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Log M (log + m)

Distribution by Scientific Domains

Medical Sciences	37%
Mathematics and Statistics	37%

Selected Abstracts

Impaired EDHF-Mediated Relaxation in Porcine Pulmonary Micro-Arteries by Cold Storage with University of Wisconsin and Euro-Collins Solutions

JOURNAL OF CARDIAC SURGERY, Issue 6 2002
Wei Zou
Background: Vascular endothelium plays a key role in regulation of vascular tone. Hyperkalemia has been demonstrated to impair the EDHF-mediated endothelial function in coronary circulation. University of Wisconsin (UW) and Eruo-collins (EC) solutions are used for organ preservation in transplantation surgery. The potassium concentration in UW or EC solutions is as high as 125 mmol/L or 115 mmol/L, respectively. This study was designed to examine whether hyperkalemia or storage with UW and EC solutions affects the relaxation mediated by EDHF in the porcine pulmonary micro-arteries. Methods: Porcine pulmonary micro-artery rings (diameter 200,450 ,m) were studied in myograph (n = 8 in each group). After incubation with hyperkalemia (K+ 125 mmol/L, at 37° C), UW or EC solutions (at 4° C for 4 hours), EDHF-mediated relaxation induced by bradykinin (BK, ,10 to ,6.5 log M) in the presence of inhibitors for cyclooxygenase (Indomethacin, 7 ,M), nitric oxide synthase (NG -nitro- L -arginine, 300 ,M), and oxyhemoglobin (20 ,M) was compared with control (Krebs' solution) in precontraction with U46619 (,7.5 log M). Results: The EDHF-mediated relaxation to BK was 69.6 ± 6.3% compared with 97.1 ± 1.7% (p= 0.003) in control (no inhibitors). After incubation with hyperkalemia, the relaxation significantly decreased (38.6 ± 3.0% vs. 59.1 ± 7.4%, p= 0.03). Storage with UW or EC solutions also significantly decreased the relaxation (49.3 ± 7.3% vs. 65.2 ± 3.5%, p= 0.04 and 51.9 ± 8.4% vs. 60.3 ± 6.1%, p= 0.02, respectively). Conclusions: In porcine pulmonary micro-arteries, exposure to hyperkalemia or storage with UW or EC solutions at 4°C for 4 hours impairs the EDHF-mediated endothelial function. The clinical significance of this effect should be further studied. [source]

Satellite kinematics , II.

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2009
The halo mass, luminosity relation of central galaxies in SDSS
ABSTRACT The kinematics of satellite galaxies reflect the masses of the extended dark matter haloes in which they orbit, and thus shed light on the mass,luminosity relation (MLR) of their corresponding central galaxies. In this paper, we select a large sample of centrals and satellites from the Sloan Digital Sky Survey and measure the kinematics (velocity dispersions) of the satellite galaxies as a function of the r -band luminosity of the central galaxies. Using the analytical framework presented in More, van den Bosch & Cacciato, we use these data to infer both the mean and the scatter of the MLR of central galaxies, carefully taking account of selection effects and biases introduced by the stacking procedure. As expected, brighter centrals on average reside in more massive haloes. In addition, we find that the scatter in halo masses for centrals of a given luminosity, ,log M, also increases with increasing luminosity. As we demonstrate, this is consistent with ,log L, which reflects the scatter in the conditional probability function P(Lc|M), being independent of halo mass. Our analysis of the satellite kinematics yields ,log L= 0.16 ± 0.04, in excellent agreement with constraints from clustering and group catalogues, and with predictions from a semi-analytical model of galaxy formation. We thus conclude that the amount of stochasticity in galaxy formation, which is characterized by ,log L, is well constrained, independent of halo mass and in a good agreement with current models of galaxy formation. [source]

Spectroscopic and photometric observations of the selected Algol-type binaries , II.

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2008
V2080 Cygni, V2365 Ophiuchi
ABSTRACT This paper is the second in the planned series of investigations. We present new radial velocities and photometric observations of V2080 Cyg and V2365 Oph. New UBV photometric data and radial velocities were analysed for the systems' parameters. While V2080 Cyg consists of two nearly equal F-type main-sequence stars, V2365 Oph has two different components, namely an early A-type primary and a G-type secondary star. New ephemerides are calculated for both systems. The masses of the component stars have been derived as 1.19 ± 0.02 and 1.16 ± 0.02 M, for V2080 Cyg and 1.97 ± 0.02 and 1.06 ± 0.01 M, for V2365 Oph. The effective temperatures and reddening of the systems have been estimated from Johnson wide-band UBV photometric calibrations. The radii have been measured by simultaneous fitting the UBV light curves using Wilson,Devinney code and are 1.60 ± 0.01 R, for both components of V2080 Cyg and 2.19 ± 0.01 and 0.934 ± 0.004 R, for V2365 Oph. The absolute parameters of the stars in both systems lie within the same ranges in the mass,radius, mass,effective temperature, mass,luminosity and luminosity,effective temperature planes as in detached Algol systems. A comparison between the properties of the systems of interest and the predictions of theoretical evolutionary models is undertaken in the log g,logTeff, log R, log M and radius,log age diagrams. The model predictions match the measured properties of V2080 Cyg for an age of about 5.6 Gyr and a ,solar' metal abundance (Z= 0.019), indicating the components near the end of their core hydrogen-burning phases. However, the position of the components of V2365 Oph on the Hertzsprung,Russell (HR) diagram is best reproduced with evolutionary models for somewhat metal-deficient (Z= 0.004) stars. We found an age of about 700 Myr, with the primary component slightly evolved off the zero-age main-sequence and the secondary one still very close to it. From the basic stellar parameters we have also redetermined the distances to V2080 Cyg and V2365 Oph as 78 ± 1 and 251 ± 8 pc, which are in agreement with, and more accurate than, Hipparcos values. The observations show that at least one of the components of V2365 Oph is an intrinsic variable with a period and peak-to-peak amplitude of 0.07 d and 0.05 mag, respectively. In accordance with its position in the HR diagram, the primary component should be considered as a , Scuti star and it is believed to be the variable star in the system. [source]

Effects of potassium channel opener KRN4884 on human conduit arteries used as coronary bypass grafts

BRITISH JOURNAL OF CLINICAL PHARMACOLOGY, Issue 2 2000
Zhen Ren
Aims The effects of a new potassium channel opener KRN4884 on human arteries have not been studied. This study was designed to investigate the effects of KRN4884 on the human internal mammary artery (IMA) in order to provide information on possible clinical applications of KRN4884 for preventing and relieving vasospasm of arterial grafts in coronary artery bypass grafting. Methods IMA segments (n = 140) taken from patients undergoing coronary surgery were studied in the organ chamber. Concentration-relaxation curves for KRN4884 were established in the IMA precontracted with noradrenaline (NA), 5-hydroxytryptamine (5-HT), angiotensin II (ANG II), and endothelin-1 (ET-1). The effect of glibenclamide (GBC) on the KRN4884-induced relaxation was also examined in NA or 5-HT-precontracted IMA. Concentration-contraction curves for the four vasoconstrictors were constructed without/with pretreatment of KNR4884 (1 or 30 µm) for 15 min. Results KRN4884 induced less relaxation (P < 0.05) in the precontraction induced by ET-1 (72.9 ± 5.5%) than by ANG II (94.2 ± 3.2%) or NA (93.7 ± 4.1%) with lower EC50 (P < 0.05) for ANG II (,8.54 ± 0.54 log m) than that for NA (,6.14 ± 0.15 log M) or ET-1 (,6.69 ± 0.34 log m). The relaxation in the IMA pretreated with GBC was less than that in control (P < 0.05). KRN4884-pretreatment significantly reduced the contraction (P < 0.05) induced by NA (151.3 ± 18.4% vs 82.7 ± 8.7%), 5-HT (82.7 ± 12.2% vs 30.1 ± 7.3%), and ANG II (24.3 ± 6.3% vs 5.4 ± 1.6%), but did not significantly reduce the contraction induced by ET-1 (P > 0.05). Conclusion KRN4884 has marked vasorelaxant effects on the human IMA contracted by a variety of vasoconstrictors and the effect is vasoconstrictor-selective. [source]

The two-median problem on Manhattan meshes

NETWORKS: AN INTERNATIONAL JOURNAL, Issue 3 2007
Mordecai J. Golin
Abstract We investigate the two-median problem on a mesh with M columns and N rows (M , N), under the Manhattan (L1) metric. We derive exact algorithms with respect to m, n, and r, the number of columns, rows, and vertices, respectively, that contain requests. Specifically, we give an O(mn2 log m) time, O(r) space algorithm for general (nonuniform) meshes (assuming m , n). For uniform meshes, we give two algorithms both using O(MN) space. One is an O(MN2) time algorithm, while the other is an algorithm running in O(MN log N) time with high probability and in O(MN2) time in the worst case assuming the weights are independent and identically distributed random variables satisfying certain natural conditions. These improve upon the previously best-known algorithm that runs in O(mn2r) time. © 2007 Wiley Periodicals, Inc. NETWORKS, Vol. 49(3), 226,233 2007 [source]

Phase transition for Parking blocks, Brownian excursion and coalescence

RANDOM STRUCTURES AND ALGORITHMS, Issue 1 2002
P. Chassaing
Abstract In this paper, we consider hashing with linear probing for a hashing table with m places, n items (n < m), and , = m , n empty places. For a noncomputer science-minded reader, we shall use the metaphore of n cars parking on m places: each car ci chooses a place pi at random, and if pi is occupied, ci tries successively pi + 1, pi + 2, until it finds an empty place. Pittel [42] proves that when ,/m goes to some positive limit , < 1, the size B of the largest block of consecutive cars satisfies 2(, , 1 , log ,)B = 2 log m , 3 log log m + ,m, where ,m converges weakly to an extreme-value distribution. In this paper we examine at which level for n a phase transition occurs between B = o(m) and m , B = o(m). The intermediate case reveals an interesting behavior of sizes of blocks, related to the standard additive coalescent in the same way as the sizes of connected components of the random graph are related to the multiplicative coalescent. © 2002 Wiley Periodicals, Inc. Random Struct. Alg., 21: 76,119, 2002 [source]