1,452 research outputs found
Hot electron currents in MOSFETs.
Silicon has become the material of choice for fabrication of high circuit density, low defect density and high speed integration devices. CMOS technology has been favoured as an attractive candidate to take advantage of the performance enhancements available through miniturisation. However, hot carrier effects in general, and hot electron currents in particular, are posing as the main obstacle to a new era of sub-micron architecture in semiconductor device technology. Electron transport in modern sub-micron device is often governed by mechanisms that were not relevant to long-channel devices. Many of the classical device models are based upon such convenient assumptions as "thermal equilibrium" and "uniform local electric field". With the downscaling of devices, hot electron currents are becoming increasingly inherent. These currents arise from the fact that electrical fields in small geometry devices can reach very high values and can vary rapidly in space. The large electric field can Impart significant kinetic energies to the carriers. In thermal equilibrium, all elementary excitations in a semiconductor (eg. Electrons, holes, phonons) can be characterised by a temperature that is the same as the lattice temperature. Under the influence of large electric fields, however, the distribution function of these elementally excitations deviate from those in thermal equilibrium. The term "Hot Carriers" is often used to describe these non-equilibrium situations. In this thesis hot electron currents, in particular their physical origins and dependence upon various operational and geometrical parameters, have been discussed and then quantified in a number of models based on the "Lucky Drift" theory of transport. Temperature is then used as a tool to differentiate between the underlying physical processes, and to determine if reliability problems related to hot electron effects would improve under cryogenic operation. It has been the prime objective of this work from the outset to concentrate on the study of N-channel devices. This is primarily due to the fact that N-channel MOSFET's are more prone to hot electron effects, and therefore, studies in the nature of this enhanced susceptibility could prove to be more fruitful
Generalized shuffles related to Nijenhuis and TD-algebras
Shuffle and quasi-shuffle products are well-known in the mathematics
literature. They are intimately related to Loday's dendriform algebras, and
were extensively used to give explicit constructions of free commutative
Rota-Baxter algebras. In the literature there exist at least two other
Rota-Baxter type algebras, namely, the Nijenhuis algebra and the so-called
TD-algebra. The explicit construction of the free unital commutative Nijenhuis
algebra uses a modified quasi-shuffle product, called the right-shift shuffle.
We show that another modification of the quasi-shuffle product, the so-called
left-shift shuffle, can be used to give an explicit construction of the free
unital commutative TD-algebra. We explore some basic properties of TD-operators
and show that the free unital commutative Nijenhuis algebra is a TD-algebra. We
relate our construction to Loday's unital commutative dendriform trialgebras,
including the involutive case. The concept of Rota-Baxter, Nijenhuis and
TD-bialgebras is introduced at the end and we show that any commutative
bialgebra provides such objects.Comment: 20 pages, typos corrected, accepted for publication in Communications
in Algebr
Complications leading to hospitalization due to consumption of anti-TB drugs in patients with tuberculosis in Gorgan, Iran (2007-12)
Background and Objective: Anti tuberculosis drugs therapy is the most effective method for controling
the tuberculosis (TB). Early detection and appropriate treatment can prevent the TB-drug resistance. This
study was carried out to determine the complications leading to hospitalization due to consumption of
anti-TB drugs in patients with tuberculosis.
Methods: In this descriptive-analytic study, 1550 records of patients with TB in urban and rural health
centers of Gorgan, north of Iran were assessed during 2007-12. Checklist consists of demographic and
clinical data for each patient was recorded in a questionare.
Results: 44 cases experienced the complications of anti-TB drugs. 27 (61.4%) of cases with
complications were women. 77.3% and 22.7% of patients affected with pulmonary and extra pulmonary
tuberculosis,respectively. 38.6% of patients were diabetic. The hepatic complication was seen in 37 cases
(84.1%). Skin and other complications were seen in 5 and 2 cases, respectively. There was not any
relationship between drug complications and other disases.
Conclusion: Hepatic damage is the most common complication leading to hospitalization in tuberculosis
patients using anti-TB drugs.
Keywords: Tuberculosis, Anti-TB drug, Live
Rota-Baxter algebras and new combinatorial identities
The word problem for an arbitrary associative Rota-Baxter algebra is solved.
This leads to a noncommutative generalization of the classical Spitzer
identities. Links to other combinatorial aspects, particularly of interest in
physics, are indicated.Comment: 8 pages, improved versio
Renormalization: a quasi-shuffle approach
In recent years, the usual BPHZ algorithm for renormalization in perturbative
quantum field theory has been interpreted, after dimensional regularization, as
a Birkhoff decomposition of characters on the Hopf algebra of Feynman graphs,
with values in a Rota-Baxter algebra of amplitudes. We associate in this paper
to any such algebra a universal semi-group (different in nature from the
Connes-Marcolli "cosmical Galois group"). Its action on the physical amplitudes
associated to Feynman graphs produces the expected operations: Bogoliubov's
preparation map, extraction of divergences, renormalization. In this process a
key role is played by commutative and noncommutative quasi-shuffle bialgebras
whose universal properties are instrumental in encoding the renormalization
process
Exponential renormalization
Moving beyond the classical additive and multiplicative approaches, we
present an "exponential" method for perturbative renormalization. Using Dyson's
identity for Green's functions as well as the link between the Faa di Bruno
Hopf algebra and the Hopf algebras of Feynman graphs, its relation to the
composition of formal power series is analyzed. Eventually, we argue that the
new method has several attractive features and encompasses the BPHZ method. The
latter can be seen as a special case of the new procedure for renormalization
scheme maps with the Rota-Baxter property. To our best knowledge, although very
natural from group-theoretical and physical points of view, several ideas
introduced in the present paper seem to be new (besides the exponential method,
let us mention the notions of counterfactors and of order n bare coupling
constants).Comment: revised version; accepted for publication in Annales Henri Poincar
Mixable Shuffles, Quasi-shuffles and Hopf Algebras
The quasi-shuffle product and mixable shuffle product are both
generalizations of the shuffle product and have both been studied quite
extensively recently. We relate these two generalizations and realize
quasi-shuffle product algebras as subalgebras of mixable shuffle product
algebras. As an application, we obtain Hopf algebra structures in free
Rota-Baxter algebras.Comment: 14 pages, no figure, references update
Challenges and Benefits of D4AR – 4 Dimensional Augmented Reality - Modeling on the Milano Bicocca Housing Project,
Cloning and expression of codon-optimized recombinant darbepoetin alfa in Leishmania tarentolae T7-TR
Darbepoetin alfa is an engineered and hyperglycosylated analog of recombinant human erythropoietin (EPO) which is used as a drug in treating anemia in patients with chronic kidney failure and cancer. This study desribes the secretory expression of a codon-optimized recombinant form of darbepoetin alfa in Leishmania tarentolae T7-TR. Synthetic codon-optimized gene was amplified by PCR and cloned into the pLEXSY-I-blecherry3 vector. The resultant expression vector, pLEXSYDarbo, was purified, digested, and electroporated into the L. tarentolae. Expression of recombinant darbepoetin alfa was evaluated by ELISA, reverse-transcription PCR (RT-PCR), Western blotting, and biological activity. After codon optimization, codon adaptation index (CAI) of the gene raised from 0.50 to 0.99 and its GC content changed from 56 to 58. Expression analysis confirmed the presence of a protein band at 40 kDa. Furthermore, reticulocyte experiment results revealed that the activity of expressed darbepoetin alfa was similar to that of its equivalent expressed in Chinese hamster ovary (CHO) cells. These data suggested that the codon optimization and expression in L. tarentolae host provided an efficient approach for high level expression of darbepoetin alfa. © 2015 Elsevier Ltd. All rights reserved
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