360 research outputs found
Recreation Strategies For The Retention Of First-Semester College Students
The high dropout rate of first-semester freshmen in a small, church-related college was addressed by the implementation of an organized recreation/activity strategy. This strategy was designed to provide appropriate entertainment and to contribute to a positive environment in order to integrate first-semester freshmen into the college environment and thereby increase retention. Evaluation instruments measured student--as well as faculty, staff, and administration--satisfaction with the campus environment and social/recreational activities. Moreover participation was monitored to assess the level of involvement. The writer concluded that the greater the level of participation in relevant organized activities emphasizing social integration, the greater the level of satisfaction of the campus environment by the target group, firs-semester freshmen, and the general student population. The system used to plan implement, and evaluate the program was discussed. Appendices include a questionnaire, survey examples and results, and samples of calendar and publicity posters
Ghost constraints and the covariant quantization of the superparticle in ten dimensions
We present a modification of the Berkovits superparticle. This is firstly in
order to covariantly quantize the pure spinor ghosts, and secondly to
covariantly calculate matrix elements of a generic operator between two states.
We proceed by lifting the pure spinor ghost constraints and regaining them
through a BRST cohomology. We are then able to perform a BRST quantization of
the system in the usual way, except for some interesting subtleties. Since the
pure spinor constraints are reducible, ghosts for ghosts terms are needed,
which have so far been calculated up to level 4. Even without a completion of
these terms, we are still able to calculate arbitrary matrix elements of a
physical operator between two physical states.Comment: 38 pages, Latex, no figures. Published versio
N=4 Superconformal Symmetry for the Covariant Quantum Superstring
We extend our formulation of the covariant quantum superstring as a WZNW
model with N=2 superconformal symmetry to N=4. The two anticommuting BRST
charges in the N=4 multiplet of charges are the usual BRST charge Q_S and a
charge Q_V proposed by Dijkgraaf, Verlinde and Verlinde for topological models.
Using our recent work on "gauging cosets", we then construct a further charge
Q_C which anticommutes with Q_S + Q_V and which is intended for the definition
of the physical spectrum.Comment: LaTeX, 18 pages, no figure
Overview of normal behavior modeling approaches for SCADA-based wind turbine condition monitoring demonstrated on data from operational wind farms
Condition monitoring and failure prediction for wind turbines currently comprise a hot research topic. This follows from the fact that investments in the wind energy sector have increased dramatically due to the transition to renewable energy production. This paper reviews and implements several techniques from state-of-the-art research on condition monitoring for wind turbines using SCADA data and the normal behavior modeling framework. The first part of the paper consists of an in-depth overview of the current state of the art. In the second part, several techniques from the overview are implemented and compared using data (SCADA and failure data) from five operational wind farms. To this end, six demonstration experiments are designed. The first five experiments test different techniques for the modeling of normal behavior. The sixth experiment compares several techniques that can be used for identifying anomalous patterns in the prediction error. The selection of the tested techniques is driven by requirements from industrial partners, e.g., a limited number of training data and low training and maintenance costs of the models. The paper concludes with several directions for future work.</p
Language intermediaries and local agency: peacebuilding, translation/interpreting and political disempowerment in 'mature' post-Dayton Bosnia-Herzegovina
The peace negotiations that ended the 1992–95 war in Bosnia-Herzegovina established a constitutional system of ethnic power-sharing that satisfied its signatories (the presidents of Serbia, Croatia and Bosnia) enough for war to cease and provided for international military and civilian peacebuilding to play a significant role in post-conflict Bosnia’s governance and economy. This indefinite peacebuilding mission, still ongoing in a downsized form, depended – like any other form of intervention where foreigners work across linguistic boundaries – on interlinguistic mediation by locally-recruited translators/interpreters, an aspect of knowledge production that even current peace and conflict research into peacebuilding’s micropolitics often neglects. On an individual level, locally-recruited interpreters’ frequently-overlooked agency was integral to peacebuilding practice. Yet theorising their agency must also acknowledge the macrosocial level, where the post-war constitutional system has often been argued to have stripped Bosnians of political agency, since it foreclosed political participation as anything but an ethnic subject corresponding to the three institutionalised ethnic identities (Bosniak, Croat or Serb). The entrenched and growing disconnect between political elites and the public, expressed through social protest in 2014, foregrounds the problem of agency and dis/empowerment in Bosnian society more sharply than research on the politics of translation/interpreting and peacebuilding in Bosnia before 2014 took into account, yet reveals further articulations of how international peacebuilding and domestic political contestation were intertwined
Vertex Operators for Closed Superstrings
We construct an iterative procedure to compute the vertex operators of the
closed superstring in the covariant formalism given a solution of IIA/IIB
supergravity. The manifest supersymmetry allows us to construct vertex
operators for any generic background in presence of Ramond-Ramond (RR) fields.
We extend the procedure to all massive states of open and closed superstrings
and we identify two new nilpotent charges which are used to impose the gauge
fixing on the physical states. We solve iteratively the equations of the vertex
for linear x-dependent RR field strengths. This vertex plays a role in studying
non-constant C-deformations of superspace. Finally, we construct an action for
the free massless sector of closed strings, and we propose a form for the
kinetic term for closed string field theory in the pure spinor formalism.Comment: TeX, harvmac, amssym.tex, 41 pp; references adde
Origin of Pure Spinor Superstring
The pure spinor formalism for the superstring, initiated by N. Berkovits, is
derived at the fully quantum level starting from a fundamental
reparametrization invariant and super-Poincare invariant worldsheet action. It
is a simple extension of the Green-Schwarz action with doubled spinor degrees
of freedom with a compensating local supersymmetry on top of the conventional
kappa-symmetry. Equivalence to the Green-Schwarz formalism is manifest from the
outset. The use of free fields in the pure spinor formalism is justified from
the first principle. The basic idea works also for the superparticle in 11
dimensions.Comment: 21 pages, no figure; v2: refs. adde
The Quantum Superstring as a WZNW Model with N=2 Superconformal Symmetry
We present a new development in our approach to the covariant quantization of
superstrings in 10 dimensions which is based on a gauged WZNW model. To
incorporate worldsheet diffeomorphisms we need the quartet of ghosts
(b_{zz},c^{z}, \b_{zz}, \g^{z}) for topological gravity. The currents of this
combined system form an N=2 superconformal algebra. The model has vanishing
central charge and contains two anticommuting BRST charges, Q_{S}=Q_{W} +
\oint \g^{z} b_{zz} + \oint \eta_{z} and Q_{V} = \oint c^{z} \Big(T^{W}_{zz}
+ {1\over 2} T^{top}_{zz}\Big) + \g^{z} (B^{W}_{zz} + {1\over 2} B^{top}_{zz}
\Big), where is obtained by the usual fermionization of \b_{zz},
\g^{z}. Physical states form the cohomology of , have nonnegative
grading, and are annihilated by and . We no longer introduce
any ghosts by hand, and the formalism is completely Lorentz covariant.Comment: 26 pages, harmvac; major additions and new result
Towards Pure Spinor Type Covariant Description of Supermembrane -- An Approach from the Double Spinor Formalism --
In a previous work, we have constructed a reparametrization invariant
worldsheet action from which one can derive the super-Poincare covariant pure
spinor formalism for the superstring at the fully quantum level. The main idea
was the doubling of the spinor degrees of freedom in the Green-Schwarz
formulation together with the introduction of a new compensating local
fermionic symmetry. In this paper, we extend this "double spinor" formalism to
the case of the supermembrane in 11 dimensions at the classical level. The
basic scheme works in parallel with the string case and we are able to
construct the closed algebra of first class constraints which governs the
entire dynamics of the system. A notable difference from the string case is
that this algebra is first order reducible and the associated BRST operator
must be constructed accordingly. The remaining problems which need to be solved
for the quantization will also be discussed.Comment: 40 pages, no figure, uses wick.sty; v2: a reference added, published
versio
Non-BPS D-Branes in Light-Cone Green-Schwarz Formalism
Non-BPS D-branes are difficult to describe covariantly in a manifestly
supersymmetric formalism. For definiteness we concentrate on type IIB string
theory in flat background in light-cone Green-Schwarz formalism. We study both
the boundary state and the boundary conformal field theory descriptions of
these D-branes with manifest SO(8) covariance and go through various
consistency checks. We analyze Sen's original construction of non-BPS D-branes
given in terms of an orbifold boundary conformal field theory. We also directly
study the relevant world-sheet theory by deriving the open string boundary
condition from the covariant boundary state. Both these methods give the same
open string spectrum which is consistent with the boundary state, as required
by the world-sheet duality. The boundary condition found in the second method
is given in terms of bi-local fields that are quadratic in Green-Schwarz
fermions. We design a special ``doubling trick'' suitable to handle such
boundary conditions and prescribe rules for computing all possible correlation
functions without boundary insertions. This prescription has been tested by
computing disk one-point functions of several classes of closed string states
and comparing the results with the boundary state computation.Comment: 47 pages, 1 figure. Typos corrected, references added and slight
modification of certain explanation made. Version accepted for publication in
JHE
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