5,716 research outputs found
A Complete Characterization of the Gap between Convexity and SOS-Convexity
Our first contribution in this paper is to prove that three natural sum of
squares (sos) based sufficient conditions for convexity of polynomials, via the
definition of convexity, its first order characterization, and its second order
characterization, are equivalent. These three equivalent algebraic conditions,
henceforth referred to as sos-convexity, can be checked by semidefinite
programming whereas deciding convexity is NP-hard. If we denote the set of
convex and sos-convex polynomials in variables of degree with
and respectively, then our main
contribution is to prove that if and
only if or or . We also present a complete
characterization for forms (homogeneous polynomials) except for the case
which is joint work with G. Blekherman and is to be published
elsewhere. Our result states that the set of convex forms in
variables of degree equals the set of sos-convex forms if
and only if or or . To prove these results, we present
in particular explicit examples of polynomials in
and
and forms in
and , and a
general procedure for constructing forms in from nonnegative but not sos forms in variables and degree .
Although for disparate reasons, the remarkable outcome is that convex
polynomials (resp. forms) are sos-convex exactly in cases where nonnegative
polynomials (resp. forms) are sums of squares, as characterized by Hilbert.Comment: 25 pages; minor editorial revisions made; formal certificates for
computer assisted proofs of the paper added to arXi
Cosmological constant influence on cosmic string spacetime
We investigate the line element of spacetime around a linear cosmic string in
the presence of a cosmological constant. We obtain the metric and argue that it
should be discarded because of asymptotic considerations. Then a time dependent
and consistent form of the metric is obtained and its properties are discussed.Comment: 3 page
Proving Craig and Lyndon Interpolation Using Labelled Sequent Calculi
We have recently presented a general method of proving the fundamental
logical properties of Craig and Lyndon Interpolation (IPs) by induction on
derivations in a wide class of internal sequent calculi, including sequents,
hypersequents, and nested sequents. Here we adapt the method to a more general
external formalism of labelled sequents and provide sufficient criteria on the
Kripke-frame characterization of a logic that guarantee the IPs. In particular,
we show that classes of frames definable by quantifier-free Horn formulas
correspond to logics with the IPs. These criteria capture the modal cube and
the infinite family of transitive Geach logics
Pemberdayaan Masyarakat Marannu melalui Pertanian dan Peternakan Terintegrasi dalam Rangka Mewujudkan Kabupaten Pinrang sebagai Poros Utama Pemenuhan Pangan Nasional
Tujuan kegiatan ini yaitu Penumbuhkan empati, jiwa kepemimpinan, kewirausahaan, kerja sama mahasiswa, dan dapat memberikan sumbangan bagi penyelesaian persoalan yang ada di masyarakat. Secara Khusus kegiatan ini bertujuan untuk meningkatkan kualitas dan kuantitas produksi pertanian dan peternakan dengan menghasilkan pakan ternak dari pengolahan limbah pertanian dan pupuk organik dari pengolahan limbah peternakan. Metode Pelaksanaan yang diterapkan untuk mencapai tujuan yaitu (1) Sosialisasi Pertanian: Penggunaan pupuk organik dan bahaya penggunaan pupuk kimia, (2) Sosialisasi Peternakan: Pemenuhan gisi dan pemberian vaksin ternak, (3) Pengolahan limbah pertanian menjadi pakan ternak, (4) Pengolahan limbah peternakan menjadi pupuk organik, dan (5) Pemberdayaan masyarakat pengangguran dalam pengolahan pupuk organik dan pakan ternak, Hasil (Luaran) dalam kegiatan ini adalah (1) Meningkatkannya hasil panen pertanian dari jumlah hasil panen sebelumnya, (2) Terjadinya penurunan biaya produksi atau pembelian pakan ternak dari periode sebelumnya dan (3) 50% petani Desa marannu menggunakan pupuk organik hasil pengolahan Limbah dan Peternakan 50% Peternak Desa Marannu menggunakan pakan ternak hasil pengolahan limbah pertanian. Konsep pertanian dan peternakan terintegrasi sebagai langkah Kabupaten Pinrang Sebagai Poros Utama Pemenuhan Pangan Nasiona
Teleparallel Energy-Momentum Distribution of Static Axially Symmetric Spacetimes
This paper is devoted to discuss the energy-momentum for static axially
symmetric spacetimes in the framework of teleparallel theory of gravity. For
this purpose, we use the teleparallel versions of Einstein, Landau-Lifshitz,
Bergmann and Mller prescriptions. A comparison of the results shows
that the energy density is different but the momentum turns out to be constant
in each prescription. This is exactly similar to the results available in
literature using the framework of General Relativity. It is mentioned here that
Mller energy-momentum distribution is independent of the coupling
constant . Finally, we calculate energy-momentum distribution for the
Curzon metric, a special case of the above mentioned spacetime.Comment: 14 pages, accepted for publication in Mod. Phys. Lett.
Probing Micro-quasars with TeV Neutrinos
The jets associated with Galactic micro-quasars are believed to be ejected by
accreting stellar mass black-holes or neutron stars. We show that if the energy
content of the jets in the transient sources is dominated by electron-proton
plasma, then a several hour outburst of 1--100 TeV neutrinos produced by photo-
meson interactions should precede the radio flares associated with major
ejection events. Several neutrinos may be detected during a single outburst by
a 1km^2 detector, thereby providing a powerful probe of micro-quasars jet
physics.Comment: Accepted to PRL. More detailed discussion of particle acceleratio
Duel and sweep algorithm for order-preserving pattern matching
Given a text and a pattern over alphabet , the classic exact
matching problem searches for all occurrences of pattern in text .
Unlike exact matching problem, order-preserving pattern matching (OPPM)
considers the relative order of elements, rather than their real values. In
this paper, we propose an efficient algorithm for OPPM problem using the
"duel-and-sweep" paradigm. Our algorithm runs in time in
general and time under an assumption that the characters in a string
can be sorted in linear time with respect to the string size. We also perform
experiments and show that our algorithm is faster that KMP-based algorithm.
Last, we introduce the two-dimensional order preserved pattern matching and
give a duel and sweep algorithm that runs in time for duel stage and
time for sweeping time with preprocessing time.Comment: 13 pages, 5 figure
CLIMATE CHANGE IMPACT ON MOUNTAIN BIODIVERSITY: A SPECIAL REFERENCE TO GILGIT-BALTISTAN OF PAKISTAN
Climate Change is not a stationary phenomenon; it moves from time to time, it represents a major threat to mountainous biodiversity and to ecosystem integrity. The present study is an attempt to identify the current knowledge gap and the effects of climate change on mountainous biodiversity, a special reference to the Gilgit-Baltistan is briefly reviewed. Measuring the impact of climate change on mountain biodiversity is quite challenging, because climate change interacts with every phenomenon of ecosystem. The scale of this change is so large and very adverse so strongly connected to ecosystem services, and all communities who use natural resources. This study aims to provide the evidences on the basis of previous literature, in particular context to mountain biodiversity of Gilgit-Baltistan (GB). Mountains of Gilgit-Baltistan have most fragile ecosystem and are more vulnerable to climate change. These mountains host variety of wild fauna and flora, with many endangered species of the world. There are still many gaps in our knowledge of literature we studied because very little research has been conducted in Gilgit-Baltistan about climate change particular to biodiversity. Recommendations are made for increased research efforts in future this including jointly monitoring programs, climate change models and ecological research. Understanding the impact of climate change particular to biodiversity of GB is very important for sustainable management of these natural resources. The Government organizations, NGOs and the research agencies must fill the knowledge gap, so that it will help them for policy making, which will be based on scientific findings and research based
Preparation and quality control of 177Lu-[tris(1,10-phenanthroline) lutetium(III)] complex for therapy
The 177Lu-[tris(1,10-phenanthroline)lutetium(III)] complex
(177Lu-PQ3) was prepared successfully with high radiochemical
purity (> 99%). Lu-177 chloride was obtained by
thermal neutron flux (4 × 1013 n.cm–2.s–1) of natural Lu2(NO3)3
sample, dissolved in acidic media. The radiochemical yield
was checked by measuring the radiochemical purity of the
177Lu-PQ complex by ITLC (10 mM DTPA, pH = 5, as mobile
phase). The final complex solution was injected intravenously
into wild-type male rats and bio-distribution of the complex
was checked for up to 48 hours. The dose limiting organs
were shown to be the reticulu-endothelial system. The
bio-distribution of the labelled compounds in tumour-bearing
animals is under investigation.
Nuclear Med Rev 2010; 13, 2: 49–5
Suffix Tree of Alignment: An Efficient Index for Similar Data
We consider an index data structure for similar strings. The generalized
suffix tree can be a solution for this. The generalized suffix tree of two
strings and is a compacted trie representing all suffixes in and
. It has leaves and can be constructed in time.
However, if the two strings are similar, the generalized suffix tree is not
efficient because it does not exploit the similarity which is usually
represented as an alignment of and .
In this paper we propose a space/time-efficient suffix tree of alignment
which wisely exploits the similarity in an alignment. Our suffix tree for an
alignment of and has leaves where is the sum of
the lengths of all parts of different from and is the sum of the
lengths of some common parts of and . We did not compromise the pattern
search to reduce the space. Our suffix tree can be searched for a pattern
in time where is the number of occurrences of in and
. We also present an efficient algorithm to construct the suffix tree of
alignment. When the suffix tree is constructed from scratch, the algorithm
requires time where is the sum of the lengths
of other common substrings of and . When the suffix tree of is
already given, it requires time.Comment: 12 page
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