899 research outputs found
The Standard Model and its Generalizations in Epstein-Glaser Approach to Renormalization Theory II: the Fermion Sector and the Axial Anomaly
We complete our study of non-Abelian gauge theories in the framework of
Epstein-Glaser approach to renormalization theory including in the model an
arbitrary number of Dirac Fermions. We consider the consistency of the model up
to the third order of the perturbation theory. In the second order we obtain
pure group theoretical relations expressing a representation property of the
numerical coefficients appearing in the left and right handed components of the
interaction Lagrangian. In the third order of the perturbation theory we obtain
the the condition of cancellation of the axial anomaly.Comment: 38 pages, LATEX 2e, extensive rewritting, some errors eliminate
Massive gravity from descent equations
Both massless and massive gravity are derived from descent equations
(Wess-Zumino consistency conditions). The massive theory is a continuous
deformation of the massless one.Comment: 8 pages, no figur
The Interaction of Quantum Gravity with Matter
The interaction of (linearized) gravitation with matter is studied in the
causal approach up to the second order of perturbation theory. We consider the
generic case and prove that gravitation is universal in the sense that the
existence of the interaction with gravitation does not put new constraints on
the Lagrangian for lower spin fields. We use the formalism of quantum off-shell
fields which makes our computation more straightforward and simpler.Comment: 25 page
On a Order Reduction Theorem in the Lagrangian Formalism
We provide a new proof of a important theorem in the Lagrangian formalism
about necessary and sufficient conditions for a second-order variational system
of equations to follow from a first-order Lagrangian.Comment: 9 pages, LATEX, no figures; appear in Il Nuovo Cimento
MODERN METHODS FOR FOOD PRODUCTS PRESERVATION
Bacteria, molds and yeasts are microorganisms that play an essential role in spoiling food. Food products preservation technologies are intended to reduce the intensity of the activity of pathogenic microorganisms that generate decomposition processes. From the point of view of food technologies, heat treatments (pasteurization, sterilization) are the main way of preserving food. The trend is to minimize or replace heat treatments with nonthermal, non-destructive methods, in order to preserve the freshness, nutritional and bioactive value of the food products. This paper presents the working principles and the effects of various modern methods of preservation, thermal and athermal, on food
Properties of the Scalar Universal Equations
The variational properties of the scalar so--called ``Universal'' equations
are reviewed and generalised. In particular, we note that contrary to earlier
claims, each member of the Euler hierarchy may have an explicit field
dependence. The Euler hierarchy itself is given a new interpretation in terms
of the formal complex of variational calculus, and is shown to be related to
the algebra of distinguished symmetries of the first source form.Comment: 15 pages, LaTeX articl
The moderating role of corporate reputation and employee-company identification on the work-related outcomes of job insecurity resulting from workforce localization policies
Although previous studies have examined the impact of job insecurity, there remains a need to understand specific issues related to job insecurity that results from government workforce localization policies. This study addresses this gap by examining employees' work-related outcomes: employee engagement, job burnout, and intentions to quit, recognizing the interplay of employees' identification with an organization and perceived corporate reputation in the context of Saudi Arabia's localization policies. The study uses social identification theory to explain how employees' perception of corporate reputation and their identification with a company shape their work attitudes in the presence of job-insecurity. Partial least square - path modeling (PLS-PM) and PROCESS tool is used to test hypotheses from data collected from 135 expatriate migrant employees working in different organizations in Saudi Arabia. Findings show that job insecurity has a significant effect of reducing the engagement of immigrant employees and leads to increased employee burnout and intentions to quit jobs. The results of moderation analysis show that favorable corporate reputation reduces the negative impact of job insecurity on employee's burnout and intentions to quit, whereas high level of identification with company may also reduce employee burnout, even during job insecurity. Although immigrant employees do not seek to leave a reputable organization due to localization policies, they still experience stress, become disengaged, and so are less productive. As a result, businesses should leverage their reputation towards governmental policies of localization, by advocating expatriate employees' contributions towards organizations and economy
TYPES OF ELECTRIC MOTOR CONTROLLERS THAT CAN BE USED ON AGRICULTURAL ELECTRIC TRACTORS
The development of electric propulsion systems has become a necessity for existing pollution regulations. This article presents a series of electric motor controllers that can be used on small or medium sized tractors. These controllers are easy to mount on tractors, do not require special mounting or positioning conditions, can be used with different types of electric motors and have a number of optional functions that can be activated depending on the chosen configuration. Controllers are intelligent enough to deal with the power or torque provided to the engine or change the way the engine works, switching it from engine to generator
STUDY ON THE CONVERSION OF A CONVENTIONAL TRACTOR INTO AN ELECTRIC TRACTOR
The paper presents the study on how a classic tractor with internal combustion engine can be modified so that it is powered by a battery-powered electric motor. The article presents equipment and components with which a tractor can be modified so that it can run on electricity. In general, an electric tractor consists of the chassis from which the heat engine, electric motor, battery, control and configuration equipment, software used and communication equipment, of the electronic systems on board the tractor are removed
ASPECTS REGARDING THE OBJECTIVES, PRINCIPLES AND NORMS OF ORGANIC AGRICULTURE
Organic farming can be defined as a production system that broadly avoids or excludes the use of synthetic compound fertilizers, pesticides, growth regulators and feed additives. Organic farming systems are based on crop rotation, the use of crop residues, animal manure or off-farm organic waste.This article presents the advantages and importance of this system of agriculture, by analyzing the objectives, principles and rules of organic farming, in the context of the high needs of the population to consume organic products
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