Expected Supremum of a Random Linear Combination of Shifted Kernels

We address the expected supremum of a linear combination of shifts of the sinc kernel with random coefficients. When the coefficients are Gaussian, the expected supremum is of order \sqrt{\log n}, where n is the number of shifts. When the coefficients are uniformly bounded, the expected supremum is of order \log\log n. This is a noteworthy difference to orthonormal functions on the unit interval, where the expected supremum is of order \sqrt{n\log n} for all reasonable coefficient statistics.Comment: To appear in the Journal of Fourier Analysis and Application

Polishing The Mirror: A Multiple Methods Study Of The Relationship Between Teaching Style And The Application Of Technology In Alaska's Rural One To One Digital Classrooms

Thesis (Ph.D.) University of Alaska Fairbanks, 2012This mixed method survey study examined the inter-relationships between teaching styles and the depth of classroom-based technology applications used by teachers participating in 1:1 digitally enhanced classrooms in thirteen of Alaska's rural school districts. The promise of technology to catalyze the transformation of schools into learner centric environments preparing students to be 21st century learners has not been realized. Significant first order barriers have limited the digital learning resources necessary to systemically affect pedagogical change. During the last six years, various entities have sponsored digitally enhanced learning environments to stimulate the process of education reform. These initiatives, labeled as one-to-one (1:1), brought teachers face-to-face with the challenges related to second order education reform while creating an opportunity to study changes in instructional philosophy and practice as a result of teaching in an environment rich in technology. This study explored three questions formulated to probe the relationship between pedagogical philosophy and the application of 1:1 technology to support learning: • "What is the relationship between instructional philosophy and the way teachers use technology to support learning in Alaskan high school 1:1 laptop programs?" • "How does access to a 1:1 classroom affect a teacher's instructional philosophy or practice?" • "Does access to a 1:1 digitally enhanced teaching environment facilitate the use of instructional practices consistent with Alaska Native and 21st century learner outcomes?" Ninety-four rural high school teachers responded to a survey that assessed teaching styles on a continuum from transmission to constructivist. The level of technology adoption was examined using three indices that respectively measure the professional, personal and classroom use of technology by teachers. Information derived from open ended questions was triangulated with quantitative data to develop a meaningful understanding of the study questions. Quantitative and qualitative data suggested that the majority of responding teachers identified with constructivist beliefs over traditional transmission. Teachers noted a strong positive relationship between teaching and the application of technology, yet analysis showed that constructivist beliefs were attenuated by several challenges related to management of technology. While teachers were generally aware of the potential for digital learning technologies to support Alaska Native and 21st century methods, they were outweighed by operational concerns related to the integration of technology. These study questions are significant. Digitally enhanced instructional practices help to equip students with the skills expected of 21st century learners. Perhaps even more significant is the congruence between the teaching styles traditionally used by Alaska Natives and the digitally enhanced constructivist practices made possible when using technology to augment processes for acquiring knowledge

Molecular Hydrogen in a Damped Lyman-alpha System at z_abs=4.224

We present the direct detection of molecular hydrogen at the highest redshift known today (z_abs=4.224) in a Damped Lyman-alpha (DLA) system toward the quasar PSS J1443+2724. This absorber is remarkable for having one of the highest metallicities amongst DLA systems at z_abs>3, with a measured iron abundance relative to Solar of -1.12+/-0.10. We provide for the first time in this system accurate measurements of NI, MgII, SII and ArI column densities. The sulfur and nitrogen abundances relative to Solar, -0.63+/-0.10 and -1.38+/-0.10 respectively, correspond exactly to the primary nitrogen production plateau. H2 absorption lines are detected in four different rotational levels (J=0, 1, 2 and 3) of the vibrational ground-state in three velocity components with total column densities of log N(H2)=17.67, 17.97, 17.48 and 17.26 respectively. The J=4 level is tentatively detected in the strongest component with log N(H2)~14. The mean molecular fraction is log f=-2.38+/-0.13, with f=2N(H2)/(2N(H2)+N(HI)). We also measure log N(HD)/N(H2)<-4.2. The excitation temperatures T_{01} for the two main components of the system are 96 and 136 K respectively. We argue that the absorbing galaxy, whose star-formation activity must have started at least 2-5x10^8 yrs before z=4.224, is in a quiescent state at the time of observation. The density of the gas is small, n_H<=50 cm^{-3}, and the temperature is of the order of T~90-180 K. The high excitation of neutral carbon in one of the components can be explained if the temperature of the Cosmic Microwave Background Radiation has the value expected at the absorber redshift, T=14.2 K.Comment: 13 pages, 3 figures, accepted for publication in ApJ Letter

The Polarized Spectrum of Apm 08279+5255

We report the discovery of significant linear polarization (p > 1%) in the hyperluminous z=3.87 BALQSO APM~08279+5255. The polarization spectrum is complex, with properties similar to those of other, lower redshift but more highly polarized BALQSOs. The resonance emission lines are unpolarized while the absorption troughs show polarization similar to or higher than the continuum. In particular, an apparent increase of polarization in the trough covering 1000-1030 angstroms (rest) supports the interpretation of this feature as a broad absorption component associated with OVI/Ly_beta local to the QSO, as opposed to an intervening damped Ly_alpha absorption system. The elevated polarization in some of the absorption features implies that we view the scattered (polarized) spectrum through a sightline with less absorbing material than the direct spectrum. Therefore, the complex structure of the polarization spectrum in this brilliant lensed BALQSO suggests that it will be an important laboratory for studying the structure of QSOs at high redshift.Comment: 8 pages, 1 figure. Accepted for publication in The Astrophysical Journal Letter

Blepharospasm plus Cervical Dystonia with Predominant Anterocollis: A Distinctive Subphenotype of Segmental Craniocervical Dystonia?

Background: Dystonia of the eyelids often spreads to affect other muscles in the craniocervical region. Certain blepharospasm-plus subphenotypes may be clinically unique. Methods: Seven subjects with the subphenotype of late-onset blepharospasm with apraxia of eyelid opening and cervical dystonia with predominant anterocollis were identified from a database of over 1800 patients with primary dystonia. Results: Blepharospasm was the first affected site in 6/7 subjects, followed by spread of the disease to the cervical muscles. Although four patients also had other forms of dystonia (laryngeal, lower face), none showed spread outside the craniocervical region. A family history of dystonia was present in 4/7. No mutations were identified in THAP1 or TOR1A. Overall, blepharospasm was difficult to treat, typically requiring both myectomy and substantial doses of botulinum toxin into the pretarsal orbicularis oculi muscles. In one subject, anterocollis markedly improved after deep brain stimulation. Discussion: Delineation and characterization of craniocervical dystonia subphenotypes may serve to guide genetic and therapeutic studies, in addition to clinical interventions. The blepharospasm with apraxia of eyelid opening and anterocollis subphenotype can be therapeutically challenging

Optimization of a Classical Stamping Progression by Modal Correction of Anisotropy Ears

This work is a development from the Inetforsmep European project. We proposed to realize a global optimization of a deep drawing industrial progression (made of several stages) for a cup manufacture. The objectives of the process were the thickness decrease and the geometrical parameters (especially the height). This paper improves on this previous work in the aim of mastering the contour error. From the optimal configuration, we expect to cut down the amount of the needed material and the number of forming operations. Our action is focused on the appearance of unexpected undulations (ears) located on the rim of the cups during forming due to a nonuniform crystallographic texture. Those undulations can cause a significant amount of scraps, productivity loss, and cost during manufacture. In this paper, this phenomenon causes the use of four forming operations for the cup manufacture. The aim is to cut down from four to two forming stages by defining an optimal blank (size and shape). The advantage is to reduce the cost of the tool manufacturing and to minimize the needed material (by suppressing the part flange). The chosen approach consists in defining a particular description of the ears' part by modal decomposition and then simulating several blank shapes and sizes generated by discrete cosine transformation (DCT). The use of a numerical simulation for the forming operation and the design of an experiment technique allow mathematical links between the ears' formation and the DCT coefficients. An optimization is then possible by using mathematical links. This original approach leads the ears' amplitude to be reduced by a factor of 10, with only 15 numerical experiments. Moreover, we have limited the number of forming stages from 4 to 2 with a minimal material use

Instability to a heterogeneous oscillatory state in randomly connected recurrent networks with delayed interactions

Oscillatory dynamics are ubiquitous in biological networks. Possible sources of oscillations are well understood in low-dimensional systems but have not been fully explored in high-dimensional networks. Here we study large networks consisting of randomly coupled rate units. We identify a type of bifurcation in which a continuous part of the eigenvalue spectrum of the linear stability matrix crosses the instability line at nonzero frequency. This bifurcation occurs when the interactions are delayed and partially antisymmetric and leads to a heterogeneous oscillatory state in which oscillations are apparent in the activity of individual units but not on the population-average level

Intervening Metal Systems in GRB and QSO sight-lines: The Mgii and Civ Question

Prochter et al. 2006 recently found that the number density of strong intervening 0.5<z<2 MgII absorbers detected in gamma-ray burst (GRB) afterglow spectra is nearly 4 times larger than in QSO spectra. We have conducted a similar study using CIV absorbers. Our CIV sample, consisting of a total of 20 systems, is drawn from 3 high resolution and high to moderate S/N VLT/UVES spectra of 3 long-duration GRB afterglows, covering the redshift interval 1.6< z<3.1. The column density distribution and number density of this sample do not show any statistical difference with the same quantities measured in QSO spectra. We discuss several possibilities for the discrepancy between CIV and MgII absorbers and conclude that a higher dust extinction in the MgII QSO samples studied up to now would give the most straightforward solution. However, this effect is only important for the strong MgII absorbers. Regardless of the reasons for this discrepancy, this result confirms once more that GRBs can be used to detect a side of the universe that was unknown before, not necessarily connected with GRBs themselves, providing an alternative and fundamental investigative tool of the cosmic evolution of the universe.Comment: 21 pages, 4 figures, ApJ accepted, Revised after Referee Repor

The Meinunger "Nicht Rote" Objects

Four high-latitude slow variable stars have been noted by Meinunger (1972) as "nicht rote" ("not red") objects and thus curious. We have previously reported (Margon & Deutsch 1997) that one of these objects, CC Boo, is in fact a QSO. Here we present observations demonstrating that the remaining three are also highly variable active galactic nuclei. The most interesting object of the four is perhaps S 10765 (= NGP9 F324-0276706), which proves to be a resolved galaxy at z=0.063. Despite the rapid and large reported variability amplitude (~1.6 mag), the spectrum is that of a perfectly normal galaxy, with no emission lines or evident nonthermal continuum. We also present new spectroscopic and photometric observations for AR CVn, suggested by Meinunger to be an RR Lyrae star despite its very faint magnitude (=19.4). The object is indeed one of the most distant RR Lyrae stars known, at a galactocentric distance of ~40 kpc.Comment: Accepted for publication in Publications of the Astronomical Society of the Pacific, Volume 111, January 1999; 14 pages including 4 figures and 1 tabl

A translucent interstellar cloud at z=2.69: CO, H2 and HD in the line-of-sight to SDSS J123714.60+064759.5

We present the analysis of a sub-DLA system (log N(H^0)=20.0+/-0.15, z_abs=2.69) toward SDSS J123714+064759 (z_em=2.78). Using the VLT/UVES and X-shooter spectrographs, we detect H2, HD and CO molecules in absorption with log N(H2,HD,CO)=(19.21,14.48,14.17). The overall metallicity of the system is super-solar ([Zn/H]=+0.34) and iron is highly depleted ([Fe/Zn]=-1.39), revealing metal-rich and dusty gas. The strongest H2 component does not coincide with the centre of the HI absorption. This implies that the molecular fraction in this component, f=2N(H2)/(2N(H2)+N(H^0)), is larger than the mean molecular fraction =1/4 in the system. This is supported by the detection of Cl^0 associated with this H2-component having N(Cl^0)/N(Cl^+)>0.4. Since Cl^0 is tied up to H2 by charge exchange reactions, this means that the molecular fraction in this component is not far from unity. The size of the molecular cloud is probably smaller than 1pc. Both the CO/H2=10^-5 and CO/C^0~1 ratios for f>0.24 indicate that the cloud classifies as translucent, i.e., a regime where carbon is found both in atomic and molecular form. The corresponding extinction, Av=0.14, albeit lower than the definition of a translucent sightline (based on extinction properties), is high for the observed H^0 column density. This means that intervening clouds with similar local properties but with larger column densities could be missed by current magnitude-limited QSO surveys. The excitation of CO is dominated by radiative interaction with the Cosmic Microwave Background Radiation (CMBR) and we derive Tex(CO)=10.5+0.8-0.6 K when TCMBR(z=2.69)=10.05 K is expected. The astration factor of deuterium -with respect to the primordial D/H ratio- is only about 3. This can be the consequence of accretion of unprocessed gas from the intergalactic medium onto the associated galaxy. [abridged]Comment: 17 pages, 21 figures, 8 tables, accepted for publication in A&