2,066 research outputs found
Almost-Commutative Geometries Beyond the Standard Model II: New Colours
We will present an extension of the standard model of particle physics in its
almost-commutative formulation. This extension is guided by the minimal
approach to almost-commutative geometries employed in [13], although the model
presented here is not minimal itself.
The corresponding almost-commutative geometry leads to a Yang-Mills-Higgs
model which consists of the standard model and two new fermions of opposite
electro-magnetic charge which may possess a new colour like gauge group. As a
new phenomenon, grand unification is no longer required by the spectral action.Comment: Revised version for publication in J.Phys.A with corrected Higgs
masse
Almost-Commutative Geometries Beyond the Standard Model III: Vector Doublets
We will present a new extension of the standard model of particle physics in
its almostcommutative formulation. This extension has as its basis the algebra
of the standard model with four summands [11], and enlarges only the particle
content by an arbitrary number of generations of left-right symmetric doublets
which couple vectorially to the U(1)_YxSU(2)_w subgroup of the standard model.
As in the model presented in [8], which introduced particles with a new colour,
grand unification is no longer required by the spectral action. The new model
may also possess a candidate for dark matter in the hundred TeV mass range with
neutrino-like cross section
On Spectral Triples in Quantum Gravity II
A semifinite spectral triple for an algebra canonically associated to
canonical quantum gravity is constructed. The algebra is generated by based
loops in a triangulation and its barycentric subdivisions. The underlying space
can be seen as a gauge fixing of the unconstrained state space of Loop Quantum
Gravity. This paper is the second of two papers on the subject.Comment: 43 pages, 1 figur
New Lower Bounds on the Self-Avoiding-Walk Connective Constant
We give an elementary new method for obtaining rigorous lower bounds on the
connective constant for self-avoiding walks on the hypercubic lattice .
The method is based on loop erasure and restoration, and does not require exact
enumeration data. Our bounds are best for high , and in fact agree with the
first four terms of the expansion for the connective constant. The bounds
are the best to date for dimensions , but do not produce good results
in two dimensions. For , respectively, our lower bound is within
2.4\%, 0.43\%, 0.12\%, 0.044\% of the value estimated by series extrapolation.Comment: 35 pages, 388480 bytes Postscript, NYU-TH-93/02/0
The Standard Model with gravity couplings
In this paper, we examine the coupling of matter fields to gravity within the
framework of the Standard Model of particle physics. The coupling is described
in terms of Weyl fermions of a definite chirality, and employs only
(anti)self-dual or left-handed spin connection fields. It is known from the
work of Ashtekar and others that such fields can furnish a complete description
of gravity without matter. We show that conditions ensuring the cancellation of
perturbative chiral gauge anomalies are not disturbed. We also explore a global
anomaly associated with the theory, and argue that its removal requires that
the number of fundamental fermions in the theory must be multiples of 16. In
addition, we investigate the behavior of the theory under discrete
transformations P, C and T; and discuss possible violations of these discrete
symmetries, including CPT, in the presence of instantons and the
Adler-Bell-Jackiw anomaly.Comment: Extended, and replaced with LaTex file. 25 Page
Fermi-level alignment at metal-carbon nanotube interfaces: application to scanning tunneling spectroscopy
At any metal-carbon nanotube interface there is charge transfer and the
induced interfacial field determines the position of the carbon nanotube band
structure relative to the metal Fermi-level. In the case of a single-wall
carbon nanotube (SWNT) supported on a gold substrate, we show that the charge
transfers induce a local electrostatic potential perturbation which gives rise
to the observed Fermi-level shift in scanning tunneling spectroscopy (STS)
measurements. We also discuss the relevance of this study to recent experiments
on carbon nanotube transistors and argue that the Fermi-level alignment will be
different for carbon nanotube transistors with low resistance and high
resistance contacts.Comment: 4 pages, 3 ps figures, minor corrections, accepted by Phys. Rev. Let
Mutuality of Rogers's therapeutic conditions and treatment progress in the first three psychotherapy sessions
Abstract
Objective: Research on the effects of Rogers’s therapeutic relationship conditions has typically focused on the unilateral provision of empathy, unconditional positive regard, and congruence from therapist to client. Method: This study looked at both client and therapist mutuality of the Rogerian therapeutic conditions and the association between mutuality and treatment progress in the first three psychotherapy sessions. Clients (N = 62; mean age = 24.32; 77% female, 23% male) and therapists (N = 12; mean age = 34.32; nine female and three male) rated one another using the Barrett-Lennard Relationship Inventory after the first and third session. Results: Both clients and therapists perceived the quality of the
relationship as improved over time. Client rating of psychological distress (CORE-OM) was lower after session 3 than at session 1 (es = .85, [95% CIs: .67, 1.03]). Hierarchical multiple regression was used to test the predictive power of mutually high levels of the therapeutic conditions on treatment progress. The association between client rating of therapist-provided
conditions and treatment progress at session 3 was higher when both clients and therapists rated each other as providing high levels of the therapeutic conditions (R2 change = .073, p < .03). Conclusions: The findings suggest mutuality of Rogers’s therapeutic conditions is related to treatment progress.
Keywords: therapeutic relationship; psychotherapy; mutuality; treatment progres
The UK Environmental Change Network datasets – integrated and co-located data for long-term environmental research (1993–2015)
Long-term datasets of integrated environmental variables, co-located together, are relatively rare. The UK Environmental Change Network (ECN) was launched in 1992 and provides the UK with its only long-term integrated environmental monitoring and research network for the assessment of the causes and consequences of environmental change. Measurements, covering a wide range of physical, chemical, and biological “driver” and “response” variables are made in close proximity at ECN terrestrial sites using protocols incorporating standard quality control procedures. This paper describes the datasets (there are 19 published ECN datasets) for these co-located measurements, containing over 20 years of data (1993–2015). The data and supporting documentation are freely available from the NERC Environmental Information Data Centre under the terms of the Open Government Licence (see paper for DOIs)
The Reliability of Global and Hemispheric Surface Temperature Records
The purpose of this review article is to discuss the development and associated estimation of uncertainties in the global and hemispheric surface temperature records. The review begins by detailing the groups that produce surface temperature datasets. After discussing the reasons for similarities and differences between the various products, the main issues that must be addressed when deriving accurate estimates, particularly for hemispheric and global averages, are then considered. These issues are discussed in the order of their importance for temperature records at these spatial scales: biases in SST data, particularly before the 1940s; the exposure of land-based thermometers before the development of louvred screens in the late 19th century; and urbanization effects in some regions in recent decades. The homogeneity of land-based records is also discussed; however, at these large scales it is relatively unimportant. The article concludes by illustrating hemispheric and global temperature records from the four groups that produce series in near-real time
Research methods in Science Education in Latin America: how we researched in the 2000s
Neste trabalho apresentamos os resultados de uma pesquisa sobre as metodologias e instrumentos de pesquisa usados nos artigos publicados nas principais revistas da área de ensino de ciências da América Latina no período 2000-2009. A partir destes dados, discutimos diferentes aspectos que podem ser úteis para melhorar a qualidade da pesquisa na área
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