University of Texas at Dallas

About: University of Texas at Dallas is a education organization based out in Richardson, Texas, United States. It is known for research contribution in the topics: Population & Computer science. The organization has 14986 authors who have published 35589 publications receiving 1293714 citations. The organization is also known as: UT-Dallas & UT Dallas.

Circular R-Factor Molecules Controlling Penicillinase Synthesis, Replicating in Escherichia coli Under Either Relaxed or Stringent Control

Abstract: Two infectious drug-resistance (R) factors, R28K and R6K, each conferring resistance to a number of penicillins by the synthesis of a penicillinase, were transferred to Proteus mirabilis PM1 and Escherichia coli RC85 host strains. Deoxyribonucleic acid (DNA) extracted from these strains was separated by density-gradient centrifugation and subjected to electron microscopy by use of a modification of the protein-monolayer diffusion technique. Analytical density-gradient centrifugation of the purified DNA from PM1 strains showed, in addition to the major peak at a density of 1.698 g/cm(3) characteristic of Proteus chromosomal DNA, a single satellite band at a density of 1.710 g/cm(3) [guanine plus cytosine (GC) base ratio 50%] for R28K and at 1.704 g/cm(3) (GC base ratio 45%) for R6K. Direct CsCl density-gradient centrifugation of crude lysates of the E. coli (R28K)(+) strain in the presence of ethidium bromide gave rise to a sedimentation profile with a single satellite peak containing covalently closed circular (CCC) DNA molecules with a mean contour length of 21.4 mum [44 x 10(6) atomic mass units (AMU)], although a minority was 13.6 mum in length. From the size of the major class, it was estimated that there were two to three copies of the R28K factor present as CCC molecules per chromosome at various phases of cellular growth. Similar studies of the E. coli (R6K)(+) lysates showed two satellite peaks; peak I contained mostly CCC molecules of contour length 12.8 mum (26 x 10(6) AMU), and peak II, intermediate to peak I and the chromosomal peak, contained CCC molecules of a similar size, together with about equal numbers of catenated molecules, mostly dimers consisting of two interlocked monomers of 12.8 mum. A smaller number (ca. 0.1%) of higher catenanes was also seen. The number of CCC copies of the R6K factor per chromosome present in peak I was calculated as 13 at logarithmic phase and 38 at stationary phase. In peak II, a constant ratio of about one catenated dimer per chromosome was found at all phases of growth. Penicillinase assays of cultures at different phases of growth showed a correlation between the estimated number of R-factor copies present as CCC molecules and the enzyme activity per cell for both R28K and R6K.

Luminosity Determination in pp Collisions at sqrt(s)=7 TeV Using the ATLAS Detector at the LHC

Abstract: Measurements of luminosity obtained using the ATLAS detector during early running of the Large Hadron Collider (LHC) at root s = 7 TeV are presented. The luminosity is independently determined using several detectors and multiple algorithms, each having different acceptances, systematic uncertainties and sensitivity to background. The ratios of the luminosities obtained from these methods are monitored as a function of time and of mu, the average number of inelastic interactions per bunch crossing. Residual time- and mu-dependence between the methods is less than 2% for 0 < mu < 2.5. Absolute luminosity calibrations, performed using beam separation scans, have a common systematic uncertainty of +/- 11%, dominated by the measurement of the LHC beam currents. After calibration, the luminosities obtained from the different methods differ by at most +/- 2%. The visible cross sections measured using the beam scans are compared to predictions obtained with the PYTHIA and PHOJET event generators and the ATLAS detector simulation.

Observation of a Charged Charmoniumlike Structure in e(+)e(-) -> (D* (D)over-bar*)(+/-)pi(-/+) at root s=4.26 GeV

Abstract: We study the process e(+)e(-) -> (D* (D) over bar*)(+/-)pi(-/+) at a center-of-mass energy of 4.26 GeV using a 827 pb(-1) data sample obtained with the BESIII detector at the Beijing Electron Positron Collider. Based on a partial reconstruction technique, the Born cross section is measured to be (137 +/- 9 +/- 15) pb. We observe a structure near the (D* (D) over bar*)(+/-) threshold in the pi(-/+) recoil mass spectrum, which we denote as the Z(c)(+/-) (4025). The measured mass and width of the structure are (4026.3 +/- 2.6 +/- 3.7) MeV/c(2) and (24.8 +/- 5.6 +/- 7.7) MeV, respectively. Its production ratio sigma(e(+)e(-) -> Z(c)(+/-)(4025)pi(-/+)-> (D* (D) over bar*)(+/-)pi(-/+)/sigma(e(+)e(-) -> (D* (D) over bar*)(+/-)pi(-/+) is determined to be 0.65 +/- 0.09 +/- 0.06. The first uncertainties are statistical and the second are systematic.

The Signaling Effect of Corporate Social Responsibility in Emerging Economies

Abstract: What signals do firms in emerging economies send to stakeholders when they adopt corporate social responsibility (CSR) practices? We argue that in emerging economies, firms that adopt CSR practices positively signal investors that their firms have superior capabilities for filling institutional voids. From an institution-based view, we hypothesize that the institutional environment moderates the signaling effect of CSR on a firm’s financial performance. Based on a sample of firms from ten Asian emerging economies, we find a positive relationship between CSR practices and financial performance. This positive relationship is stronger in the less developed capital market than in the more developed one. The financial benefits of CSR practices are also more salient in the low information diffusion market than in the high one. We emphasize that signaling theory and the institution-based view can jointly contribute to the CSR literature.

Risk and Return Revisited

Abstract: 0 ne time-honored rule in the field of finance is that risk and return are related. Often called the “no free lunch” principle, it asserts that over the long run it is not possible to achieve exceptional returns without accepting substantial risk. Any standard equilibrium model of asset pricing justifies ths relationship. Data from Ibbotson Associates confirm that since 1926, U.S. common stocks have provided a total return of 10.7% per year, about seven percentage points greater than the return from riskless Treasury bds.