Dihydropteroate synthase gene mutations in Pneumocystis and sulfa resistance

Pneumocystis pneumonia (PCP) remains a major cause of illness and death in HIV-infected persons. Sulfa drugs, trimethoprim-sulfamethoxazole (TMP-SMX) and dapsone are mainstays of PCP treatment and prophylaxis. While prophylaxis has reduced the incidence of PCP, its use has raised concerns about development of resistant organisms. The inability to culture human Pneumocystis, Pneumocystis jirovecii, in a standardized culture system prevents routine susceptibility testing and detection of drug resistance. In other microorganisms, sulfa drug resistance has resulted from specific point mutations in the dihydropteroate synthase (DHPS) gene. Similar mutations have been observed in P. jirovecii. Studies have consistently demonstrated a significant association between the use of sulfa drugs for PCP prophylaxis and DHPS gene mutations. Whether these mutations confer resistance to TMP-SMX or dapsone plus trimethoprim for PCP treatment remains unclear. We review studies of DHPS mutations in P. jirovecii and summarize the evidence for resistance to sulfamethoxazole and dapsone

Disordered, stretched, and semiflexible biopolymers in two dimensions

We study the effects of intrinsic sequence-dependent curvature for a two dimensional semiflexible biopolymer with short-range correlation in intrinsic curvatures. We show exactly that when not subjected to any external force, such a system is equivalent to a system with a well-defined intrinsic curvature and a proper renormalized persistence length. We find the exact expression for the distribution function of the equivalent system. However, we show that such an equivalent system does not always exist for the polymer subjected to an external force. We find that under an external force, the effect of sequence-disorder depends upon the averaging order, the degree of disorder, and the experimental conditions, such as the boundary conditions. Furthermore, a short to moderate length biopolymer may be much softer or has a smaller apparent persistent length than what would be expected from the "equivalent system". Moreover, under a strong stretching force and for a long biopolymer, the sequence-disorder is immaterial for elasticity. Finally, the effect of sequence-disorder may depend upon the quantity considered

The UNSW Extrasolar Planet Search: Methods and First Results from a Field Centred on NGC 6633

We report on the current status of the University of New South Wales Extrasolar Planet Search project, giving details of the methods we use to obtain millimagnitude precision photometry using the 0.5m Automated Patrol Telescope. We use a novel observing technique to optimally broaden the PSF and thus largely eliminate photometric noise due to intra-pixel sensitivity variations on the CCD. We have observed 8 crowded Galactic fields using this technique during 2003 and 2004. Our analysis of the first of these fields (centred on the open cluster NGC 6633) has yielded 49 variable stars and 4 shallow transit candidates. Follow-up observations of these candidates have identified them as eclipsing binary systems. We use a detailed simulation of our observations to estimate our sensitivity to short-period planets, and to select a new observing strategy to maximise the number of planets detected.Comment: 16 pages, 9 figures, version published in MNRAS Updated figures, references, and additional discussion in section

Inverse problem for the Landau-Zener effect

We consider the inverse Landau-Zener problem which consists in finding the energy-sweep functions W(t)=E1(t)-E2(t) resulting in the required time dependences of the level populations for a two-level system crossing the resonance one or more times during the sweep. We find sweep functions of particular forms that let manipulate the system in a required way, including complete switching from the state 1 to the state 2 and preparing the system at the exact ground and excited states at resonance.Comment: 7 EPL pages, 6 figure

Adiabatic following criterion, estimation of the nonadiabatic excitation fraction and quantum jumps

An accurate theory describing adiabatic following of the dark, nonabsorbing state in the three-level system is developed. An analytical solution for the wave function of the particle experiencing Raman excitation is found as an expansion in terms of the time varying nonadiabatic perturbation parameter. The solution can be presented as a sum of adiabatic and nonadiabatic parts. Both are estimated quantitatively. It is shown that the limiting value to which the amplitude of the nonadiabatic part tends is equal to the Fourier component of the nonadiabatic perturbation parameter taken at the Rabi frequency of the Raman excitation. The time scale of the variation of both parts is found. While the adiabatic part of the solution varies slowly and follows the change of the nonadiabatic perturbation parameter, the nonadiabatic part appears almost instantly, revealing a jumpwise transition between the dark and bright states. This jump happens when the nonadiabatic perturbation parameter takes its maximum value.Comment: 33 pages, 8 figures, submitted to PRA on 28 Oct. 200

Symmetric eikonal model for projectile-electron excitation and loss in relativistic ion-atom collisions

At impact energies $\stackrel{>}{\sim}1$ GeV/u the projectile-electron excitation and loss occurring in collisions between highly charged ions and neutral atoms is already strongly influenced by the presence of atomic electrons. In order to treat these processes in collisions with heavy atoms we generalize the symmetric eikonal model, used earlier for considerations of electron transitions in ion-atom collisions within the scope of a three-body Coulomb problem. We show that at asymptotically high collision energies this model leads to an exact transition amplitude and is very well suited to describe the projectile-electron excitation and loss at energies above a few GeV/u. In particular, by considering a number of examples we demonstrate advantages of this model over the first Born approximation at impact energies $\sim 1$--30 GeV/u, which are of special interest for atomic physics experiments at the future GSI facilities.Comment: 14 pages, 5 figure

The Internet in New Zealand 2013

Executive Summary The fourth survey of the World Internet Project New Zealand (WIPNZ) was conducted between late July and early September 2013. For the first time, the sample in 2013 used both telephone and internet surveys. This report presents an analysis of the usage of and attitudes to the internet of the resulting sample of 2006 New Zealanders. As internet use approaches saturation in New Zealand, our focus turns from ‘how many people use the internet?’ to ‘how do people use the internet?’ and ‘why do some not use the internet at all?’ To answer these questions, the sample has been divided into five categories: never-users (5% of sample), ex-users (3%), low level users (14%), first generation users (40%) and next generation users (38%). Usage For a large number of people the internet is used daily. Four out of five spend an hour or more online at home every day. Almost everyone under 40 is online, so that only 1% of our under-40 sample are non-users. Accessing the internet ‘on the go’ is prevalent. Seven out of ten users access the internet from a hand-held mobile device such as a smartphone or an iPad. Almost half of the internet users surveyed (48%) said that they had accessed the internet through a tablet, while an even higher proportion (68%) connected through their mobile phone in the past year. Activities Most internet users say they surf or browse the web (96%) or visit social networking sites (81%). 34% of internet users report that they use the cloud, 41% purchase apps and almost two thirds (65%) download free apps. Most users check their email daily (89%). Just over 60% of men aged 30–44 said they have looked at sites with sexual content. Māori and Pasifika internet users, especially those in lower income households, take the lead in subscriptions to music streaming services like Spotify. More than one in five Māori (21%) and Pasifika (23%) users in households with annual incomes of less than $50,000 have paid for a subscription to a music streaming service in the past year. The internet is used as a tool for consumer decision making, with 94% of users looking for information about products online – more than half of users do this at least weekly. For 85% of users, this kind of online research includes comparing prices. Almost half of our users (47%) have logged in to secure areas on Government or Council websites, and 51% have paid taxes, fines or licences online in the past year. Comparing the importance of media Comparing the importance of various forms of media as information sources, 81% of all our respondents rated the internet (including online media such as streamed radio) as important or very important. This was very much higher than the proportion who rated offline media as important: television (47%), radio (37%) and newspapers (37%). One of the most dramatic differences according to age group is the importance of the internet as a source of entertainment and leisure. While watching (offline) television is an important leisure activity for people across all ages, using the internet as a form of entertainment is a young-person phenomenon: 80% of respondents aged 16–29 rate it as important or very important. This 2013 survey has a different sample structure than previous years in order to include New Zealanders without a landline. The questionnaire has also undergone substantial updating to keep pace with changing digital technologies. For these reasons, the present report focuses solely on the findings for 2013, and longitudinal analyses will be presented in a subsequent report next year

Assessing and Manipulating The Illusion of Control of Video Poker Players

The present investigation explored the presence of illusory control in recreation-al video poker players. Using a multi-monitor computer which allowed for two different types of games to be presented concurrently, one on each monitor, players were allowed to freely choose which game they wished to play. One option allowed for the player to select the cards they wished to hold and discard, while the other option was designed such that the computer automatically se-lected the most probabilistically optimal sequence of cards to hold and discard. In the first experiment, two groups of ten participants were exposed to one of two rules (accurate or inaccurate) regarding the chances of winning. No differ-ences in response allocations between the games were found. In the second experiment, thirteen participants were sequentially exposed to a non-rule base-line followed by an inaccurate and subsequently accurate rule. Twelve of the thirteen players preferred the self-selecting game, and following the introduction of an experimenter given rule that was designed to strengthen the illusion (i.e., that the self-selecting option was better), most players increased their preference for this option. However, following the introduction of an experimenter given rule that attempted to weaken the illusion, only about half the participants fol-lowed that rule and reduced playing the self-selecting option. Variability across participants was able to be explained by examining each player’s verbal talk which was emitted overtly throughout the duration of the experiment. Implica-tions for understanding the illusion of control and the verbal behavior of gam-blers are presented