2,625 research outputs found
Detection and classification of supernovae beyond z~2 redshift with the James Webb Space Telescope
Future time-domain surveys for transient events in the near- and mid-infrared
bands will significantly extend our understanding about the physics of the
early Universe. In this paper we study the implications of a deep (~27 mag),
long-term (~3 years), observationally inexpensive survey with the James Webb
Space Telescope (JWST) within its Continuous Viewing Zone, aimed at discovering
luminous supernovae beyond z~2 redshift. We explore the possibilities for
detecting Superluminous Supernovae (SLSNe) as well as Type Ia supernovae at
such high redshifts and estimate their expected numbers within a relatively
small (~0.1 deg^2) survey area. It is found that we can expect ~10 new SLSNe
and ~50 SNe Ia discovered in the 1 < z < 4 redshift range. We show that it is
possible to get relatively accurate (sigma_z < 0.25) photometric redshifts for
Type Ia SNe by fitting their Spectral Energy Distributions (SED), redshifted
into the observed near-IR bands, with SN templates. We propose that Type Ia SNe
occupy a relatively narrow range on the JWST F220W-F440W vs F150W-F356W
color-color diagram between +/- 7 rest-frame days around maximum light, which
could be a useful classification tool for such type of transients. We also
study the possibility of extending the Hubble-diagram of Type Ia SNe beyond
redshift 2 up to z~4. Such high-z SNe Ia may provide new observational
constraints for their progenitor scenario.Comment: accepted for publication in Ap
Distance estimate and progenitor characteristics of SN 2005cs in M51
Distance to the Whirlpool Galaxy (M51, NGC 5194) is estimated using published
photometry and spectroscopy of the Type II-P supernova SN 2005cs. Both the
Expanding Photosphere Method (EPM) and the Standard Candle Method (SCM),
suitable for SNe II-P, were applied. The average distance (7.1 \pm 1.2 Mpc) is
in good agreement with earlier SBF- and PNLF-based distances, but slightly
longer than the distance obtained by Baron et al. for SN 1994I via the Spectral
Fitting Expanding Atmosphere Method (SEAM). Since SN 2005cs exhibited low
expansion velocity during the plateau phase, similarly to SN 1999br, the
constants of SCM were re-calibrated including the data of SN 2005cs as well.
The new relation is better constrained in the low velocity regime (v_{ph}(50) ~
1500 - 2000$ km/s), that may result in better distance estimates for such SNe.
The physical parameters of SN 2005cs and its progenitor are re-evaluated based
on the updated distance. All the available data support the low-mass (~ 9
M_\odot) progenitor scenario proposed previously by its direct detection with
the Hubble Space Telescope.Comment: 7 pages, 4 figures, 4 tables, accepted in MNRA
A photometric and spectroscopic study of the brightest northern Cepheids. III. A high-resolution view of Cepheid atmospheres
We present new high-resolution (R=40000) spectroscopic observations of 18
bright northern Cepheids carried out at David Dunlap Observatory, in 1997. The
measurements mainly extend those of presented in Paper I adding three more
stars (AW Per, SV Vul, T Mon). The spectra were obtained in the interval of
5900 A and 6660 A. New radial velocities determined with the cross-correlation
technique and the bisector technique are presented. We found systematic
differences between the spectroscopic and CORAVEL-type measurements as large as
1-3 km/s in certain phases. We performed Baade-Wesselink analysis for CK Cam
discovered by the Hipparcos satellite. The resulting radius is 31+/-1 Ro, which
is in very good agreement with recent period-radius relation by Gieren et al.
(1999). Observational pieces of evidence of possible velocity gradient
affecting the individual line profiles are studied. The FWHM of the metallic
lines, similarly to the velocity differences, shows a very characteristic phase
dependence, illustrating the effect of global compression in the atmosphere.
The smallest line widths always occur around the maximal radius, while the
largest FWHM is associated with the velocity reversal before the minimal
radius. Three first overtone pulsators do not follow the general trend: the
largest FWHM in SU Cas and SZ Tau occurs after the smallest radius, during the
expansion, while in V1334 Cyg there are only barely visible FWHM-variations.
The possibility of a bright yellow companion of V1334 Cyg is briefly discussed.
The observed line profile asymmetries can be partly associated with the
velocity gradient, which is also supported by the differences between
individual line velocities of different excitation potentials.Comment: 13 pages, 9 figures, accepted for publication in MNRA
Internal Marketing and Schools: The Slovenian Case Study
Schools in Slovenia are expected to address and respond to the changing environment. Breaking through the rigidity of traditions is a complex process. Internal marketing can be used for doing this. It is a process that focuses on teachers and students in order to increase effectiveness and efficiency of schools and also the level of satisfaction of ‘school customers’. The purpose of this paper is to discuss the elements of internal marketing which are essential for teacher and customer satisfaction and to indicate opportunities for the implementation of internal marketing philosophy and related strategies in Slovenian schools. The paper provides a theoretical framework, an analysis of the Slovenian legal framework and the results of the case study conducted in a grammar school. Data were collected through a group interview, a questionnaire and individual in-depth interviews. The findings show that although the concept of internal marketing is unknown to the participants in the study, its philosophy and focus are present in the school.education, marketization, marketing, internal marketing, human resource management
Performance Improvement in Passive Backscatter Based RFID System with Low DCR Modulations
This paper presents application of the low Duty Cycle Ratio (DCR) modulations: isochronous Digital Pulse Position Modulation (DPPM) and anisochronous Digital Pulse Interval Modulation (DPIM) in backscatter based passive RFID communication system. The proposed modulations are compared to commonly used Amplitude Shift Keying (ASK) modulation. Low DCR modulations are customized for data transmission through inductively coupled link between reader and the tag operating at frequency of 13.56 MHz. The RFID system is mathematically formulated and the performances of the tag are evaluated for each modulation. Observed parameters are modulation depth of backscattered signal, voltage-current characteristics of tag rectifier circuit and ripple of rectifier output voltage. The application of proposed low DCR modulation techniques improves the performance of the RFID system by up to 250%
Topologically biased random walk with application for community finding in networks
We present a new approach of topology biased random walks for undirected
networks. We focus on a one parameter family of biases and by using a formal
analogy with perturbation theory in quantum mechanics we investigate the
features of biased random walks. This analogy is extended through the use of
parametric equations of motion (PEM) to study the features of random walks {\em
vs.} parameter values. Furthermore, we show an analysis of the spectral gap
maximum associated to the value of the second eigenvalue of the transition
matrix related to the relaxation rate to the stationary state. Applications of
these studies allow {\em ad hoc} algorithms for the exploration of complex
networks and their communities.Comment: 8 pages, 7 figure
Detecting Pair-Instability Supernovae at z<5 with the James Webb Space Telescope
Pair-instability supernovae (PISNe) are the ultimate cosmic lighthouses,
capable of being observed at z<25 and revealing the properties of primordial
stars at cosmic dawn. But it is now understood that the spectra and light
curves of these events evolved with redshift as the universe became polluted
with heavy elements because chemically enriched stars in this mass range
typically lose most of their hydrogen envelopes and explode as bare helium
cores. The light curves of such transients can be considerably dimmer in the
near infrared (NIR) today than those of primordial PISNe of equal energy and
progenitor mass. Here, we calculate detection rates for PISNe whose progenitors
lost their outer layers to either line-driven winds or rotation at z<10, their
detection limit in redshift for the James Webb Space Telescope (JWST). We find
that JWST may be able to detect only Pop II (metal-poor) PISNe over the
redshift range of z<4, but not their Pop III (metal-free) counterparts.Comment: Accepted for ApJ, in pres
Modelling of marketing strategies for the single markets vs marketing strategy for the global market: Case study mobiExplore
A successful treating of a single, national, market through new challenges of marketing management is notably different than treating of the global market. The paper provides the case study of Gideon Multimedia, IT firm from Croatia. The company’s main product is mobiExplore, touristic guide platform for mobile phones. The application could be adapted to different marketplaces - global and national, for different countries. Because of different dynamic of the growth of national mobile markets even the global marketing strategy for the mobiExplore applications needs to be adapted to each national case. Establishing of the national strategy needs to be adapted through market research of the local market. The paper argues that customized for UK market mobiExplore solutions has proved correct and indicate on advantages of the company’s marketing strategies for single market.Marketing, strategies, product, tourism, mobiExplore., Marketing, L86, M30,
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