Nonsingular Black Holes and Degrees of Freedom in Quantum Gravity

Spherically symmetric space-times provide many examples for interesting black hole solutions, which classically are all singular. Following a general program, space-like singularities in spherically symmetric quantum geometry, as well as other inhomogeneous models, are shown to be absent. Moreover, one sees how the classical reduction from infinitely many kinematical degrees of freedom to only one physical one, the mass, can arise, where aspects of quantum cosmology such as the problem of initial conditions play a role.Comment: 4 page

Selecting Features Of A Web Platform To Enhance Course Delivery

This paper reviews key features of popular Web platforms used for course delivery.  Institutions of higher education have rushed to adopt these platforms for several reasons. From the point of view of the educator, the most important reason is to enhance the classroom experience (real or virtual).  “Classroom” experiences can benefit from a continuous stream of discourse made possible by the communications tools available in the web platforms designed for educational application.  In addition, web platforms can serve as a means of collecting and distributing content from various sources – including all class participants.   A review of studies from current business education literature conducted to assess the pedagogical impact of the use of some of these features is included. The authors’ also provide excerpts from their pages and classroom experiences in a traditional classroom and in distance learning with asynchronous communication, including email and bulletin boards, synchronous communication, content creation that includes course outlines and handouts, online surveys and exams and the digital dropbox. Platforms which are reviewed include Blackboard v. 5.5, WebCT v. 3.0 and WebBoard v. 4.0

Unusual Shubnikov-de Haas oscillations in BiTeCl

We report measurements of Shubnikov-de Haas (SdH) oscillations in single crystals of BiTeCl at magnetic fields up to 31 T and at temperatures as low as 0.4 K. Two oscillation frequencies were resolved at the lowest temperatures, $F_{1}=65 \pm 4$ Tesla and $F_{2}=156 \pm 5$ Tesla. We also measured the infrared optical reflectance $\left(\cal R(\omega)\right)$ and Hall effect; we propose that the two frequencies correspond respectively to the inner and outer Fermi sheets of the Rashba spin-split bulk conduction band. The bulk carrier concentration was $n_{e}\approx1\times10^{19}$ cm$^{-3}$ and the effective masses $m_{1}^{*}=0.20 m_{0}$ for the inner and $m_{2}^{*}=0.27 m_{0}$ for the outer sheet. Surprisingly, despite its low effective mass, we found that the amplitude of $F_{2}$ is very rapidly suppressed with increasing temperature, being almost undetectable above $T\approx4$ K

Report Card On E-Mail: An Investigation Of Replies To Consumers

Organizational communications have been studied from several vantage points, and typically as a one-way communication tool.  Today, with the burgeoning growth and adoption of new technologies two-way communications have become ever more common.  While this paper focuses its research attention to specific forms of e-mail communications between organizations and those it seeks as consumers, a conceptual framework is also presented that sets a foundation for examining and evaluating the myriad of communications alternatives that are available to organizations and the publics they serve.   In this exploratory study 165 companies were e-mailed each of two messages and their responses to these e-mails were analyzed.  Firms used in the study were selected from seven different industries.  The findings reveal that many firms have serious problems responding to fairly simple and common communications.  Barely 45% of the firms studied responded to both types of inquiries, and many simply failed to respond.  Further, there was considerable variability in the timeliness, clarity and specificity of response.   While one may assume that e-mail communication, as a technology is well understood given its proliferation, there are several factors that are discussed that may impede responsiveness – in timeliness, clarity or specificity.  As a written form of communication, e-mail presents a challenge common to other forms of written communiqués; they provide a record that can be reviewed subsequent to the exchange between parties involved in communication.  As such, organizations may be reluctant to answer all e-mails for a myriad of reasons:  some may believe that e-mails place unnecessary or imposing demands on its workforce; some may fear that those responsible for handling the correspondence may be challenged to convey accurate, personalized information in an articulate manner; others simply do not want to have the burden of having to keep a record of such correspondence; yet others may simply view e-mail as a trivial or unimportant, irrespective of whether the communication was marked “urgent” or “confidential” by the sender; and others may fear that their e-mail correspondence is apt to become public, even if marked confidential – as email lacks the advantage of privacy that accompanied other more conventional written messages.  Finally, hypotheses for future research based on the Customer Response System model are presented

Bulk Fermi surface and electronic properties of Cu0.07_{0.07}Bi2_{2}Se3_{3}

The electronic properties of Cu$_{0.07}$Bi$_{2}$Se$_{3}$ have been investigated using Shubnikov-de Haas and optical reflectance measurements. Quantum oscillations reveal a bulk, three-dimensional Fermi surface with anisotropy $k^{c}_{F}/k^{ab}_{F}\approx$ 2 and a modest increase in free-carrier concentration and in scattering rate with respect to the undoped Bi$_{2}$Se$_{3}$, also confirmed by reflectivity data. The effective mass is almost identical to that of Bi$_{2}$Se$_{3}$. Optical conductivity reveals a strong enhancement of the bound impurity bands with Cu addition, suggesting that a significant number of Cu atoms enter the interstitial sites between Bi and Se layers or may even substitute for Bi. This conclusion is also supported by X-ray diffraction measurements, where a significant increase of microstrain was found in Cu$_{0.07}$Bi$_{2}$Se$_{3}$, compared to Bi$_{2}$Se$_{3}$.Comment: Accepted to Phys. Rev B (R

Time-reversal symmetry breaking versus superstructure

One of the mysteries of modern condenced-matter physics is the nature of the pseudogap state of the superconducting cuprates. Kaminski et al.1 claimed to have observed signatures of time-reversal symmetry breaking in the pseudogap regime in underdoped Bi2Sr2CaCu2O8+d (Bi2212). Here we argue that the observed dichroism is due to the 5x1 superstructure replica of the electronic bands and therefore cannot be considered as evidence for the spontaneous time-reversal symmetry breaking in cuprates.Comment: 5 pages, pd

Evolution of helicity in NOAA 10923 over three consecutive solar rotations

We have studied the evolution of magnetic helicity and chirality in an active region over three consecutive solar rotations. The region when it first appeared was named NOAA10923 and in subsequent rotations it was numbered NOAA 10930, 10935 and 10941. We compare the chirality of these regions at photospheric, chromospheric and coronal heights. The observations used for photospheric and chromospheric heights are taken from Solar Vector Magnetograph (SVM) and H_alpha imaging telescope of Udaipur Solar Observatory (USO), respectively. We discuss the chirality of the sunspots and associated H_alpha filaments in these regions. We find that the twistedness of superpenumbral filaments is maintained in the photospheric transverse field vectors also. We also compare the chirality at photospheric and chromospheric heights with the chirality of the associated coronal loops, as observed from the HINODE X-Ray Telescope.Comment: 8 pages, 4 figure