PARADOXICAL KINEMATIC ACAUSALITY IN WEINBERG’S EQUATIONS FOR MASSLESS PARTICLES OF ARBITRARY SPIN

1992 ◽  
Vol 07 (22) ◽  
pp. 1967-1974 ◽  
Author(s):  
D.V. AHLUWALIA ◽  
D.J. ERNST
Keyword(s):  
Wave Equations ◽  
Classical Group ◽  
Arbitrary Spin ◽  
The Other ◽  
Finite Mass ◽  
Massless Particles ◽  
Paradoxical Situation ◽  
Other Hand ◽  
Free Particles

Weinberg’s equations for massless free particles of arbitrary spin are found to have acausal solutions. On the other hand, the m→0 limit of Joos-Weinberg’s finite-mass wave equations satisfied by (j, 0)⊕(0, j) j) covariant spinors are free from all kinematic acausality. This paradoxical situation is resolved and corrected by carefully studying the transition from the classical group theoretical arguments to quantum mechanically interpreted equations.

Linear Stability of a Plasma Diode

1969 ◽  
Vol 24 (8) ◽  
pp. 1235-1243 ◽  
Author(s):  
M Dobrowolny ◽  
F Engelmann ◽  
A Sestero
Keyword(s):  
Boundary Conditions ◽  
Linear Stability ◽  
Plane Waves ◽  
The Other ◽  
Other Hand ◽  
Free Particles ◽  
Plasma Diode ◽  
The Stability

AbstractThe stability of a plasma diode with respect to longitudinal oscillations is investigated. If there are free particles emitted by the electrodes, the perturbations do not have the same dynamics as they would in an infinite plasma, contrary to the case where only particles trapped in the diode are present. This can be interpreted as due to a coupling of plane waves of different wave lengths, introduced by the boundary conditions at the electrodes. The occurrence of resonant-particle effects, on the other hand, is subjected to precisely the same conditions as in an infinite plasma.

scholarly journals A necessidade do impossível: o paradoxo da historiografia literária no Brasil nas primeiras décadas após a independência

Navegações ◽  
2018 ◽  
Vol 10 (2) ◽  
pp. 165
Author(s):  
Luís Roberto De Souza Júnior
Keyword(s):  
The Other ◽  
Symbolic System ◽  
Brazilian Literature ◽  
Literary Historiography ◽  
Paradoxical Situation ◽  
Other Hand ◽  
Definition Of ◽  
Literary System

A historiografia literária brasileira viveu uma situação paradoxal nas primeiras décadas após a Independência do país (1822). A literatura, na condição de item de um sistema simbólico que ajudava a delinear o conceito de nação, precisava de uma historiografia para legitimá-la. Por outro lado, não era possível cunhar uma historiografia, dado que o Brasil não possuía ainda obras representativas de um sistema literário, conforme os parâmetros estabelecidos por Antonio Candido. O artigo trata desse paradoxo, tomando como base em textos de estudiosos da literatura e historiadores. Também se mostra como essa situação transparece em três textos do período: “Sobre a história da literatura do Brasil” (1836), de Gonçalves de Magalhães; “Bosquejo da história da poesia brasileira” (1840/41), de Joaquim Norberto de Sousa Silva; e “Da nacionalidade da literatura brasileira” (1843), de Santiago Nunes Ribeiro.********************************************************************The need of the impossible: the paradox of Brazilian Literaturein the first decades after the country’s independenceAbstract: Brazilian literary historiography lived a paradoxical situation in the first decades after the country’s independence (1822). The literature, as a part of a symbolic system that helped to shape the concept of nation, needed a historiography to legitimize it. On the other hand, it was not possible to coin a historiography, given that Brazil did not yet have enough representative works that would constitute a literary system, according to the definition of Antonio Candido. Based on texts of literature scholars and historians, this article analyses this paradox. It also shows how this situation is seen in three texts of the period: “Sobre a história da literatura do Brasil” (1836), by Gonçalves de Magalhães; “Bosquejo da história da poesia brasileira” (1840/41), by Joaquim Norberto de Sousa Silva; and “Da nacionalidade da literatura brasileira” (1843), by Santiago Nunes Ribeiro.Keywords: Literary historiography; Brazilian literature; Literary system

CONFORMAL COUPLING'S OUTRAGEOUS LEGACY

2002 ◽  
Vol 11 (10) ◽  
pp. 1531-1536
Author(s):  
L. RAUL ABRAMO ◽  
LEON BRENIG ◽  
EDGARD GUNZIG
Keyword(s):  
Scalar Field ◽  
Scalar Curvature ◽  
The Other ◽  
Minimal Coupling ◽  
Quantum Stability ◽  
Paradoxical Situation ◽  
Other Hand ◽  
The One ◽  
Hilbert Action ◽  
Scalar Gravity

In Einstein's gravity, non-minimal coupling of a scalar field to the scalar curvature leads to a paradoxical situation. On the one hand, it opens the way to qualitatively new cosmological dynamics. On the other hand, there are sectors of non-minimally coupled scalar-gravity theories for which the Einstein–Hilbert action reverses its sign, which seems to indicate that the whole system is unstable. We show how conformal coupling bypasses this problem. Due to a subtle interplay between gravity and the scalar field, classical and quantum stability are guaranteed globally. This liberates conformal coupling from a serious obstacle. Inflationary solutions in the new sector are also presented, which are validated by current observations.

A wave equation for massive particles of arbitrary spin

1967 ◽  
Vol 297 (1450) ◽  
pp. 351-364 ◽  
Keyword(s):  
Wave Equation ◽  
Arbitrary Spin ◽  
Field Vector ◽  
Second Order ◽  
The Other ◽  
Particle Field ◽  
Gravitational Fields ◽  
Other Hand ◽  
Free Case ◽  
Unique Spin

A wave equation is given which, in the force-free case, describes a particle of unique spin and mass and which remains consistent when interactions are included. The equation is simple in the sense that it involves only matrices which satisfy the Pauli commutation rules. This simplicity is achieved at the expense of extending the particle field vector from one of 2j + 1 components to one of 4j. However, the extra 2j — 1 components are just what are needed to remove the inconsistency of the interacting system. In the force-free case these additional components vanish and the resulting equations are equivalent to the usual ones of Dirac, Fierz and Pauli. One the other hand, for the interacting system, the extra components do not vanish. The second order propagation equations are deduced in the case of external electromagnetic and gravitational fields.

scholarly journals Broadcast television flow scheduling and the viewers’ zapping: conflicting practices

2016 ◽  
Vol 10 (4) ◽  
Author(s):  
Eduardo Cintra Torres
Keyword(s):  
Older People ◽  
The Other ◽  
Cable Tv ◽  
Broadcast Television ◽  
Paradoxical Situation ◽  
Other Hand ◽  
Consecutive Period ◽  
The One

Broadcast television and its audiences live a paradoxical situation: on the one hand, channels still schedule according to the concept of flow; on the other hand, viewers’ zapping counters it. This paper wishes to ascertain the audiences’ practices regarding their fidelity to flow. The research tries to answer these questions: how many viewers watch the same channel during a long consecutive period? How many viewers watch a complete programme? Are there significant differences in zapping versus flow faithfulness according to sex, age, socio-demographic class and cable TV access? Is “companionship television” still a viewers’ consume practice? The research verifies the effectiveness of flow scheduling, which, while being an ideology and a scheduling and self-promotion practice, is not a practice of most viewers. The results show that flow faithfulness flow is a minority behaviour mainly of older people, women, lower classes and viewers without occupation.

Lagos Elite Women and the Struggle for Legitimacy

2017 ◽  
Author(s):  
Saheed Aderinto
Keyword(s):  
Women's Rights ◽  
Sexual Politics ◽  
The Other ◽  
Women’S Rights ◽  
Paradoxical Situation ◽  
Other Hand ◽  
The One ◽  
Illicit Sexuality ◽  
Prostitution Laws

This chapter focuses on Lagos elite women's sexual politics. Lagos elite women were the first to insert illicit sexuality into their long list of projects aimed at improving women's sociopolitical and economic visibility. Like the male nationalists, they expressed optimism that the 1940s prohibitionist regime would help curb the menace of prostitution, especially the trafficking of girls. With time, the elite women would be disappointed by the paradoxical situation resulting from anti-prostitution laws: on the one hand, they fulfilled the demand for policing prostitutes and controlling the influx of girls into Lagos, but on the other hand, they opened up new arenas for the violation of women's rights.

Developing Creative Thinking in Arithmetic

1957 ◽  
Vol 4 (1) ◽  
pp. 10-12
Author(s):  
Calvin H. Reed
Keyword(s):  
Creative Thinking ◽  
The Other ◽  
Creative Thought ◽  
Paradoxical Situation ◽  
Other Hand ◽  
The One

IN THIS DECADE OF 1950–60, we find ourselves faced with a paradoxical situation. On the one hand, we pay high tribute to the creative minds that have helped to make America great—politically, economically, scientifically, and socially. We bestow our admiration on our Einsteins, Carvers, Edisons, Salks, Jeffersons, and others, because they contributed much to make our lives richer and happier. These men were creative thinkers. On the other hand, as we review the contemporary scene, we can identify people, forces and institutions that are suppressing creative thought and opinions of individuals.

A study of cometary eruptions through OH radio-lines

1999 ◽  
Vol 173 ◽  
pp. 249-254
Author(s):  
A.M. Silva ◽  
R.D. Miró
Keyword(s):  
Short Duration ◽  
Growth Curves ◽  
The Other ◽  
Initial Mass ◽  
Radio Lines ◽  
Other Hand ◽  
Sudden Rise

AbstractWe have developed a model for theH2OandOHevolution in a comet outburst, assuming that together with the gas, a distribution of icy grains is ejected. With an initial mass of icy grains of 108kg released, theH2OandOHproductions are increased up to a factor two, and the growth curves change drastically in the first two days. The model is applied to eruptions detected in theOHradio monitorings and fits well with the slow variations in the flux. On the other hand, several events of short duration appear, consisting of a sudden rise ofOHflux, followed by a sudden decay on the second day. These apparent short bursts are frequently found as precursors of a more durable eruption. We suggest that both of them are part of a unique eruption, and that the sudden decay is due to collisions that de-excite theOHmaser, when it reaches the Cometopause region located at 1.35 × 105kmfrom the nucleus.

Closing the GAP—A 5Å Scanning Microscope

1969 ◽  
Vol 27 ◽  
pp. 6-7
Author(s):  
A. V. Crewe
Keyword(s):  
Normal Form ◽  
The Other ◽  
Resolving Power ◽  
Scanning Microscope ◽  
Conventional Microscope ◽  
Other Hand ◽  
Closing The Gap ◽  
Thermal Sources ◽  
Better Than ◽  
Transmission Microscope

We have become accustomed to differentiating between the scanning microscope and the conventional transmission microscope according to the resolving power which the two instruments offer. The conventional microscope is capable of a point resolution of a few angstroms and line resolutions of periodic objects of about 1Å. On the other hand, the scanning microscope, in its normal form, is not ordinarily capable of a point resolution better than 100Å. Upon examining reasons for the 100Å limitation, it becomes clear that this is based more on tradition than reason, and in particular, it is a condition imposed upon the microscope by adherence to thermal sources of electrons.

Life Beyond 1MeV

1980 ◽  
Vol 38 ◽  
pp. 30-33
Author(s):  
K.H. Westmacott
Keyword(s):  
Electron Microscopy ◽  
Past Experience ◽  
The Other ◽  
Good Case ◽  
Other Hand ◽  
The U.S

Life beyond 1MeV – like life after 40 – is not too different unless one takes advantage of past experience and is receptive to new opportunities. At first glance, the returns on performing electron microscopy at voltages greater than 1MeV diminish rather rapidly as the curves which describe the well-known advantages of HVEM often tend towards saturation. However, in a country with a significant HVEM capability, a good case can be made for investing in instruments with a range of maximum accelerating voltages. In this regard, the 1.5MeV KRATOS HVEM being installed in Berkeley will complement the other 650KeV, 1MeV, and 1.2MeV instruments currently operating in the U.S. One other consideration suggests that 1.5MeV is an optimum voltage machine – Its additional advantages may be purchased for not much more than a 1MeV instrument. On the other hand, the 3MeV HVEM's which seem to be operated at 2MeV maximum, are much more expensive.

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