9,275 research outputs found
Selective extinction of marine plankton at the end of the Mesozoic era: The fossil and stable isotope record
Floral, faunal and stable isotope evidence in a continuous sequence of latest Cretaceous and earliest Tertiary shallow water marine deposits in the Mangyshlak Peninsula, USSR suggest severe environmental changes at the Cretaceous/Tertiary (K/T) boundary. Time frame is provided by nanno, micro and macrofossils as well as by magnetic stratigraphy and an iridium spike. Oxygen isotopic analyses of the bulk sediments, composed of nanno and microplankton skeletal remains, show a sharp positive spike at the K/T boundary. This shift is primarily attributed to severe cooling possibly accompanied by increased salinities of the surface mixed layer. Floral and faunal extinctions were selective, affecting approximately 90 percent of the warm water calcareous phyto and zooplankton genera in the Tethyan-Paratethyan regions. These highly diverse taxa with many endemic representatives were at the peak of their evolutionary development. Geologic evidence indicates that the terminal Cretaceous temperature decline was coeval with widespread and intense volcanic activity which reached a peak at the close of the Mesozoic Era. Increased acidity temporarily prohibited calcite nucleation of the surface dwelling warm-water plankton. Superimposed upon decreased alkalinity, severe and rapid climatic changes caused the extinction of calcareous phyto and zooplankton
Linear Superiorization for Infeasible Linear Programming
Linear superiorization (abbreviated: LinSup) considers linear programming
(LP) problems wherein the constraints as well as the objective function are
linear. It allows to steer the iterates of a feasibility-seeking iterative
process toward feasible points that have lower (not necessarily minimal) values
of the objective function than points that would have been reached by the same
feasiblity-seeking iterative process without superiorization. Using a
feasibility-seeking iterative process that converges even if the linear
feasible set is empty, LinSup generates an iterative sequence that converges to
a point that minimizes a proximity function which measures the linear
constraints violation. In addition, due to LinSup's repeated objective function
reduction steps such a point will most probably have a reduced objective
function value. We present an exploratory experimental result that illustrates
the behavior of LinSup on an infeasible LP problem.Comment: arXiv admin note: substantial text overlap with arXiv:1612.0653
On universal partial words
A universal word for a finite alphabet and some integer is a
word over such that every word in appears exactly once as a subword
(cyclically or linearly). It is well-known and easy to prove that universal
words exist for any and . In this work we initiate the systematic study
of universal partial words. These are words that in addition to the letters
from may contain an arbitrary number of occurrences of a special `joker'
symbol , which can be substituted by any symbol from . For
example, is a linear partial word for the binary alphabet
and for (e.g., the first three letters of yield the
subwords and ). We present results on the existence and
non-existence of linear and cyclic universal partial words in different
situations (depending on the number of s and their positions),
including various explicit constructions. We also provide numerous examples of
universal partial words that we found with the help of a computer
Drug Management Reviews in District Drug Management Unit and General Hospital
Drug is one of the essential elements in healthcare that should be effectively and efficiently managed. Following the decentralization in 2001 in Indonesia, drug management has changed in district drug management units and also in District General Hospitals. Certainly this condition influences the sustainability of drug access in primary health care such as in Community Health Center and District General Hospital, especially in drug financing policy. A cross sectional descriptive study to obtain information on drug management in public healthcare in district had been carried out between July and December 2006 in 10 District Public Drug Management Units from 10 district health offices and 9 district general hospitals as samples. Data were collected by interviewing heads of Drug Section in District Health Offices and heads of Hospital Pharmacies using structured questionnaires and observing drug storage in District Drug Management Units, Community Health Centers, and Hospital Pharmacies. Results of the study show that drug planning in District Health Offices and General Hospitals did not meet the basic real need in some districts nor District Hospitals. The minimum health service standards had not been achieved yet. Furthermore, drug procurement, storage and recording as well as reporting was not good enough either, such as shown by the existence of expired drugs. Lead time for drug delivery to community health centers in some districts was longer than the average of lead time in the past 3 years
Mind and Data Science
Mind and Data Scienc
Networks (of Everything)
Networks (of Everything
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