San Diego State University

About: San Diego State University is a education organization based out in San Diego, California, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 12418 authors who have published 27950 publications receiving 1192375 citations. The organization is also known as: SDSU & San Diego State College.

The first systematic study of type Ibc supernova multi-band light curves

Abstract: We present detailed optical photometry for 25 Type Ibc supernovae (SNe Ibc) within d 150 Mpc obtained with the robotic Palomar 60 inch telescope in 2004-2007. This study represents the first uniform, systematic, and statistical sample of multi-band SNe Ibc light curves available to date. We correct the light curves for host galaxy extinction using a new technique based on the photometric color evolution, namely, we show that the (V – R) color of extinction-corrected SNe Ibc at Δt 10 days after V-band maximum is tightly distributed, (V – R) V10 = 0.26 ± 0.06 mag. Using this technique, we find that SNe Ibc typically suffer from significant host galaxy extinction, E(B – V) 0.4 mag. A comparison of the extinction-corrected light curves for helium-rich (Type Ib) and helium-poor (Type Ic) SNe reveals that they are statistically indistinguishable, both in luminosity and decline rate. We report peak absolute magnitudes of MR = –17.9 ± 0.9 mag and MR = –18.3 ± 0.6 mag for SNe Ib and Ic, respectively. Focusing on the broad-lined (BL) SNe Ic, we find that they are more luminous than the normal SNe Ibc sample, MR = –19.0 ± 1.1 mag, with a probability of only 1.6% that they are drawn from the same population of explosions. By comparing the peak absolute magnitudes of SNe Ic-BL with those inferred for local engine-driven explosions (GRB-SN 1998bw, XRF-SN 2006aj, and SN 2009bb) we find a 25% probability that relativistic SNe are drawn from the overall SNe Ic-BL population. Finally, we fit analytic models to the light curves to derive typical 56Ni masses of M Ni 0.2 and 0.5 M ☉ for SNe Ibc and SNe Ic-BL, respectively. With reasonable assumptions for the photospheric velocities, we further extract kinetic energy and ejecta mass values of M ej 2 M ☉ and EK 1051 erg for SNe Ibc, while for SNe Ic-BL we find higher values, M ej 5 M ☉ and EK 1052 erg. We discuss the implications for the progenitors of SNe Ibc and their relation to those of engine-driven explosions.

Organizational citizenship behavior in work groups: a group norms approach.

Abstract: Although the relationship between unit-level organizational citizenship behavior (OCB) and unit outcomes has been well established in recent years, the conceptual development of OCB at the unit level of analysis has not been adequately addressed. In an effort to fill this conceptual gap and to spur future research, the authors apply the literature on group norms to the concept of OCB. The resulting framework suggests a cyclical relationship between individual- and group-level processes and ultimately offers an explanation for how OCB norms are established and maintained in work groups. The authors demonstrate how this framework incorporates past research on the relationship between unit-level OCB and unit outcomes and how it extends previous research by suggesting multiple directions for future efforts related to unit-level OCB.

Evaluating Evaluations: The Case of Parent Involvement Programs:

Abstract: This article analyzes 41 studies that evaluated K–12 parent involvement programs in order to assess claims that such programs are an effective means of improving student learning. It examines the characteristics of the parent involvement programs, as well as the research design, data, and analytical techniques used in program evaluation. Our examination of evaluations found little empirical support for the widespread claim that parent involvement programs are an effective means of improving student achievement or changing parent, teacher, and student behavior. We do not conclude that programs are ineffective. Rather, serious design, methodological, and analytical flaws inherent in studies evaluating the effectiveness of parent involvement programs must be addressed before definite conclusions about program effectiveness can be reached. The findings of this study are particularly significant given the substantial federal support for parent involvement.