Electro-Optical Nanotraps for Neutral Atoms

We propose a new class of nanoscale electro-optical traps for neutral atoms. A prototype is the toroidal trap created by a suspended, charged carbon nanotube decorated with a silver nanosphere dimer. An illuminating laser field, blue detuned from an atomic resonance frequency, is strongly focused by plasmons induced in the dimer and generates both a repulsive potential barrier near the nanostructure surface and a large viscous damping force that facilitates trap loading. Atoms with velocities of several meters per second may be loaded directly into the trap via spontaneous emission of just two photons.Comment: 5 pages, 3 figures. Fig. 1 appeared on the cover of the January 23, 2009 issue of PR

Diffuse Interstellar Bands in z < 0.6 CaII Absorbers

The diffuse interstellar bands (DIBs) probably arise from complex organic molecules whose strength in local galaxies correlates with neutral hydrogen column density, N(HI), and dust reddening, E(B-V). Since CaII absorbers in quasar (QSO) spectra are posited to have high N(HI) and significant E(B-V), they represent promising sites for the detection of DIBs at cosmological distances. Here we present the results from the first search for DIBs in 9 CaII-selected absorbers at 0.07 < z_abs < 0.55. We detect the 5780Ang DIB in one line of sight at z_abs = 0.1556; this is only the second QSO absorber in which a DIB has been detected. Unlike the majority of local DIB sight-lines, both QSO absorbers with detected DIBs show weak 6284Ang absorption compared with the 5780Ang band. This may be indicative of different physical conditions in intermediate redshift QSO absorbers compared with local galaxies. Assuming that local relations between the 5780Ang DIB strength and N(HI) and E(B-V) apply in QSO absorbers, DIB detections and limits can be used to derive N(HI) and E(B-V). For the one absorber in this study with a detected DIB, we derive E(B-V) = 0.23mag and log[N(HI)] >= 20.9, consistent with previous conclusions that CaII systems have high HI column densities and significant reddening. For the remaining 8 CaII-selected absorbers with 5780Ang DIB non-detections, we derive E(B-V) upper limits of 0.1-0.3mag.Comment: 5 pages, 2 figures. Accepted to MNRAS Letter

Learning from Learning Groups

Collaborative learning is a key, and complementary, component of student-centred enquiry-based pedagogy. Today, many educators understand that students learn effectively when working together with their peers to construct new knowledge. Many teachers are working to help their students develop such ability. Teachers do this to help students better understand the relevance of new content, connect new ideas into existing frameworks of understanding, and construct new neurological pathways and connect synapses in their brains. In addition, group learning has been shown to increase students’ critical thinking skills, creativity, collaborative behaviours, understanding of ethics, and the like. In the literature, attention has been paid to how groups of students can most effectively work together. Even greater attention has been paid to how teams work in business and industry. On the other hand, relatively little research has been reported about how groups of faculty can enhance their own knowledge and performance by embracing the concept of group learning—by learning in groups themselves. At Dublin Institute of Technology (DIT) group learning is becoming the norm among teachers as well as students. As a result, DIT provides an ideal place to study the dynamics of group learning among teachers as well as among students. Moreover, in this particular institution, it is also possible to assess learning that occurs across groups—learning that filters its way up from the classroom into programmes, colleges, and administrative decision-making. This paper summarizes formal research into three aspects of the group-learning movement that has emerged at DIT. The overall project involves data collection and analysis of: (1) a faculty peer-learning group that facilitated (2) student peer-learning groups in classes across the electrical engineering curriculum as part of (3) a broad institutional program designed to support professional development and enhance learning and teaching. The project summarized here uses interpretive, qualitative methods to investigate the dynamics of group learning

Impairment of the CD8+ T cell response in lungs following infection with human respiratory syncytial virus is specific to the anatomical site rather than the virus, antigen, or route of infection

<p>Abstract</p> <p>Background</p> <p>A subset of the virus-specific CD8+ cytotoxic T lymphocytes (CTL) isolated from the lungs of mice infected with human respiratory syncytial virus (RSV) is impaired in the ability to secrete interferon γ (IFNγ), a measure of functionality. It was suggested that the impairment specifically suppressed the host cellular immune response, a finding that could help explain the ability of RSV to re-infect throughout life.</p> <p>Results</p> <p>To determine whether this effect is dependent on the virus, the route of infection, or the type of infection (respiratory, disseminated, or localized dermal), we compared the CTL responses in mice following intranasal (IN) infection with RSV or influenza virus or IN or intradermal (ID) infection with vaccinia virus expressing an RSV CTL antigen. The impairment was observed in the lungs after IN infection with RSV, influenza or vaccinia virus, and after a localized ID infection with vaccinia virus. In contrast, we observed a much higher percentage of IFNγ secreting CD8+ lymphocytes in the spleens of infected mice in every case.</p> <p>Conclusion</p> <p>The decreased functionality of CD8+ CTL is specific to the lungs and is not dependent on the specific virus, viral antigen, or route of infection.</p

Long-Term Adult Population Fluctuations and Distribution of the Spot, Leiostomus xanthurus, in Mississippi

Adult specimens of the spot, Leiostomus xanthurus, were collected from bayou, Mississippi Sound, and barrier island locations along the Gulf Coast of Mississippi from November 1982 to July 1989. The mean total length of all spot sampled in comparable gill net sets was 219 mm (± 14 standard deviation, n=4,338). Ninety-five percent of the spot were collected in the island and sound areas, where the salinity was higher than in the bayous. Catch per unit effort was high at island and sound stations in spring and autumn, with relatively few fish caught during the winter spawning season and summer. The relatively high frequency of spot observed at the island stations in the autumn was probably influenced by spawning migrations, and the high spring values may repesent a combination of two abundant year classes. The two greatest yearly collections, in 1983 and 1986, may have been influenced by sampling conditions or by environmental conditions favorable to survival either during those years or earlier when those fish were postlarvae. The smallest yearly catch occurred in 1985 and may have reflected the harsh weather conditions that year

Long-Term Adult Population Fluctuations and Distribution of the Spot, Leiostomus xanthurus, in Mississippi

Adult specimens of the spot, Leiostomus xanthurus, were collected from bayou, Mississippi Sound, and barrier island locations along the Gulf Coast of Mississippi from November 1982 to July 1989. The mean total length of all spot sampled in comparable gill net sets was 219 mm (± 14 standard deviation, n=4,338). Ninety-five percent of the spot were collected in the island and sound areas, where the salinity was higher than in the bayous. Catch per unit effort was high at island and sound stations in spring and autumn, with relatively few fish caught during the winter spawning season and summer. The relatively high frequency of spot observed at the island stations in the autumn was probably influenced by spawning migrations, and the high spring values may repesent a combination of two abundant year classes. The two greatest yearly collections, in 1983 and 1986, may have been influenced by sampling conditions or by environmental conditions favorable to survival either during those years or earlier when those fish were postlarvae. The smallest yearly catch occurred in 1985 and may have reflected the harsh weather conditions that year

Elliptical-core two mode fiber sensors and devices incorporating photoinduced refractive index gratings

Results of experiments performed using germanium-doped, elliptical core, two-mode optical fibers whose sensitivity to strain was spatially varied through the use of chirped, refractive-index gratings permanently induced into the core using Argon-ion laser light are presented. This type of distributed sensor falls into the class of eighted-fiber sensors which, through a variety of means, weight the strain sensitivity of a fiber according to a specified spatial profile. We describe results of a weighted-fiber vibration mode filter which successfully enhances the particular vibration mode whose spatial profile corresponds to the profile of the grating chirp. We report on the high temperature survivability of such grating-based sensors and discuss the possibility of multiplexing more than one sensor within a single fiber

An Improved Method For Calculating Critical Speeds And Rotordynamic Stability Of Turbomachinery

PaperPg. 141-145.A number of the computer programs for rotordynamic stability and critical speed prediction in common use during recent years have been based on the works of Myklestad, Prohl and Lund. Programs of this type, called transfer matrix programs, employ complex variables when damping or crosscoupling is included in the model. Most use an iteration scheme which at times fails to converge with sufficient accuracy on some critical speeds, and has been known to completely miss critical speeds on occasion. It is shown in this paper that by rearranging the calculations performed in a transfer matrix program one can derive the characteristic polynomial for a complex rotor-bearing system, with no loss in generality. The modeling procedures are identical for the rotor and bearing/ foundations, including the effects of gyroscopics, damping, and any or all destabilizing influences which are linearized in the usual manner. With the characteristic polynomial known, critical speeds can be estimated and stability predicted with greater efficiency and with no fear of missing any modes. Such a program has been written, and a complete comparison between the two types of programs is shown