE with multiplicative noise---such as $\dot{u}=\frac12 u"+u\xi$, where $\xi$ denotes space-time white noise---routinely produces exceptionally-large peaks that are "macroscopically multifractal." See, for example, Gibbon and Doering (2005), Gibbon and Titi (2005), and Zimmermann et al (2000). A few years ago, we proved that the spatial peaks of the solution to the mentioned stochastic PDE indeed form a random multifractal in the macroscopic sense of Barlow and Taylor (1989; 1992). The main result of the present paper is a proof of a rigorous formulation of the assertion that the spatio-temporal peaks of the solution form infinitely-many different multifractals on infinitely-many different scales, which we sometimes refer to as "stretch factors." A simpler, though still complex, such structure is shown to also exist for the constant-coefficient version of the said stochastic PDE.Comment: 41 page

Preliminary study of Hepatitis B surface antigen on mental health care workers at federal neuropsychiatric hospital Barnawa, Kaduna Nigeria

Background: This study was designed to determine retrospectively, HBsAg status, marker of HBV infection, among Mental Health Care Workers (MHCWs) at Federal Neuropsychiatric Hospital (FNPH), Barnawa Kaduna, North West, Nigeria. Two hundred and fifty one, apparently healthy HBV vaccine naïve, MHCWs, who voluntarily participate prior to HBV-vaccination. Materials and Methods: The screening was carried out using atlas latex haemagglutination test kit, between the months of December, 2000 through March, 2001. The MHCWs were categorized into senior and junior staff. Their ages, years of service, occupation, and department were obtained from year 2000 staff nominal roll. Prior to the study ethical approval was obtained from the hospital ethical committee. Two hundred and fifty one, participant were tested for HBsAg in a pre-HBV-vaccination exercise. Results: The number and percentages of participants by gender were 127 (50.6%) males and 124 (49.4%) females, respectively. The age range was 19-60 years with a mean age of 37 ± 2 years. The Number and percentages of junior and senior staff were 163 (65.0%) and 88 (35.0%), respectively. The incidence of HBsAg was 72 (28.7%). Incidence rates was highest among the males 41 (32.3%) compared to females 31(25.0%) and51-60yrs (50.0%), the incidence among Junior Staff was 52 (31.9%), while in Senior staff was 20 (22.7%) respectively. MHCWs who served between 26-30 years were 2 (66.7%) and those within 21-25 years were 6 (26.1%). Medical Record Staff were 3 (60.0%) and staff from other departments were Pharmacy 3 (50.0%), Artisans 7 (46.7%), Security 15(42.9%), Occupational Therapy Staff 2 (40.0%), Account Staff 6 (30.0%), Social Welfare 1 (25.0%), Hospital Maids 14 (23.7%), Administration Staff 11 (23.4%), Nurses 8 (17.0%), Medical Laboratory Staff 0 (0.0%), respectively. Statistical analysis obtained using Chisquare (x2) test showed no statistically significant association (p >0.05) between incidence of HBV-infection and years of service, Sex, Age, Cadre and Occupation. Conclusions: Due to a high prevalence of HbsAg, a marker of HBV infection, among MHCWs, Pre-vaccination screening should be instituted in Nigeria’s mental health facilities for early detection of HBV-infection and selective treatment. Key words: Hepatitis B virus; HbsAg; neuropsychiatric; vaccination; screening; Barnawa; Kaduna; Nigeria