Mean field model for spatially extended systems in the presence of multiplicative noise

We present a mean field model that describes the effect of multiplicative noise in spatially extended systems. The model can be solved analytically. For the case of the phi4 potential it predicts that the phase transition is shifted. This conclusion is supported by numerical simulations of this model in two dimensions.

Statistical mechanics in the extended Gaussian ensemble

The extended Gaussian ensemble (EGE) is introduced as a generalization of the canonical ensemble. This ensemble is a further extension of the Gaussian ensemble introduced by Hetherington [J. Low Temp. Phys. 66, 145 (1987)]. The statistical mechanical formalism is derived both from the analysis of the system attached to a finite reservoir and from the maximum statistical entropy principle. The probability of each microstate depends on two parameters ß and ¿ which allow one to fix, independently, the mean energy of the system and the energy fluctuations, respectively. We establish the Legendre transform structure for the generalized thermodynamic potential and propose a stability criterion. We also compare the EGE probability distribution with the q-exponential distribution. As an example, an application to a system with few independent spins is presented.

Colored noise in spatially extended systems

We study the effects of time and space correlations of an external additive colored noise on the steady-state behavior of a time-dependent Ginzburg-Landau model. Simulations show the existence of nonequilibrium phase transitions controlled by both the correlation time and length of the noise. A Fokker-Planck equation and the steady probability density of the process are obtained by means of a theoretical approximation.

Access Update, February 2012

Monthly newsletter for the Iowa Department of Public Health

Alpha-band suppression in the visual word form area as a functional bottleneck to consciousness.

The current state of empirical investigations refers to consciousness as an all-or-none phenomenon. However, a recent theoretical account opens up this perspective by proposing a partial level (between nil and full) of conscious perception. In the well-studied case of single-word reading, short-lived exposure can trigger incomplete word-form recognition wherein letters fall short of forming a whole word in one's conscious perception thereby hindering word-meaning access and report. Hence, the processing from incomplete to complete word-form recognition straightforwardly mirrors a transition from partial to full-blown consciousness. We therefore hypothesized that this putative functional bottleneck to consciousness (i.e. the perceptual boundary between partial and full conscious perception) would emerge at a major key hub region for word-form recognition during reading, namely the left occipito-temporal junction. We applied a real-time staircase procedure and titrated subjective reports at the threshold between partial (letters) and full (whole word) conscious perception. This experimental approach allowed us to collect trials with identical physical stimulation, yet reflecting distinct perceptual experience levels. Oscillatory brain activity was monitored with magnetoencephalography and revealed that the transition from partial-to-full word-form perception was accompanied by alpha-band (7-11 Hz) power suppression in the posterior left occipito-temporal cortex. This modulation of rhythmic activity extended anteriorly towards the visual word form area (VWFA), a region whose selectivity for word-forms in perception is highly debated. The current findings provide electrophysiological evidence for a functional bottleneck to consciousness thereby empirically instantiating a recently proposed partial perspective on consciousness. Moreover, the findings provide an entirely new outlook on the functioning of the VWFA as a late bottleneck to full-blown conscious word-form perception.

Design of Optical Systems With Extended Depth of Field: an Educational Approach to Wavefront Coding Techniques

A practical activity designed to introduce wavefront coding techniques as a method to extend the depth of field in optical systems is presented. The activity is suitable for advanced undergraduate students since it combines different topics in optical engineering such as optical system design, aberration theory, Fourier optics, and digital image processing. This paper provides the theoretical background and technical information for performing the experiment. The proposed activity requires students able to develop a wide range of skills since they are expected to deal with optical components, including spatial light modulators, and develop scripts to perform some calculations.

Evidence of extended orientational order in amorphous Fe/Sm thin films

Amorphous thin films of Fe/Sm, prepared by evaporation methods, have been magnetically characterized and the results were interpreted in terms of the random magnets theory. The samples behave as 2D and 3D random magnets depending on the total thickness of the film. From our data the existence of orientational order, which greatly influences the magnetic behavior of the films, is also clear.

Pharmacokinetic variability of extended interval tobramycin in burn patients.

BACKGROUND: Aminoglycosides are mandatory in the treatment of severe infections in burns. However, their pharmacokinetics are difficult to predict in critically ill patients. Our objective was to describe the pharmacokinetic parameters of high doses of tobramycin administered at extended intervals in severely burned patients. METHODS: We prospectively enrolled 23 burned patients receiving tobramycin in combination therapy for Pseudomonas species infections in a burn ICU over 2 years in a therapeutic drug monitoring program. Trough and post peak tobramycin levels were measured to adjust drug dosage. Pharmacokinetic parameters were derived from two points first order kinetics. RESULTS: Tobramycin peak concentration was 7.4 (3.1-19.6)microg/ml and Cmax/MIC ratio 14.8 (2.8-39.2). Half-life was 6.9 (range 1.8-24.6)h with a distribution volume of 0.4 (0.2-1.0)l/kg. Clearance was 35 (14-121)ml/min and was weakly but significantly correlated with creatinine clearance. CONCLUSION: Tobramycin had a normal clearance, but an increased volume of distribution and a prolonged half-life in burned patients. However, the pharmacokinetic parameters of tobramycin are highly variable in burned patients. These data support extended interval administration and strongly suggest that aminoglycosides should only be used within a structured pharmacokinetic monitoring program.

Les règles n'ont plus la cote: une question de contraception ou de choix [To bleed or not--a new dogma or a real choice in contraception?]

On en parle ! Il est question de la suppression des règles par l'administration de contraceptifs oestro-progestatifs (pilule, patch ou anneau vaginal) en cycles longs (cycles prolongés ; cycles étendus ; extended cycles) entraînant des périodes d'aménorrhée, rythmées par des intervalles libres de sept jours sans administration hormonale. L'indication à ce mode de prescription est presque unanimement reconnue pour le traitement des pathologies bénéficiant de la suppression des règles et des fluctuations hormonales inhérentes à l'activité ovarienne. Ce traitement suscite cependant également de l'intérêt pour une indication du type mode de vie. Les modalités thérapeutiques, les avantages et inconvénients sont examinés à la lumière de l'attente des femmes et de leur droit au choix éclairé et libre. Let's talk about it ! Suppression of menstruation, by extending the duration of contraceptives containing estro-progestins (oral contraception, patch or vaginal ring) to long cycles, is a new approach in the field of contraception. These extended cycles aim at obtaining prolonged amenorrhea, interrupted periodically by a free interval of 7 days without hormone intake and thus causing breakthrough bleeding. Pathologies, which are supposed to get some benefit from the suppression of menstruation and of hormone level variations related to ovarian activity, are widely recognized as an indication. Some interest is also coming up for so called life style indications. Treatment issues, advantages and disadvantages are examined in the light of women's expectations and right to access to informed consent and independent choice.

Access Update, April 2012

Monthly newsletter for the Iowa Department of Public Health

Extended treatment of treatment-naive patients with chronic hepatitis c virus (HCV) genotype 1-infection and slow response to pegylated interferon-alfa and ribavirin: a meta-analysis

Aims: Recently, several clinical trials analyzed if extended duration of treatment with pegylated interferon-alfa and ribavirin over 48 weeks can improve sustained virologic response (SVR) rates in HCV genotype 1-infected patients with slow virologic response. Because results of these clinical trials are conflicting, we performed a metaanalysis to determine the overall impact of extended treatment compared to standard treatment on virologic response rates in treatment-naive HCV genotype 1 slow responders. Methods: Literature search was performed independently by two observers using Pub Med, EMBASE, CENTRAL and abstracts presented in English at international liver and gastroenterology meetings. Randomized controlled clinical trials (RCTs; but studies that re-analyzed data retrospectively RCTs were also allowed) were considered if they included monoinfected treatment-naive HCV genotype 1 patients and compared treatment with pegIFN-alfa 2a or 2b in combination with ribavirin for 48 weeks versus extended treatment (up to 72 weeks) in slow responders. Primary and secondary end points were SVR rates and end-of-treatment (EOT) and relapse rates, respectively. In the present meta-analysis, study endpoints were summarized with a DerSimonian-Laird estimate for binary outcome basing on a random effects model. Results: Literature search yielded seven RTCs addressing the benefit of extended treatment with pegylated interferon-alfa and ribavirin in treatment-naive HCV genotype 1 slow responders. In total, 1330 slow responders were included in our meta-analysis. We show that extended treatment duration compared to the standard of care significantly improves SVR rates in HCV genotype 1 slow responders (12.4% improvement of overall SVR rate, 95% CI 0.055- 0.193, P = 0.0005). In addition, we show that rates of viral relapse were significantly reduced by extended treatment (24.1% reduction of relapse, 95% CI −0.3332 to −0.1487, P < 0.0001), whereas no significant impact of extended treatment on EOT response rates was found. Though extended treatment was burdened with an enhanced rate of premature treatment discontinuation due to interferonalfa- and ribavirin-related side effects, the frequency of serious adverse events was not increased. Conclusions: Treatment extension in HCV genotype 1 slow responders can improve SVR rates in difficult to treat patients and should be considered in patients who need to be treated before specific antivirals will be approved.

Insight into oversight : how information commissioners contribute to the achievement of access-to-information policy objectives

This thesis examines how oversight bodies, as part of an ATI policy, contribute to the achievement of the policy's objectives. The aim of the thesis is to see how oversight bodies and the work they do affects the implementation of their respective ATI policies and thereby contributes to the objectives of those policies using a comparative case study approach. The thesis investigates how federal/central government level information commissioners in four jurisdictions - Germany, India, Scotland, and Switzerland - enforce their respective ATI policies, which tasks they carry out in addition to their enforcement duties, the challenges they face in their work and the ways they overcome these. Qualitative data were gathered from primary and secondary documents as well as in 37 semi-structured interviews with staff of the commissioners' offices, administrative officials whose job entails complying with ATI, people who have made ATI requests and appealed to their respective oversight body, and external experts who have studied ATI implementation in their particular jurisdiction. The thesis finds that while the aspect of an oversight body's formal independence that has the greatest impact on its work is resource control and that although the powers granted by law set the framework for ensuring that the administration is properly complying with the policy, the commissioner's leadership style - a component of informal independence - has more influence than formal attributes of independence in setting out how resources are obtained and used as well as how staff set priorities and utilize the powers they are granted by law. The conclusion, therefore, is that an ATI oversight body's ability to contribute to the achievement of the policy's objectives is a function of three main factors: a. commissioner's leadership style; b. adequacy of resources and degree of control the organization has over them; c. powers and the exercise of discretion in using them. In effect, the thesis argues that it is difficult to pinpoint the value of the formal powers set out for the oversight body in the ATI law, and that their decisions on whether and how to use them are more important than the presumed strength of the powers. It also claims that the choices made by the commissioners and their staff regarding priorities and use of powers are determined to a large extent by the adequacy of resources and the degree of control the organization has over those resources. In turn, how the head of the organization leads and manages the oversight body is crucial to both the adequacy of the organization's resources and the decisions made about the use of powers. Together, these three factors have a significant impact on the body's effectiveness in contributing to ATI objectives.

Homicide-suicide cases in Switzerland and their impact on the Swiss Weapon Law.

Homicide followed by the suicide of the offender is a well-known phenomenon. In most cases, it takes place in the context of the so-called "family tragedies." A recent series of such family tragedies in Switzerland prompted an intensive debate in the media and the Swiss government concerning the Swiss Weapon Law, in particular the requirement to keep personal army weapons at home. The present study of Homicide-Suicide cases in Switzerland, thus focuses on the role played by guns, especially military weapons, in such crimes. We investigated retrospectively 75 cases of Homicide-Suicide, comprising 172 individuals and spanning a period of 23 years in western and central Switzerland. Our results show that if guns were used in 76% of the cases, army weapons were the cause of death in 25% of the total. In 28% of the deaths caused by a gunshot, the exact type of the gun and its origin could not be determined. Thus, the majority of Homicide-Suicide cases in Switzerland involve the use of guns. The exact percentage of cases were military weapons were involved could not be defined. In our opinion, a stricter weapons law, restricting access to firearms, would be a factor of prevention of Homicide- Suicide cases in Switzerland.

Access Update, June 2012

Monthly newsletter for the Iowa Department of Public Health