3,068 research outputs found

    Improvement of Unconfined Compressive Strength of Natural Organic Soil

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    The aim of this paper is to investigate the possible improvement of unconfined compressive strength of natural organic soil by using cement dust and fly ash. Natural organic soil with different percentage of organic content (0, 5, 10.15 and 20 %) is used. Three different percentages of cement dust and fly ash (3, 6 and 9 %) are used to improve the strength characteristics of the organic soil. The effect of curing time is investigates. The result show that unconfined compressive strength of organic soil decreased with increasing the organic content. The addition of cement dust increased the unconfined compressive strength for all percentage of organic content, while the addition of fly ash improved the strength characteristics of organic soil for samples with organic content greater than 10 %. Keywords: organic content, unconfined compressive strength, cement dust, fly ash

    The effects of the ambient liquid medium on the ablation efficiency, size and stability of silver nanoparticles prepared by pulse laser ablation in liquid technique

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    Silver (Ag) nanoparticles (NPs) were synthesized by pulsed laser (Nd:YAG, 1064 nm) ablation of individual target in various solutions. The influence of deionized water (DIW), ethanol and Polyvinylpyrrolidone (PVP) as ambient medium on the fundamental aspects such as ablation efficiency, particle size and stability of Ag NPs was studied. UV-vis spectrophotometer and transmission electron microscopy (TEM) were used to study the optical characterization and morphological analysis of all the synthesized samples, respectively. Preparation in DIW was carried out as a reference sample. The experiments demonstrated that ablation efficiency and stability of NPs in ethanol medium are lowest than those prepared in PVP medium and the reference sample. PVP medium led to higher stability, lower ablation efficiency and finer average particle size compared to reference sample

    Prostate cancer metastases to the rectum: A case report

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    Prostate cancer rarely metastasis to the rectum. Findings in the patient reported here emphasize the importance of the relationship between urinary and gastrointestinal symptoms in detecting prostatic neoplasms in older male patients

    The VIMOS Public Extragalactic Redshift Survey (VIPERS). Exploring the dependence of the three-point correlation function on stellar mass and luminosity at 0.5<z<1.1

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    The three-point correlation function (3PCF) is a powerful probe to investigate the clustering of matter in the Universe in a complementary way with respect to lower-order statistics, providing additional information with respect to the two-point correlation function and allowing us to shed light on biasing, nonlinear processes, and deviations from Gaussian statistics. In this paper, we analyse the first data release of the VIMOS Public Extragalactic Redshift Survey (VIPERS), determining the dependence of the three-point correlation function on luminosity and stellar mass at z=[0.5,1.1]z=[0.5,1.1]. We exploit the VIPERS Public Data Release 1, consisting of more than 50,000 galaxies with B-band magnitudes in the range 21.6MB5log(h)19.9-21.6\lesssim M_{\rm B}-5\log(h)\lesssim-19.9 and stellar masses in the range 9.8log(M[h2M])10.79.8\lesssim\log(M_\star[h^{-2}\,M_\odot])\lesssim 10.7. We measure both the connected 3PCF and the reduced 3PCF in redshift space, probing different configurations and scales, in the range 2.5<r2.5<r\,[Mpc/h]<20<20. We find a significant dependence of the reduced 3PCF on scales and triangle shapes, with stronger anisotropy at larger scales (r10r\sim10 Mpc/h) and an almost flat trend at smaller scales, r2.5r\sim2.5 Mpc/h. Massive and luminous galaxies present a larger connected 3PCF, while the reduced 3PCF is remarkably insensitive to magnitude and stellar masses in the range we explored. These trends, already observed at low redshifts, are confirmed for the first time to be still valid up to z=1.1z=1.1, providing support to the hierarchical scenario for which massive and bright systems are expected to be more clustered. The possibility of using the measured 3PCF to provide independent constraints on the linear galaxy bias bb has also been explored, showing promising results in agreement with other probes.Comment: 12 pages, 11 figures, 2 tables, accepted for publication in A&

    Binary optical communication in single-mode and entangled quantum noisy channels

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    We address binary optical communication in single-mode and entangled quantum noisy channels. For single-mode we present a systematic comparison between direct photodetection and homodyne detection in realistic conditions, i.e. taking into account the noise that occurs both during the propagation and the detection of the signals. We then consider entangled channels based on twin-beam state of radiation, and show that with realistic heterodyne detection the error probability at fixed channel energy is reduced in comparison to the single-mode cases for a large range of values of quantum efficiency and noise parameters

    The VIMOS Public Extragalactic Redshift Survey (VIPERS): PCA-based automatic cleaning and reconstruction of survey spectra

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    Identifying spurious reduction artefacts in galaxy spectra is a challenge for large surveys. We present an algorithm for identifying and repairing residual spurious features in sky-subtracted galaxy spectra with application to the VIPERS survey. The algorithm uses principal component analysis (PCA) applied to the galaxy spectra in the observed frame to identify sky line residuals imprinted at characteristic wavelengths. We further model the galaxy spectra in the rest-frame using PCA to estimate the most probable continuum in the corrupted spectral regions, which are then repaired. We apply the method to 90,000 spectra from the VIPERS survey and compare the results with a subset where careful editing was performed by hand. We find that the automatic technique does an extremely good job in reproducing the time-consuming manual cleaning and does it in a uniform and objective manner across a large data sample. The mask data products produced in this work are released together with the VIPERS second public data release (PDR-2).Comment: Find the VIPERS data release at http://vipers.inaf.i

    Awareness of Final-Year Medical Students of Omdurman Islamic University on Their Career Choices

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    Background: Medical students undergo a complex process as a student to make a career decision and pursue further specialization. This study explores the factors that influence the career choices of the two genders studying in the final year of medicine at Omdurman Islamic University.Methods: This institution-based cross-sectional study was conducted on 194 male and female fifth-year medical students studying at Omdurman Islamic University. The questionnaire contains 15 multiple-choice questions to determine the factors affecting students’ career choices – lifestyle, income, family impact,…etc. – and the association between gender and the specialties they choose to pursue.Results: The specialties were preferred in the following order: surgery by 22.9%, internal medicine by 18.3%, obstetric gynecology by 13.8%, and pediatric by 10% (limited to the four major specialties). The least chosen specialties were histopathology, emergency medicine, psychiatry, and anesthesia (all were 0.9%). Family medicine and forensics were not chosen by any participant. Females significantly preferred dermatology, obstetrics and gynecology, otolaryngology, and pediatrics compared to their male counterparts. Whereas, males compared to females significantly preferred orthopedics and surgery. The factors influencing change in students’ specialties based on their gender were family views and family obligations. Nearly 80% of students choose a career based on personal interest; lifestyle and financial reward were also seen to play an important role in choosing a specialty. About 91% of participants agreed that there is a need for guidance. A great proportion of final-year students (62%) preferred to specialize abroad and related it to a good lifestyle and financial stability.Conclusion: This study showed that the students’ awareness about specialty choices was limited to certain specialties as seen in the literature. The most preferred specialties were surgery (22.9%), internal medicine (18.3%), obstetrics and gynecology (13.8%), and pediatric (10%). There are many factors influencing the selection of specialties, however, the most common one is personal interest followed by lifestyle issues and financial reward. Additionally, there is a significant gender difference in career-choice decisions

    The VIMOS Public Extragalactic Redshift Survey (VIPERS): On the correct recovery of the count-in-cell probability distribution function

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    We compare three methods to measure the count-in-cell probability density function of galaxies in a spectroscopic redshift survey. From this comparison we found that when the sampling is low (the average number of object per cell is around unity) it is necessary to use a parametric method to model the galaxy distribution. We used a set of mock catalogues of VIPERS, in order to verify if we were able to reconstruct the cell-count probability distribution once the observational strategy is applied. We find that in the simulated catalogues, the probability distribution of galaxies is better represented by a Gamma expansion than a Skewed Log-Normal. Finally, we correct the cell-count probability distribution function from the angular selection effect of the VIMOS instrument and study the redshift and absolute magnitude dependency of the underlying galaxy density function in VIPERS from redshift 0.50.5 to 1.11.1. We found very weak evolution of the probability density distribution function and that it is well approximated, independently from the chosen tracers, by a Gamma distribution.Comment: 14 pages, 11 figures, 2 table

    The VIMOS Public Extragalactic Survey (VIPERS): First Data Release of 57 204 spectroscopic measurements

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    We present the first Public Data Release (PDR-1) of the VIMOS Public Extragalactic Survey (VIPERS). It comprises 57 204 spectroscopic measurements together with all additional information necessary for optimal scientific exploitation of the data, in particular the associated photometric measurements and quantification of the photometric and survey completeness. VIPERS is an ESO Large Programme designed to build a spectroscopic sample of ' 100 000 galaxies with iAB < 22.5 and 0.5 < z < 1.5 with high sampling rate (~45%). The survey spectroscopic targets are selected from the CFHTLS-Wide five-band catalogues in the W1 and W4 fields. The final survey will cover a total area of nearly 24 deg2, for a total comoving volume between z = 0.5 and 1.2 of ~4x10^7 h^(-3)Mpc^3 and a median galaxy redshift of z~0.8. The release presented in this paper includes data from virtually the entire W4 field and nearly half of the W1 area, thus representing 64% of the final dataset. We provide a detailed description of sample selection, observations and data reduction procedures; we summarise the global properties of the spectroscopic catalogue and explain the associated data products and their use, and provide all the details for accessing the data through the survey database (http://vipers.inaf.it) where all information can be queried interactively.Comment: Accepted for publication in A&A Added and/or replaced some figure, added section on DataBase interface, expaned Introductio

    The VIMOS Public Extragalactic Redshift Survey (VIPERS): A quiescent formation of massive red-sequence galaxies over the past 9 Gyr

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    We explore the evolution of the Colour-Magnitude Relation (CMR) and Luminosity Function (LF) at 0.4<z<1.3 from the VIMOS Public Extragalactic Redshift Survey (VIPERS) using ~45,000 galaxies with precise spectroscopic redshifts down to i'_AB<22.5 over ~10.32 deg^2 in two fields. From z=0.5 to z=1.3 the LF and CMR are well defined for different galaxy populations and M^*_B evolves by ~1.04(1.09)+/-0.06(0.10) mag for the total (red) galaxy sample. We compare different criteria for selecting early-type galaxies (ETGs): (1) fixed cut in rest-frame (U-V) colours, (2) evolving cut in (U-V) colours, (3) rest-frame (NUV-r')-(r'-K) colour selection, and (4) SED classification. Regardless of the method we measure a consistent evolution of the red-sequence (RS). Between 0.4<z<1.3 we find a moderate evolution of the RS intercept of Delta(U-V)=0.28+/-0.14 mag, favouring exponentially declining star formation (SF) histories with SF truncation at 1.7<=z<=2.3. Together with the rise in the ETG number density by 0.64 dex since z=1, this suggests a rapid build-up of massive galaxies (M>10^11 M_sun) and expeditious RS formation over a short period of ~1.5 Gyr starting before z=1. This is supported by the detection of ongoing SF in ETGs at 0.9<z<1.0, in contrast with the quiescent red stellar populations of ETGs at 0.5<z<0.6. There is an increase in the observed CMR scatter with redshift, two times larger than in galaxy clusters and at variance with theoretical models. We discuss possible physical mechanisms that support the observed evolution of the red galaxy population. Our findings point out that massive galaxies have experienced a sharp SF quenching at z~1 with only limited additional merging. In contrast, less-massive galaxies experience a mix of SF truncation and minor mergers which build-up the low- and intermediate-mass end of the CMR.Comment: 27 pages, 21 figures, accepted for publication in A&
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