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Minimal Value (minimal + value)
Selected AbstractsA 3-D dielectrophoretic filter chipELECTROPHORESIS, Issue 7 2007Ciprian Iliescu Dr. Abstract The paper presents a 3-D filter chip employing both mechanical and dielectrophoretic (DEP) filtration, and its corresponding microfabrication techniques. The device structure is similar to a classical capacitor: two planar electrodes, made from a stainless steel mesh, and bonded on both sides of a glass frame filled with round silica beads. The solution with the suspension of particles flows through both the mesh-electrodes and silica beads filter. The top stainless steel mesh (with openings of 60,,m and wires of 30,,m-thickness) provides the first stage of filtration based on mechanical trapping. A second level of filtration is based on DEP by using the nonuniformities of the electric field generated in the capacitor due to the nonuniformities of the dielectric medium. The filter can work also with DC and AC electric fields. The device was tested with yeast cells (Saccharomyces cerevisae) and achieved a maximal trapping efficiency of 75% at an applied AC voltage of 200,V and a flow rate of 0.1,mL/min, from an initial concentration of cells of 5×105 cells/mL. When the applied frequency was varieted in the range between 20 and 200,kHz, a minimal value of capture efficiency (3%) was notticed at 50,kHz, when yeast cells exhibit negative DEP and the cells are repelled in the space between the beads. [source] c - fos and estrogen receptor gene expression pattern in the rat uterine epithelium during the estrous cycleMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 4 2003C. Adriana Mendoza-Rodríguez Abstract Different studies in ovariectomized estrogen treated animals support the idea that c - fos plays a role in the proliferation of uterine epithelial cells. However, these studies invite us to reassess the role played by c - fos in epithelial cell types of the endometrium during the estrous cycle. The present study was undertaken to determine the c - fos and estrogen receptor (ER) gene expression pattern in the rat uterine epithelium during the estrous cycle in which natural and cyclic changes of steroid hormones occur, and correlate these changes with the proliferation status of this cellular types. Proliferation was assessed during the estrous cycle using bromodeoxyuridine incorporation to DNA. ER, and , proteins were assessed by immunohistochemistry. The regulation of c - fos gene expression in the uterus of intact animals during the estrous cycle was evaluated using both in situ hybridization and immunohistochemistry. Estradiol (E2) and progesterone (P4) plasma levels were assessed by radioimmunoassay. The results indicated that luminal (LE) and glandular epithelia (GE) presented maximal proliferation during the metestrus (M) and the diestrus (D) days. However, during the proestrus (P) day only LE presented proliferation, and during the estrus (E) day only the stromal cells proliferated. A marked immunostaining for ER, was detected in both LE and GE cells during the early phases of the cycle but diminished on the P and the E day. In contrast, ER, was undetectable in both epithelia during all stages of the cycle. The highest c - fos mRNA level was detected in both epithelia on the M day, followed by a significant reduction during the other days of the cycle. The highest protein content was observed on the M and D days, and the minimal value was detected on the E day. The c-Fos protein level in LE was increased during M and D days, presenting a high correlation with the cellular proliferation pattern of this cell type. In conclusion, the overall results indicate that c-Fos protein presented a good correlation with uterine epithelial cell proliferation of LE. In the case of GE, the same tendency was observed, although no significant correlation was found. Both in LE and GE, c - fos mRNA did not strictly correlate with its protein levels. c - fos seems to have a postranscriptional regulation in uterine epithelial cells during the rat's estrous cycle. Mol. Reprod. Dev. 64: 379,388, 2003. © 2003 Wiley-Liss, Inc. [source] Observation of charged excitons in V-groove quantum wiresPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 3 2004T. Otterburg Abstract We report on the observation of negatively and positively charged excitons in the photoluminescence spectra of V-groove quantum wires. The charged exciton binding energy increases with the strength of the quantum confinement. We demonstrate that the charged excitons are localized by the fluctuations of the confinement potential and estimate a minimal value of the localization length. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Linear lower bounds for ,c(p) for a class of 2D self-destructive percolation modelsRANDOM STRUCTURES AND ALGORITHMS, Issue 4 2009J. van den Berg Abstract The self-destructive percolation model is defined as follows: Consider percolation with parameter p > pc. Remove the infinite occupied cluster. Finally, give each vertex (or, for bond percolation, each edge) that at this stage is vacant, an extra chance , to become occupied. Let ,c(p) be the minimal value of ,, needed to obtain an infinite occupied cluster in the final configuration. This model was introduced by van den Berg and Brouwer. They showed, for the site model on the square lattice (and a few other 2D lattices satisfying a special technical condition) that ,c(p) , . In particular, ,c(p) is at least linear in p , pc. Although the arguments used by van den Berg and Brouwer look very lattice-specific, we show that they can be suitably modified to obtain similar linear lower bounds for ,c(p) (with p near pc) for a much larger class of 2D lattices, including bond percolation on the square and triangular lattices, and site percolation on the star lattice (or matching lattice) of the square lattice. © 2009 Wiley Periodicals, Inc. Random Struct. Alg., 2009 [source] Nitric oxide-induced biphasic mechanism of vascular relaxation via dephosphorylation of CPI-17 and MYPT1THE JOURNAL OF PHYSIOLOGY, Issue 14 2009Toshio Kitazawa Nitric oxide (NO) from endothelium is a major mediator of vasodilatation through cGMP/PKG signals that lead to a decrease in Ca2+ concentration. In addition, NO-mediated signals trigger an increase in myosin light chain phosphatase (MLCP) activity. To evaluate the mechanism of NO-induced relaxation through MLCP deinhibition, we compared time-dependent changes in Ca2+, myosin light chain (MLC) phosphorylation and contraction to changes in phosphorylation levels of CPI-17 at Thr38, RhoA at Ser188, and MYPT1 at Ser695, Thr696 and Thr853 in response to sodium nitroprusside (SNP)-induced relaxation in denuded rabbit femoral artery. During phenylephrine (PE)-induced contraction, SNP reduced CPI-17 phosphorylation to a minimal value within 15 s, in parallel with decreases in Ca2+ and MLC phosphorylation, followed by a reduction of contractile force having a latency period of about 15 s. MYPT1 phosphorylation at Ser695, the PKG-target site, increased concurrently with relaxation. Phosphorylation of RhoA, MYPT1 Thr696 and Thr853 differed significantly at 5 min but not within 1 min of SNP exposure. Inhibition of Ca2+ release delayed SNP-induced relaxation while inhibition of Ca2+ channel, BKCa channel or phosphodiesterase-5 did not. Pretreatment of resting artery with SNP suppressed an increase in Ca2+, contractile force and phosphorylation of MLC, CPI-17, MYPT1 Thr696 and Thr853 at 10 s after PE stimulation, but had no effect on phorbol ester-induced CPI-17 phosphorylation. Together, these results suggest that NO production suppresses Ca2+ release, which causes an inactivation of PKC and rapid CPI-17 dephosphorylation as well as MLCK inactivation, resulting in rapid MLC dephosphorylation and relaxation. [source] The relationships between half-life (t1/2) and mean residence time (MRT) in the two-compartment open body modelBIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 4 2004Eyal Sobol Abstract Rationale. In the one-compartment model following i.v. administration the mean residence time (MRT) of a drug is always greater than its half-life (t1/2). However, following i.v. administration, drug plasma concentration (C) versus time (t) is best described by a two-compartment model or a two exponential equation: C=Ae,,t+Be,,t, where A and B are concentration unit-coefficients and , and , are exponential coefficients. The relationships between t1/2 and MRT in the two-compartment model have not been explored and it is not clear whether in this model too MRT is always greater than t1/2. Methods. In the current paper new equations have been developed that describe the relationships between the terminal t1/2 (or t1/2,) and MRT in the two-compartment model following administration of i.v. bolus, i.v. infusion (zero order input) and oral administration (first order input). Results. A critical value (CV) equals to the quotient of (1,ln2) and (1,,/,) (CV=(1,ln2)/(1,,/,)=0.307/(1,,/,)) has been derived and was compared with the fraction (f1) of drug elimination or AUC (AUC-area under C vs t curve) associated with the first exponential term of the two-compartment equation (f1=A/,/AUC). Following i.v. bolus, CV ranges between a minimal value of 0.307 (1,ln2) and infinity. As long as f1 Is the forest conversion to pasture affecting the hydrological response of Amazonian catchments?HYDROLOGICAL PROCESSES, Issue 10 2010Signals in the Ji-Paraná Basin Abstract It is well known that land use and land-cover changes (LUCC), particularly deforestation, have the potential to modify the hydrological response. Although those signals are relatively well documented in worldwide microcatchment studies, conflicting results reported in literature indicate that those signals can be sometimes difficult to detect and isolate in basins at larger scales. In order to detect signals in the hydrological response potentially, related to LUCC, streamflow records from Ji-Paraná Basin located in SW Amazonia are analysed in conjunction with deforestation maps derived from remote sensors. The basin has a drainage area greater than 30 000 km2 and has been through severe LUCC in the last decades. Statistical descriptors of daily streamflow series were correlated with landscape indices using non-parametric methodologies. To take into account scale effects, statistical analyses were repeated in different sub-basins. Results showed that the impact of LUCC on the hydrological response is time lagged at larger scales. The flow paths are clearly affected, depending on basin characteristics such as topography. In general, LUCC impacts lead to higher peak streamflows, the reduction of minimal values and the increment of stormflow. In agreement with previous studies, the detection of signals associated with LUCC was clearly detected at the smallest basin, but proved to be difficult at larger scales, suggesting the existence of non-linear effects, which aggregate across scale compensating small scale effects. Such behaviour indicates a challenge for mathematical models, which are usually developed to represent immediate hydrological response to basin wide LUCC. Copyright © 2010 John Wiley & Sons, Ltd. [source] New micromachined interdigital coplanar waveguideMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 5 2007Xiaofeng Sun Abstract A novel interdigital coplanar waveguide (CPW) has been designed and fabricated and its characteristics have been studied as a function of transmission line parameters. In this interdigital CPW, the ground conductors are thickened by micromachining techniques, which are helpful for reducing the interference between the adjacent parallel sections of center conductor. Within the frequency range from 5 to 20 GHz, the return loss of this structure has two minimal values whose positions change with the structural parameters. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1007,1010, 2007; Published online in Wiley InterScience (www.interscience.wiley.com).DOI 10.1002/mop.22336 [source] Effect of chirality on PVP/drug interaction within binary physical mixtures of ibuprofen, ketoprofen, and naproxen: A DSC studyCHIRALITY, Issue 8 2009Ivan T. Ivanov Abstract We report on the thermal behavior of freshly prepared binary drug/polymer physical mixtures that contained ibuprofen, ketoprofen, or naproxen as a drug, and polyvinylpyrrolidone (PVP), hydroxyethylcellulose (HEC), or methylcellulose (MC) as excipient. At 6,10°C/min heating rates the DSC detected a sharp, single endotherm that corresponds to the melting of drug. On heating physical mixtures of PVP and racemic ibuprofen or ketoprofen at lower heating rates, another endotherm was registered in front of the original one. To observe the additional endotherm, specific minimal values of the heating rate and of PVP weight fraction were needed; for ibuprofen and ketoprofen they were 1.5 and 2.0°C/min, and 5 and 15% (w/w), respectively. At greater PVP weight fractions the top temperatures, Tmp, of both peaks were reduced almost linearly indicating strong solid-state interfacial reaction between the drug particles and PVP matrix. The additional endotherm was abolished at greater heating rates (2°C/min for ibuprofen, 3°C/min for ketoprofen), by replacing the racemate with respective S(+)-enantiomer and by replacing PVP with HEC and MC. Hence, the possible inclusion of enantioselective component within the PVP/drug interaction, responsible for the amorphization of physical mixture over storage, is assumed. Chirality, 2009. © 2008 Wiley-Liss, Inc. 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