1,098 research outputs found
Two-Face(s): ionized and neutral gas winds in the local Universe
We present a comprehensive study of the Na I 5890, 5895 (Na I D)
resonant lines in the Sloan Digital Sky Survey (SDSS, DR7) spectroscopic sample
to look for neutral gas outflows in the local galaxies. Individual galaxy
spectra are stacked in bins of M and SFR to investigate the dependence
of galactic wind occurrence and velocity as a function of the galaxy position
in the SFR- plane. In massive galaxies at the high SFR tail we find
evidence of a significant blue-shifted Na I D absorption, which we interpret as
evidence of neutral outflowing gas. The occurrence of the blue-shifted
absorption is observed at the same significance for purely SF galaxies, AGN and
composite systems at fixed SFR. In all classes of objects the blue-shift is the
largest and the Na I D equivalent width the smallest for face-on galaxies while
the absorption feature is at the systemic velocity for edge-on systems. This
indicates that the neutral outflow is mostly perpendicular or biconical with
respect to the galactic disk. We also compare the kinematics of the neutral gas
with the ionized gas phase as traced by the [OIII]5007, H,
[NII] and [NII] emission lines. Differently for the
neutral gas phase, all the emission lines show evidence of perturbed kinematics
only in galaxies with a significant level of nuclear activity and, they are
independent from the disk inclination. In conclusion, we find that, in the
local Universe, galactic winds show two faces which are related to two
different ejection mechanisms, namely the neutral outflowing gas phase related
to the SF activity along the galaxy disk and the ionized phase related to the
AGN feedback. In both the neutral and ionized gas phases, the observed wind
velocities suggest that the outflowing gas remains bound to the galaxy with no
definitive effect on the gas reservoir.Comment: Accepted to A&A, 13 pages, 9 figure
Migration and processes of cultural interaction. Outcomes from the Italian geographical research and study opportunities facing Metropolis 2014
The weak ring of the chain: Immigrants facing the economic crisis in Italy
The article offers a synthetic overview of the main effects that the international economic crisis has had on immigrants in Italy. After a brief introductory explanation of the main characteristics of the Italian context of immigration, the authors concentrate on two main problems: the immigrants\u2019 access to the labour market and to the housing system. The so-called \u201csocial vulnerability\u201d of migrants was increased by the tensions related to the economic crisis. The growing problems that immigrants have been facing in the last three years are linked to the territorial distribution and to the mobility of the migrant communities on the national territory. The tendency to a progressive redistribution of the migratory destinations and to an increased mobility within and outside the Italian national borders are among the consequences of the socio-economic difficulties suffered by migrants. Finally, a few conclusive remarks suggest some policy recommendations
Finite elements prediction of thermal stresses in work roll of hot rolling mills
AbstractA simplified numerical approach based on finite elements to compute thermal stresses occurring in work roll of hot rolling mills is here proposed. To decrease both the complexity of the analysis and the computational effort, this approach implements a plane finite element model of the work roll alone, loaded on its surface by the rotating thermal actions due to the cyclic sequence of the conductive heating caused by the contact with hot strip and cooling provided by water jets. Results from thermal analysis are preliminary compared to an analytical solution available in the literature and then applied as thermal input in the subsequent mechanical finite elements simulations, which provide thermal stress in the work roll and the elastic-plastic evolution of elements, close to the work roll surface
Systems Engineering and Its Application to Industrial Product Development
PREFACE : Mastering the complexity of innovative systems currently looks a challenging goal of design and product development as well as embedding a suitable degree of smartness in devices, machines and equipment to make them able of adapting their operation to variable conditions or effects of a harsh environment. This goal is achieved through a continuous monitoring of the system in service, an effec-tive control of its behavior and a wide connectivity towards many other systems. Only an effective system design and manufacture, able to cover all the required actions, can assure this kind of assessment overall the life cycle since a very ear-ly concept of the product to a full disposal and service.
Complexity makes hard managing the product development, because of the number of functions, subsystems, components and related interfaces usually in-volved, like in motor vehicles, robots, railways systems, aircrafts and spacecrafts as well as in large industrial manufacturing systems or very innovative microsys-tems and bioinspired devices. A crucial issue in this activity is performing a bright and complete elicitation of requirements, which need to be fully and suit-ably allocated to the system components, through a clear traceability, especially in systems produced as a result of material processing and assembling of parts. Moreover, the product must fit the requirements associated to some customer needs, innovation targets, and technical standards and be compatible with the manufacturer’s capabilities.
As it looks clear from the current state–of–art, since several years the Systems Engineering assures a suitable answer to the needs above mentioned. It provides a methodology to drive the product lifecycle assessment that is implemented through a well defined process, being based on some specific and graphical lan-guages and even formalized in several tools enabling the required analyses, tak-ing advantage of the capabilities of some dedicated commercial software. Those contents lead to create a platform, consisting of a sort of tools chain, which might be used and shared among different industrial and professional partners to digitalize both the information and even the whole industrial product develop-ment, as far as the current strategy referred to as “Industry 4.0 / The Factory of the Future” brightly suggests and supports. The so–called Model Based Systems Engineering (MBSE) is then successfully proposing an effective and modern al-ternative to the document-based approach, using data models as a main element of the design process. Some technical standards already drive the user in imple-menting the Systems Engineering, thus leading to develop a systematic approach the design aimed at satisfying the customer needs. Suitable capabilities in the manufactured system are assured by the so–called architectural frameworks, which support the system development and integration.
The Model Based Systems Engineering allows proceeding with a modeling activity which investigates requirements, behavior and architecture through a combined operational, functional and logical analysis, being linked and interop-erated with a mathematical and physical modeling, which is typically more known and widely used within the industrial engineering. A full integration of all the activities of the Product Lifecycle Management (PLM) is currently going on, to include the system architecture definition and its Application Lifecycle Man-agement (ALM) as well as the Product Data Management (PDM), i.e. the design activity together with the tasks of production, testing, homologation and service. A recognized standard certification to qualify the Systems Engineer is even available as the International Council on Systems Engineering (INCOSE) pro-vides.
The scenario above described is strongly integrated with the increasing devel-opment of both the network and the cyber–physical systems, for a fully distribut-ed connectivity, to be exploited in advanced smart systems and devices as well as in intelligent manufacturing, according to the most recent strategies of innova-tion as the “Industry 4.0” initiative and the “Lean manufacturing” idea. Simulta-neously, the system smartness and connectivity together increase the demand of data transmission and elaboration, thus linking this topic to the technology of big data management, whilst they benefit of the progress in information technology, through a secure cloud based on the network.
The context just described motivates the fast diffusion of the Model Based Systems Engineering as a tool for innovating all the production processes. The increasing demand of specialized software and of educational activities as well as the number of workshops and conferences focused on this topic confirm this trend. However, it might be remarked that several contributions to the literature about the Systems Engineering widely grew up during the last years, thus making the Reader sometimes confused, especially when approaching this topic at first.
The Systems Engineering topics are so many that it looks rather difficult mas-tering its skills, without a preliminary classification of contents. Technical do-mains involved are mainly those of engineering and computer science, although many other ones play the role of a daily user of this methodology. According to the most recent development of the Systems Engineering, whose typical applica-tion fields were the software and electronic systems even for space missions, the current focus consists of several industrial systems, being gradually innovated by introducing the tailored solutions of mechatronics. It is worthy noticing that a significant advancement was introduced between the very early implementation of the Systems Engineering and its recent evolution, since several new applica-tions are focused on the production of systems, which need to be manufactured through a material processing. Usually, they exhibit some attributes related both to their physical nature and to the functions performed, thus requiring to model both their functional and physical behaviors together. This need is changing the scenario of the typical applications of the Systems Engineering as software de-sign.
This handbook expressively avoids to cover all the typical contents of the spe-cialized literature of the Model Based Systems Engineering, whilst is aimed at making easier a first approach to this topic and sharing a preliminary experience performed by the authors within some industrial domains, by proceeding in the modeling activity in a real industrial environment. The main goal is drawing a sort of simple and hopefully clear roadmap in modeling and developing the in-dustrial and material systems and in implementing the Systems Engineering, par-ticularly in the design activity. Therefore, the target audience of this handbook includes professional engineers, scientists and students dealing with the Applica-tion Lifecycle Management and the system architecture assessment, more than the Product Data Management or the whole Product Lifecycle Management.
The approach followed is that of introducing some examples of implementa-tion of the Systems Engineering, by proceeding step by step from the screening of needs and the elicitation of requirements till a synthesis of the system design. Each action will be referred to the literature, related to the implementation of the Systems Modeling Language or SysML and to the use of some tools available on market, thus highlighting benefits, drawbacks and current limitations of some dedicated software or even of some proposed methodologies. Several comments will be provided to describe the troubles shared among some users of the Sys-tems Engineering as they were detected in daily practice by the authors. They wish that this handbook could briefly and gradually provide the Reader with a preliminary guideline to approach professionally the Model Based Systems En-gineering, by understanding its main contents and applying it to the industrial environment. As a desired result, this work might be considered as an integration of some textbooks of Machine Design, and it is aimed at completing the education within Engineering Design or at simply providing a friendly introduction to the Systems Engineerin
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Facebook Use Among African American and Hispanic Students: An Exploratory Investigation of Perceived Academic Impact
Facebook is one of the world’s leading social networking sites. It is pervasive in students’ lives and can impact their academic careers in a variety of ways. However, little research exists evaluating the use of Facebook in minority academic settings. An early step in this direction is to gain an understanding of how different student demographic groups use Facebook. An interest in further assessment of Facebook’s role in diverse segments of academia motivates the collection and analysis of Facebook-related data from minority serving institutions such as Historically Black Colleges or Universities (HBCUs) and Hispanic Serving Institutions (HSIs). This study presents the results of a comparative examination of African American students at an HBCU and Hispanic students at an HSI regarding their perceptions of Facebook use for academics. The findings reveal significant differences between the two groups. When compared to African American students, the Hispanic students use Facebook more for academics even though they perceive it to have a negative impact on academics. This perceived negative impact of Facebook is not directly translated into actual differences in self-reported GPA
Magellan Spectroscopy of AGN Candidates in the COSMOS Field
We present spectroscopic redshifts for the first 466 X-ray and radio-selected
AGN targets in the 2 deg^2 COSMOS field. Spectra were obtained with the IMACS
instrument on the Magellan (Baade) telescope, using the nod-and-shuffle
technique. We identify a variety of Type 1 and Type 2 AGN, as well as red
galaxies with no emission lines. Our redshift yield is 72% down to i_AB=24,
although the yield is >90% for i_AB<22. We expect the completeness to increase
as the survey continues. When our survey is complete and additional redshifts
from the zCOSMOS project are included, we anticipate ~1100 AGN with redshifts
over the entire COSMOS field. Our redshift survey is consistent with an
obscured AGN population that peaks at z~0.7, although further work is necessary
to disentangle the selection effects.Comment: 19 pages, 14 figures. Accepted to ApJS special COSMOS issue. The full
electronic version of Table 2 can be found at
http://shaihulud.as.arizona.edu/~jtrump/tab2.tx
A New Family of Multistep Methods with Improved Phase Lag Characteristics for the Integration of Orbital Problems
In this work we introduce a new family of ten-step linear multistep methods
for the integration of orbital problems. The new methods are constructed by
adopting a new methodology which improves the phase lag characteristics by
vanishing both the phase lag function and its first derivatives at a specific
frequency. The efficiency of the new family of methods is proved via error
analysis and numerical applications.Comment: 21 pages, 3 figures, 1 tabl
Prevalencia de Campylobacter jejuni y Campylobacter coli en carcasas de pollo procedentes de frigorĂficos, faena tradicional y kosher, y de locales de expendio
El objetivo del estudio fue determinar y comparar la prevalencia de Campylobacter jejuni y Campylobacter coli en carcasas de pollo obtenidas en frigorĂficos por faena convencional y kosher, y en locales de expendio. La prevalencia de Campylobacter spp. termotolerante fue del 94,0 (kosher) y del 32,0% (convencional) (p < 0,0001). La prevalencia de muestras contaminadas con C. jejuni, C. coli y con ambas especies fue del 36,0, del 2,0 y del 56,0% (Kosher) y del 26,0, del 4,0 y del 2,0% (convencional) (p < 0,0001), respectivamente. Se tomaron muestras de carcasas (n = 25) y superficies (tablas, n = 25; cuchilla, n = 25) en 25 locales. Los locales fueron categorizados como de riesgo alto (n = 11), moderado (n = 11) y bajo (n = 3). Diecinueve (76,0%) carcasas, 20 (80,0%) tablas y 18 (72,0%) cuchillas fueron positivas para Campylobacter spp. FrigorĂficos y locales fueron fuente de contaminaciĂłn de carcasas con Campylobacter spp. La prevalencia de Campylobacter spp. fue mayor en carcasas kosher. Campylobacter coli fue la especie más prevalente en carcasas de locales.We studied and compared the prevalence of Campylobacter jejuni and C. coliin chicken carcasses from conventional and kosher broiler abattoirs and retail stores. The prevalence of thermotolerant Campylobacter-positive carcasses was 94.0 (kosher) and 32.0% (conventional) (p < 0.0001), while the prevalence of samples contaminated with C. jejuni, C. coli and simultaneously with both species was 36.0, 2.0 and 56.0% (kosher) and 26.0, 4.0 and 2.0% (conventional) (p < 0.0001), respectively. Samples of chicken carcasses (n = 25) and food contact surfaces (tables, n = 25; knives, n = 25) from 25 retails were collected and risk quantification was performed. Retails were categorized as high-risk (n = 11), moderate-risk (n = 11) and low-risk (n = 3). Nineteen (76.0%) carcasses, 20 (80.0%) tables and 18 (72.0%) knives were Campylobacter-positive. Retails and abattoirs proved to be sources of carcass contamination with Campylobacter spp. Carcasses from kosher abattoirs were mostly contaminated with Campylobacter spp., whereas C. coli was the most prevalent species isolated from carcasses inretail stores.Fil: Guirin, Guillermo Federico. Laboratorio AGGA; ArgentinaFil: Brusa, Victoria. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico CONICET- La Plata. Instituto de GenĂ©tica Veterinaria "Ing. Fernando Noel Dulout". Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Instituto de GenĂ©tica Veterinaria; ArgentinaFil: Adriani, Cristian D.. Buenos Aires. Municipalidad de Berisso. Departamento de Seguridad Alimentaria; ArgentinaFil: Leotta, Gerardo Anibal. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico CONICET- La Plata. Instituto de GenĂ©tica Veterinaria "Ing. Fernando Noel Dulout". Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Instituto de GenĂ©tica Veterinaria; Argentin
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