Comparison between a vector multiport network analyzer and the national S-parameter measurement system

A multiport vector network analyzer based on a new calibration concept, has been compared with the P-port S-parameter National measurement system at IENGF. The measurements were performed on precision 7 mm standard components and exhibited an optimum agreement. These results open the possibility to use the new multiport network analyzer for certification measurements of multiport device

Accuracy of a multiport network analyzer

The accuracy of a multiport vector network analyzer, which uses a new calibration concept, has been compared with a 2-port network analyzer that implements the classical TRL procedure. The accuracy assessment is based on the analysis of the error propagation due to the connectors repeatability, both of the used standards and the measurands. The comparison, performed in the 2-18 GHz band on devices fitted with APC-7 mm connectors, proved the high accuracy reached by a multiport system which can qualify for metrological applications

Symptomatic seizures in preterm newborns: a review on clinical features and prognosis

Neonatal seizures are the most common neurological event in newborns, showing higher prevalence in preterm than in full-term infants. In the majority of cases they represent acute symptomatic phenomena, the main etiologies being intraventricular haemorrhage, hypoxic-ischemic encephalopathy, central nervous system infections and transient metabolic derangements.Current definition of neonatal seizures requires detection of paroxysmal EEG-changes, and in preterm newborns the incidence of electrographic-only seizures seems to be particularly high, further stressing the crucial role of electroencephalogram monitoring in this population. Imaging work-up includes an integration of serial cranial ultrasound and brain magnetic resonance at term-equivalent age. Unfavourable outcomes following seizures in preterm infants include death, neurodevelopmental impairment, epilepsy, cerebral palsy, hearing and visual impairment. As experimental evidence suggests a detrimental role of seizures per se in determining subsequent outcome, they should be promptly treated with the aim to reduce seizure burden and long-term disabilities. However, neonatal seizures show low response to conventional anticonvulsant drugs, and this is even more evident in preterm newborns, due to intrinsic developmental factors. As a consequence, as literature does not provide any specific guidelines, due to the lack of robust evidence, off-label medications are often administered in clinical practice

On the algebraic structure of rotationally invariant two-dimensional Hamiltonians on the noncommutative phase space

We study two-dimensional Hamiltonians in phase space with noncommutativity both in coordinates and momenta. We consider the generator of rotations on the noncommutative plane and the Lie algebra generated by Hermitian rotationally invariant quadratic forms of noncommutative dynamical variables. We show that two quantum phases are possible, characterized by the Lie algebras $sl(2,\mathbb{R})$ or $su(2)$ according to the relation between the noncommutativity parameters, with the rotation generator related with the Casimir operator. From this algebraic perspective, we analyze the spectrum of some simple models with nonrelativistic rotationally invariant Hamiltonians in this noncommutative phase space, as the isotropic harmonic oscillator, the Landau problem and the cylindrical well potential. PACS: 03.65.-w; 03.65.Fd MSC: 81R05; 20C35; 22E70Comment: 49 pages. No figures. Version to appear in JP

Boundaries in the Moyal plane

We study the oscillations of a scalar field on a noncommutative disc implementing the boundary as the limit case of an interaction with an appropriately chosen confining background. The space of quantum fluctuations of the field is finite dimensional and displays the rotational and parity symmetry of the disc. We perform a numerical evaluation of the (finite) Casimir energy and obtain similar results as for the fuzzy sphere and torus.Comment: 19 pages, 6 figures. Replaced by published versio

Monitoring of newborns at high risk for brain injury

Due to the increasing number of surviving preterm newborns and to the recognition of therapeutic hypothermia as the current gold standard in newborns with hypoxic-ischaemic encephalopathy, there has been a growing interest in the implementation of brain monitoring tools in newborns at high risk for neurological disorders. Among the most frequent neurological conditions and presentations in the neonatal period, neonatal seizures and neonatal status epilepticus, paroxysmal non-epileptic motor phenomena, hypoxic-ischaemic encephalopathy, white matter injury of prematurity and stroke require specific approaches to diagnosis. In this review we will describe the characteristics, aims, indications and limitations of routinely available diagnostic techniques such as conventional and amplitude-integrated EEG, evoked potentials, cranial ultrasound and brain MRI. We will conclude by briefly outlining potential future perspectives from research studies

Evidence that an archaeal alpha-like DNA polymerase has a modular organization of its associated catalytic activities.

In this study we report on the evidence that an alpha-like DNA polymerase purified from the thermoacidophilic archaeon Sulfolobus solfataricus has a modular organization of its associated catalytic activities (polymerase and 3'-5' exonuclease). This enzyme, a monomer of about 100 kDa whose complete primary structure is available, has a protease hypersensitive site that is likely to be cleaved by the action of endogenous proteases during the purification procedure. As a consequence of that, two proteolytic fragments of about 50 and 40 kDa, in addition to the intact 100-kDa molecular species, can be detected upon SDS-PAGE of highly purified S. solfataricus DNA polymerase samples. The amino-terminal microsequence analysis by Edman degradation has revealed that the 50- and the 40-kDa polypeptides correspond to the carboxyl- and the amino-terminal portion of the protein molecule, respectively. Using the bidimensional activity gel assay procedure, recently described by Longley and Mosbaugh (Longley, M. J., and Mosbaugh, D. W. (1991) Biochemistry 30, 2655-2664), we have demonstrated that the 50-kDa fragment retains a Mg(2+)-dependent DNA polymerizing activity, whereas the 40-kDa polypeptide is able to catalyze the excision of mispaired nucleotides at the 3'-OH terminus of a primer/template DNA substrate in the presence of Mn2+ ions. On the other hand, the 100-kDa protein possess both activities. To date, this is the first report indicating, on the basis of direct functional data, that the polymerization and the 3'-5' exonuclease activity of a family B DNA polymerase can be ascribed to physically distinct modules of the enzyme molecule

Calcium transport in gill cells of Ucides cordatus, a mangrove crab living in variable salinity environments

Crustaceans show discontinuous growth and have been used as a model system for studying cellular mechanisms of calcium transport, which is the main mineral found in their exoskeleton. Ucides cordatus, a mangrove crab, is naturally exposed to fluctuations in calcium and salinity. To study calcium transport in this species during isosmotic conditions, dissociated gill cells were marked with fluo-3 and intracellular Ca2+ change was followed by adding extracellular Ca2+ as CaCl2 (0, 0.1, 0.25, 0.50, 1.0 and 5 mM), together with different inhibitors. for control gill cells, Ca2+ transport followed Michaelis-Menten kinetics with V-max = 0.137 +/- 0.001 Delta Ca(2+)i (mu M x 22.10(4) cells(-1) x 180 s(-1); N = 4; r(2) = 0.99); K-m = 0.989 +/- 0.027 mM. the use of different inhibitors for gill cells showed that amiloride (Na+/Ca2+ exchange inhibitor) inhibited 80% of Ca2+ transport in gill cells (V-max). KB-R, an inhibitor of Ca influx in vertebrates, similarly caused a decrease in Ca2+ transport and verapamil (Ca2+ channel inhibitor) had no effect on Ca2+ transport, while nifedipine (another Ca2+ channel inhibitor) caused a 20% decrease in Ca2+ affinity compared to control values. Ouabain, on the other hand, caused no change in Ca2+ transport while vanadate increased the concentration of intracellular calcium through inhibition of Ca2+ efflux probably through the plasma membrane Ca2+-ATPase. Results show that transport kinetics for Ca2+ in these crabs under isosmotic conditions is lower compared to a hyper-regulator freshwater crab Dilocarcinus pagei studied earlier using fluorescent Ca2+ probes. These kinds of studies will help understanding the comparative mechanisms underlying the evolution of Ca transport in crabs living in different environments. (C) 2013 Elsevier Inc. All rights reserved.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Universidade Federal de São Paulo UNIFESP, Dept Renal Physiol, São Paulo, BrazilUniv São Paulo, Inst Biociencias, Dept Physiol, BR-05508900 São Paulo, BrazilUniversidade Federal de São Paulo UNIFESP, Dept Renal Physiol, São Paulo, BrazilFAPESP: FAPESP 2009/15546-3Web of Scienc