7,098 research outputs found
Cryptophagids from the Maltese Islands with description of a new species of Micrambe THOMSON (Coleoptera: Cryptophagidae)
The Cryptophagidae (Coleoptera) of the Maltese Islands are reviewed based on material of earlier records and recent collections. A total of twelve species are reported, of which Micrambe mediterranica OTERO & JOHNSON sp.n. is described from material collected in Malta, Greece and Jordan.peer-reviewe
The NIEP
The nonnegative inverse eigenvalue problem (NIEP) asks which lists of
complex numbers (counting multiplicity) occur as the eigenvalues of some
-by- entry-wise nonnegative matrix. The NIEP has a long history and is a
known hard (perhaps the hardest in matrix analysis?) and sought after problem.
Thus, there are many subproblems and relevant results in a variety of
directions. We survey most work on the problem and its several variants, with
an emphasis on recent results, and include 130 references. The survey is
divided into: a) the single eigenvalue problems; b) necessary conditions; c)
low dimensional results; d) sufficient conditions; e) appending 0's to achieve
realizability; f) the graph NIEP's; g) Perron similarities; and h) the
relevance of Jordan structure
Civic Service Worldwide: Defining a Field, Building a Knowledge Base.
In this article, the authors summarize results of a global assessment of civic service. Searching by country and using information from organizational memberships, publications, and the Internet, 210 civic service programs were identified in 57 countries
"The War for the Fare": How Driver Compensation Affects Bus System Performance
Two systems of bus driver compensation exist in Santiago, Chile. Most drivers are paid per passenger transported, while a second system compensates other drivers with a fixed wage. Compared with fixed-wage drivers, per-passenger drivers have incentives to engage in "La Guerra por el Boleto" ("The War for the Fare"), in which drivers change their driving patterns to compete for passengers. This paper takes advantage of a natural experiment provided by the coexistence of these two compensation schemes on similar routes in the same city. Using data on intervals between bus arrivals, we find that the fixed-wage contract leads to more bunching of buses, and hence longer average passenger wait times. The per-passenger drivers are assisted by a group of independent information intermediaries called "sapos" who earn their living by standing at bus stops, recording arrival times, and selling the information to subsequent drivers who drive past. We find that a typical bus passenger in Santiago waits roughly 10% longer for a bus on a fixed-wage route relative to an incentive-contract route. However, the incentives also lead drivers to drive noticeably more aggressively, causing approximately 67% more accidents per kilometer driven. Our results have implications for the design of incentives in public transportation systems.
Singularities of free group character varieties
Let X be the moduli space of SL(n,C), SU(n), GL(n,C), or U(n)-valued
representations of a rank r free group. We classify the algebraic singular
stratification of X. This comes down to showing that the singular locus
corresponds exactly to reducible representations if there exist singularities
at all. Then by relating algebraic singularities to topological singularities,
we show the moduli spaces X generally are not topological manifolds, except for
a few examples we explicitly describe.Comment: 33 pages. Version 4 is shorter and more focused; cut material will be
expanded upon and written up in subsequent papers. Clarifications, and
expository revisions have been added. Accepted for publication in Pacific
Journal of Mathematic
Designing libraries for pooled CRISPR functional screens of long noncoding RNAs.
Human and other genomes encode tens of thousands of long noncoding RNAs (lncRNAs), the vast majority of which remain uncharacterised. High-throughput functional screening methods, notably those based on pooled CRISPR-Cas perturbations, promise to unlock the biological significance and biomedical potential of lncRNAs. Such screens are based on libraries of single guide RNAs (sgRNAs) whose design is critical for success. Few off-the-shelf libraries are presently available, and lncRNAs tend to have cell-type-specific expression profiles, meaning that library design remains in the hands of researchers. Here we introduce the topic of pooled CRISPR screens for lncRNAs and guide readers through the three key steps of library design: accurate annotation of transcript structures, curation of optimal candidate sets, and design of sgRNAs. This review is a starting point and reference for researchers seeking to design custom CRISPR screening libraries for lncRNAs
Species of Cryptophagus Herbst, 1792, belonging to the “dentatus group” (Coleopera: Cryptophagidae) from the Western Palearctic region
Eight species of the genus Cryptophagus Herbst, 1792, belonging to the “dentatus group” from the Palearctic Region are revised. The opinions of different authors about the value of the characteristics of the external anatomy are contrasted, and an identification key and figures of the studied species are presented
Multicultural/Multiethnic Education: A Critical Approach to the Educational Doctorate in Leadership
In the coming years, the community college will experience unprecedented turnover in its leadership, especially among its senior ranks (Shults, 2001; Weisman & Vaughan, 2001; 2006). Weisman & Vaughan (2006) note that 84 percent of community college Chief Executive Officers (CEOs) plan to retire by 2016. Primarily, the ‘impending’ leadership void is being created by educators who entered the community college in the 1960s and 1970s, and have served in these institutions for decades (Phillippe & Sullivan, 2005; Schults, 2001). On the verge of retirement, the presidential ranks are becoming progressively older. In 1996, the average age of a community college president was 54; in 2001, it had risen to 56. By 2006, the average age of a president had increased to 58 (Weisman & Vaughan, 2006). While the average age of a community college president is 58, Duree (2007) notes that 44 percent of presidents are between the ages of 60 and 69, supporting the assertion that administrator turnover is forthcoming
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