2,365 research outputs found
Noncommutative Plurisubharmonic Polynomials Part II: Local Assumptions
We say that a symmetric noncommutative polynomial in the noncommutative free
variables (x_1, x_2, ..., x_g) is noncommutative plurisubharmonic on a
noncommutative open set if it has a noncommutative complex hessian that is
positive semidefinite when evaluated on open sets of matrix tuples of
sufficiently large size. In this paper, we show that if a noncommutative
polynomial is noncommutative plurisubharmonic on a noncommutative open set,
then the polynomial is actually noncommutative plurisubharmonic everywhere and
has the form p = \sum f_j^T f_j + \sum k_j k_j^T + F + F^T where the sums are
finite and f_j, k_j, F are all noncommutative analytic. In the paper by Greene,
Helton, and Vinnikov, it is shown that if p is noncommutative plurisubharmonic
everywhere, then p has the form above. In other words, the paper by Greene,
Helton, and Vinnikov makes a global assumption while the current paper makes a
local assumption, but both reach the same conclusion. This paper uses a
Gram-like matrix representation of noncommutative polynomials. A careful
analysis of this Gram matrix plus the main theorem in the paper by Greene,
Helton, and Vinnikov ultimately force the form in the equation above.Comment: 26 page
The Stellar Haloes of Massive Elliptical Galaxies III: Kinematics at Large Radius
We present a 2D kinematic analysis out to ~2-5 effective radii (Re) of 33
massive elliptical galaxies with stellar velocity dispersions larger than 150
km/s. Our observations were taken using the Mitchell Spectrograph (formerly
VIRUS-P), a spectrograph with a large 107 x 107 square arcsecond field-of-view
that allows us to construct robust, spatially resolved kinematic maps of the
mean velocity and velocity dispersion for each galaxy extending to at least 2
Re. Using these maps we study the radial dependence of the stellar angular
momentum and other kinematic properties. We see the familiar division between
slow and fast rotators persisting out to large radius in our sample. Centrally
slow rotating galaxies, which are almost universally characterised by some form
of kinematic decoupling or misalignment, remain slowly rotating in their halos.
The majority of fast rotating galaxies show either increases in specific
angular momentum outwards or no change beyond . The generally triaxial
nature of the slow rotators suggests that they formed through mergers,
consistent with a "two-phase" picture of elliptical galaxy formation. However,
we do not observe the sharp transitions in kinematics proposed in the
literature as a signpost of moving from central dissipationally-formed
components to outer accretion-dominated haloes.Comment: 19 pages, 13 figures. 17 Appendix pages, 19 Appendix figure
All Along the Ivory Tower: Black American Identity as Voiced by Poetic Youths
The purpose of the current study was to help amplify and analyze Black American elementary student voice in a post-2020 world. Discussions and writings were conducted at the studentsâ charter school in spaces where students voiced what it meant to be a Black American youth through both verbal and written means. The current qualitative study focused on using discussions and creative writing to help participants make sense of their identity in their school, community, and the United States. This research provided studentsâ counternarratives regarding stereotypes associated with being Black American students and focused on how such spaces can positively impact Black American students. The current study used a narrative inquiry via youth participatory action research with critical race theory serving as its theoretical framework. Additionally, the current study also addressed development of critical consciousness as interpreted from a nigrescence framework. When discussing the Black American experience in predominantly White spaces, an analysis of themes revealed fourth- and fifth-grade Black American student participants felt personality mattered most when defining oneself as a Black American. Participants also discussed themes related to both racial battle fatigue and an awareness of how their Blackness in predominantly White spaces had been racially profiled and policed. Participants discussed the United Statesâ historically violent nature toward Black Americans, wanting to be representatives of representation in predominantly White careers, a desire for equitable treatment from White adults, and an appreciation for trusted adult allies. Through it all, participants noted a desire for changes in their communities and an overall appreciation for engaging in the work with one another also came forth. Findings suggested elementary-aged Black American students wish to work in community with one another and want to share information regarding their experiences to assist educators in cultivating more welcoming spaces in their school communities and beyond
A NEW READING OF THE LATINâARAMAIC NESES BILINGUAL (IDR III1 167 = PAT 0994), ARAMAIC LINE 2
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Is an Ounce of Prevention Worth an Ounce of Cure? Explaining the Decline in Cardiovascular Mortality, 1964-2010
Mortality from coronary heart disease in the United States has fallen 60% from its peak. Cardiologists and epidemiologists have debated whether this decline reflects risk factor control or the power of medical therapeutics. Attempts to resolve this debate and guide health policy have generated sophisticated datasets and techniques for modeling cardiovascular mortality. Neither effort, however, has provided specific guidance for health policy. Historical analysis of the decline debate and the development of cardiovascular modeling offers valuable lessons for policymakers about tensions between medical and public health strategies, the changing meanings of disease prevention, and ability of evidence-based research and models to guide health policy. Policymakers must learn to open up the black box of epidemiological models -- and of their own decision making processes -- to produce the best evidence-informed policy.History of Scienc
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The Decline and Rise of Coronary Heart Disease: Understanding Public Health Catastrophism
The decline of coronary heart disease mortality in the United States and Western Europe is one of the great accomplishments of modern public health and medicine. Cardiologists and cardiovascular epidemiologists have devoted significant effort to disease surveillance and epidemiological modeling to understand its causes. One unanticipated outcome of these efforts has been the detection of early warnings that the decline had slowed, plateaued, or even reversed. These subtle signs have been interpreted as evidence of an impending public health catastrophe. This article traces the history of research on coronary heart disease decline and resurgence and situates it in broader narratives of public health catastrophism. Juxtaposing the coronary heart disease literature alongside the narratives of emerging and reemerging infectious disease helps to identify patterns in how public health researchers create data and craft them into powerful narratives of progress or pessimism. These narratives, in turn, shape public health policy.History of ScienceOther Research Uni
Sugarcane Aphid as a Pest of Sorghum
A new pest of grain and forage sorghum, the sugarcane aphid (Melanaphis sacchari), was found for the first time in South Carolina in October 2014. The insect rapidly became a key pest of sorghum. This publication provides an overview of the insectâs biology and recommended management practices.
Melanaphis sacchar
Considering armed violence in the post-conflict transition: DDR and small arms and light weapons reduction initiatives
This briefing paper seeks to increase awareness of and review the linkages between disarmament, demobilisation and reintegration (DDR) and small arms and light weapons (SALW) reduction in the context of post-conflict reconstruction (PCR). It is targeted at those working on poverty reduction at both the policy and programme level, particularly those with comparatively modest engagement in these areas. Its objective is to outline the types of activities that have been undertaken under these rubrics, the difficulties and constraints encountered at the level of implementation, and, in particular, to identify opportunities in linking SALW programmes and DDR. It also seeks to highlight the problems created by widespread arms availability and usage in PCR. This briefing paper is not intended as a comprehensive review of the state of DDR/SALW/PCR programming and policy, but rather an introduction to some of the core issues
Noncommutative Plurisubharmonic Polynomials Part I: Global Assumptions
We consider symmetric polynomials, p, in the noncommutative free variables
(x_1, x_2, ..., x_g). We define the noncommutative complex hessian of p and we
call a noncommutative symmetric polynomial noncommutative plurisubharmonic if
it has a noncommutative complex hessian that is positive semidefinite when
evaluated on all tuples of n x n matrices for every size n. In this paper, we
show that the symmetric noncommutative plurisubharmonic polynomials are
precisely the noncommutative convex polynomials with a noncommutative analytic
change of variables; i.e., a noncommutative symmetric polynomial, p, is
noncommutative plurisubharmonic if and only if it has the form p = \sum f_j^T
f_j + \sum k_j k_j^T + F + F^T where the sums are finite and f_j, k_j, F are
all noncommutative analytic. We also present a theory of noncommutative
integration for noncommutative polynomials and we prove a noncommutative
version of the Frobenius theorem. A subsequent paper by Greene proves that if
the noncommutative complex hessian of p takes positive semidefinite values on a
"noncommutative open set" then the noncommutative complex hessian takes
positive semidefinite values on all matrix tuples. Thus, p has the form above.
The proof in the subsequent paper draws on most of the theorems in this paper
together with a very different technique involving representations of
noncommutative quadratic functions.Comment: 24 page
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