345 research outputs found
On DBI Textures with Generalized Hopf Fibration
In this letter we show numerical existence of O(4) Dirac-Born-Infeld (DBI)
Textures living in (N +1) dimensional spacetime. These defects are
characterized by mapping, generalizing the well-known Hopf
fibration into ?, for all N > 3. The nonlinear nature of DBI
kinetic term provides stability against size perturbation and thus renders the
defects having natural scale.Comment: Accepted for publication in Phys.Lett.
Comprehensive aerodynamic and dynamic study of independence of ukraine monument
Розглянуто результати комплексних досліджень вирішення інженерної проблеми створення висотного монумента колонного типу в Києві, динамічних досліджень моделі в масштабі 1:25 та аеродинамічних досліджень великомасштабної моделі (1:8) в аеродинамічній трубі ТАД-2 Національного авіаційного університету. Наведено процедуру визначення на натурному об’єкті реальних динамічних характеристик та забезпечення ефективності демпфіруванняРассмотрены результаты комплексных исследований решения инженерной задачи создания высотного монумента колонного типа в Киеве, динамических исследований модели в масштабе 1:25 и аэродинамических испытаний крупномасштабной (1:8) модели в аэродинамической трубе ТАД-2 Национального авиационного университета. Приведена процедура определения на натурном объекте реальных динамических характеристик и обеспечения эффективности демпфированияComprehensive approach for solution the engineering problems o f creation the high-rise extended pillartype Monument in Kiyv is described. The results o f dynamic tests o f 1:25 scale model and aerodynamictests o f 1:8 scale model o f the Monument in TAD-2 wind tunnel are given. The procedures fordetermination o f actual dynamic characteristics and assurance the efficiency o f damping on the siteare describe
Використання вимог сучасної стандартизації на харчових підприємствах
The paper investigates the implementation of the HACCP system (Hazard Analysis and Critical Control Points) in the restaurant business. Restaurant facilities produce not only culinary products, but also a variety of bakery, flour confectionery and confectionery products, which leads to an increase in the used raw materials and, accordingly, an increase in a variety of technological processes for processing these raw materials. Restaurant business establishments include restaurants, pastry shops, cafes, bars, snack bars, canteens, buffets, kiosks and other fast food and drink establishments. Until September 20, 2019, all Ukrainian food industry enterprises providing food services, as well as food suppliers and carriers, were required to implement the HACCP food safety management system. The implementation of the HACCP system in restaurant business establishments is a difficult process that concerns all services and all personnel, because it is necessary not only to create an appropriate service, develop documentation and an algorithm for performing all procedures, review technological processes, equipment, raw material suppliers, but also train personnel comply with the new operating rules. The paper analyzes the factors of potential pollution: physical, chemical and biological and their influence on the quality of the final product. Each of these three factors are monitored at all stages of production, that is, manufacturers comply with fundamentally new rules in food production. For each stage, its own critical control point is defined and recommended, at which the products are tested to ensure product quality. The paper presents a list of basic and operational documentation of the HACCP system, which must be used in restaurants. All enterprises whose activities are related to food products are trying to implement the HACCP system, not only because it will allow domestic producers to comply with the requirements of domestic legislation, but also because it will give consumers confidence that the products they real high qualityand absolutely safe for health.У роботі досліджується впровадження системи НАССР (Hazard Analysis and Critical Control Points) у закладах ресторанного бізнесу. В закладах ресторанного господарства виробляють не тільки кулінарну продукцію, а й різноманітні хлібобулочні, борошняні кондитерські та кондитерські вироби, що веде до збільшення сировини, яка використовується та відповідно до збільшення різноманітних технологічних процесів з переробки цієї сировини. До закладів ресторанного бізнесу можна зарахувати ресторани, кондитерські, кафе, бари, закусочні, їдальні, буфети, кіоски та інші заклади швидкого приготування їжі та напоїв. До 20 вересня 2019 року всі українські підприємства харчової галузі, які надають послуги з харчування, а також постачальники та перевізники харчових продуктів мали впровадити систему управління безпечністю харчування НАССР. Впровадження системи НАССР у закладах ресторанного бізнесу – важкий процес, який стосується всіх служб і всього персоналу, тому що необхідно не тільки створити відповідну службу, розробити документацію та алгоритм виконання всіх процедур, провести перегляд технологічних процесів, устаткування, постачальників сировини, а й навчити персонал дотримуватися нових правил роботи. проведено аналіз факторів потенційного забруднення: фізичного, хімічного і біологічного та їхнього впливу на якість кінцевого продукту харчування. Кожен з цих трьох факторів відстежується на всіх етапах виробництва, тобто виробники дотримуються принципово нових правил у виробництві продуктів харчування. Для кожного етапу визначена та рекомендована своя критична точка контролю, на якій продукція проходить контроль для забезпечення відповідної якості продукції. В роботі представлений перелік базової та оперативної документації системи НАССР, яку потрібно використовувати у закладах ресторанного господарства. Всі підприємства, діяльність яких пов’язана із продуктами харчування, намагаються впровадити систему HACCP не тільки тому, що це дозволить вітчизняним виробникам виконати вимоги вітчизняного законодавства а й тому, що це додасть впевненості споживачам, що продукція, яку вони купують, дійсно високої якості і абсолютно безпечна для здоров’я
Existence and large time behavior for generalized Kelvin-Voigt equations governing nonhomogeneous and incompressible fluids
Generalized Kelvin-Voigt equations governing nonhomogeneous and incompressible
fluids are considered in this work. We assume that, in the momentum equation, the diffusion
and relaxation terms are described by two distinct power-laws. Moreover, we assume that the
momentum equation is perturbed by an extra term, which, depending on whether its signal is
positive or negative, may account for the presence of a source or a sink within the system. For
the associated initial-boundary value problem, we study the existence of weak solutions as well
as the large time behavior of the solutions.Portuguese Foundation for Science and Technology: UID/MAT/04561/2019info:eu-repo/semantics/publishedVersio
Towards a resource-based habitat approach for spatial modelling of vector-borne disease risks
Given the veterinary and public health impact of vector-borne diseases, there is a clear need to assess the suitability of landscapes for the emergence and spread of these diseases. Current approaches for predicting disease risks neglect key features of the landscape as components of the functional habitat of vectors or hosts, and hence of the pathogen. Empirical–statistical methods do not explicitly incorporate biological mechanisms, whereas current mechanistic models are rarely spatially explicit; both methods ignore the way animals use the landscape (i.e. movement ecology). We argue that applying a functional concept for habitat, i.e. the resource-based habitat concept (RBHC), can solve these issues. The RBHC offers a framework to identify systematically the different ecological resources that are necessary for the completion of the transmission cycle and to relate these resources to (combinations of) landscape features and other environmental factors. The potential of the RBHC as a framework for identifying suitable habitats for vector-borne pathogens is explored and illustrated with the case of bluetongue virus, a midge-transmitted virus affecting ruminants. The concept facilitates the study of functional habitats of the interacting species (vectors as well as hosts) and provides new insight into spatial and temporal variation in transmission opportunities and exposure that ultimately determine disease risks. It may help to identify knowledge gaps and control options arising from changes in the spatial configuration of key resources across the landscape. The RBHC framework may act as a bridge between existing mechanistic and statistical modelling approaches
Ancient stars beyond the Local Group: RR Lyrae variables and Blue Horizontal Branch stars in Sculptor Group Dwarf Galaxies
We have used Hubble Space Telescope ACS images to generate color-magnitude
diagrams that reach below the magnitude of the horizontal branch in the
Sculptor Group dwarf galaxies ESO294-010 and ESO410-005. In both diagrams blue
horizontal branch stars are unambiguously present, a signature of the existence
of an ancient stellar population whose age is comparable to that of the
Galactic halo globular clusters. The result is reinforced by the discovery of
numerous RR Lyrae variables in both galaxies. The occurrence of these stars in
the first direct confirmation of the existence of ancient stellar populations
beyond the Local Group and indicates that star formation can occur at the
earliest epochs even in low density environments.Comment: 11 pages, 2 figures, accepted for publication in Astrophysical
Journal Letter
The magnetic field and geometry of the oblique shock in the jet of 3C 346
We investigate the brightest regions of the kpc-scale jet in the powerful
radio galaxy 3C 346, using new optical HST ACS/F606W polarimetry together with
Chandra X-ray data and 14.9 GHz and 22.5 GHz VLA radio polarimetry. The jet
shows a close correspondence in optical and radio morphology, while the X-ray
emission shows an 0.80 +/- 0.17 kpc offset from the optical and radio peak
positions. Optical and radio polarimetry show the same apparent magnetic field
position angle and fractional polarization at the brightest knot, where the jet
undergoes a large kink of almost 70 degrees in the optical and radio images.
The apparent field direction here is well-aligned with the new jet direction,
as predicted by earlier work that suggested the kink was the result of an
oblique shock. We have explored models of the polarization from oblique shocks
to understand the geometry of the 3C 346 jet, and find that the upstream flow
is likely to be highly relativistic (0.91 +0.05 / -0.07 c), where the plane of
the shock front is inclined at an angle of 51 (+/- 11) degrees to the upstream
flow which is at an angle 14 (+8 / -7) degrees to our line of sight. The actual
deflection angle of the jet in this case is only 22 degrees.Comment: 11 pages, 5 figures. Accepted by MNRA
Morphological Composition of z~0.4 groups: The site of S0 formation
The low redshift Universe (z<~0.5) is not a dull place. Processes leading to
the suppression of star formation and morphological transformation are
prevalent: this is particularly evident in the dramatic upturn in the fraction
of S0-type galaxies in clusters. However, until now, the process and
environment of formation has remained unidentified. We present a HST-based
morphological analysis of galaxies in the redshift-space selected group and
field environments at z~0.4. Groups contain a much higher fraction of S0s at
fixed luminosity than the lower density field, with >99.999% confidence. Indeed
the S0 fraction in groups is at least as high as in z~0.4 clusters and X-ray
selected groups, which have more luminous Intra Group Medium (IGM). An 97%
confident excess of S0s at >=0.3Mpc from the group centre at fixed luminosity,
tells us that formation is not restricted to, and possibly even avoids, the
group cores. Interactions with a bright X-ray emitting IGM cannot be important
for the formation of the majority of S0s in the Universe. In contrast to S0s,
the fraction of elliptical galaxies in groups at fixed luminosity is similar to
the field, whilst the brightest ellipticals are strongly enhanced towards the
group centres (>99.999% confidence within 0.3Mpc). We conclude that the group
and sub-group environments must be dominant for the formation of S0 galaxies,
and that minor mergers, galaxy harassment and tidal interactions are the most
likely responsible mechanisms. This has implications not only for the inferred
pre-processing of cluster galaxies, but also for the global morphological and
star formation budget of galaxies: as hierarchical clustering progresses, more
galaxies will be subject to these transformations as they enter the group
environment.Comment: 13 pages, 6 figures. Accepted for publication in Ap
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