Statistical mechanics of the Cluster-Ising model

We study a Hamiltonian system describing a three-spin-1/2 cluster-like interaction competing with an Ising-like anti-ferromagnetic interaction. We compute free energy, spin correlation functions and entanglement both in the ground and in thermal states. The model undergoes a quantum phase transition between an Ising phase with a nonvanishing magnetization and a cluster phase characterized by a string order. Any two-spin entanglement is found to vanish in both quantum phases because of a nontrivial correlation pattern. Neverthless, the residual multipartite entanglement is maximal in the cluster phase and dependent on the magnetization in the Ising phase. We study the block entropy at the critical point and calculate the central charge of the system, showing that the criticality of the system is beyond the Ising universality class.Comment: To be published in Physical Review

SIR-C/X-SAR data calibration and ground truth campaign over the NASA-CB1 test-site

During the Space Shuttle Endeavour mission in October 1994, a remote-sensing campaign was carried out with the objectives of both radiometric and polarimetric calibration and ground truth data acquisition of bare soils. This paper presents the results obtained in the experiment. Polarimetric cross-talk and channel imbalance values, as well as radiometric calibration parameters, have been found to be within the science requirements for SAR images. Regarding ground truth measurements, a wide spread in the height rms values and correlation lengths has been observed, which has motivated a critical revisiting of surface parameters descriptors

Giving the Green Light to Photochemical Uncaging of Large Biomolecules in High Vacuum

The isolation of biomolecules in a high vacuum enables experiments on fragile species in the absence of a perturbing environment. Since many molecular properties are influenced by local electric fields, here we seek to gain control over the number of charges on a biopolymer by photochemical uncaging. We present the design, modeling, and synthesis of photoactive molecular tags, their labeling to peptides and proteins as well as their photochemical validation in solution and in the gas phase. The tailored tags can be selectively cleaved off at a well-defined time and without the need for any external charge-transferring agents. The energy of a single or two green photons can already trigger the process, and it is soft enough to ensure the integrity of the released biomolecular cargo. We exploit differences in the cleavage pathways in solution and in vacuum and observe a surprising robustness in upscaling the approach from a model system to genuine proteins. The interaction wavelength of 532 nm is compatible with various biomolecular entities, such as oligonucleotides or oligosaccharides.</p

Patients in long-term maintenance therapy for drug use in Italy: analysis of some parameters of social integration and serological status for infectious diseases in a cohort of 1091 patients

BACKGROUND: Heroin addiction often severely disrupts normal social functioning. The aims of this multi-centre study of heroin users in long-term replacement treatment were: i) to provide information on aspects of social condition such as employment, educational background, living status, partner status and any history of drug addiction for partners, comparing these data with that of the general population; ii) to assess the prevalence of hepatitis, syphilis and HIV, because serological status could be a reflection of the social conditions of patients undergoing replacement treatment for drug addiction; iii) to analyse possible relationships between social conditions and serological status. METHODS: A cross-sectional study was carried out in sixteen National Health Service Drug Addiction Units in northern Italy. The data were collected from February 1, 2002 to August 31, 2002. Recruitment eligibility was: maintenance treatment with methadone or buprenorphine, treatment for the previous six months, and at least 18 years of age. In the centres involved in the study no specific criteria or regulations were established concerning the duration of replacement therapy. Participants underwent a face-to-face interview. RESULTS: The conditions of 1091 drug treatment patients were evaluated. The mean duration of drug use was 14.5 years. Duration was shorter in females, in subjects with a higher educational background, and in stable relationships. Most (68%) had completed middle school (11–14 years of age). Seventy-nine percent were employed and 16% were unemployed. Fifty percent lived with their parents, 34% with a partner and 14% alone. Males lived more frequently with their parents (55%), and females more frequently with a partner (60%). Sixty-seven percent of male patients with a stable relationship had a partner who had never used heroin. HCV prevalence was 72%, HBV antibodies were detected in 42% of patients, while 30% had been vaccinated; 12.5% of subjects were HIV positive and 1.5% were positive for TPHA. CONCLUSION: A significant percentage of heroin users in treatment for opiate addiction in the cohort study have characteristics which indicate reasonable integration within broader society. We posit that the combination of effective treatment and a setting of economic prosperity may enhance the social integration of patients with a history of heroin use

Sexual Functioning and Opioid Maintenance Treatment in Women. Results From a Large Multicentre Study

Opioid maintenance treatment (OMT) is the most widespread therapy for both females and males opioid addicts. While many studies have evaluated the OMT impact on men’s sexuality, the data collected about the change in women’s sexual functioning is still limited despite the fact that it is now well-known that opioids - both endogenous and exogenous - affect the endocrine system and play an important role in sexual functioning. The present study aims to determine how OMT with buprenorphine (BUP) or methadone (MTD) affects sexual health in women; examining also any possible emerging correlation between sexual dysfunction (SD), type of opioid and patients’ mental health. This multi-center study case recruited 258 female volunteers attending Italian public Addiction Outpatients Centers that were stabilized with OMT for at least 3 months. SD was assessed with the Arizona Sexual Experience Scale. The twelve-item General Health Questionnaire was used to assess participants’ mental health conditions. The results show that 56.6% of women receiving OMT for at least 3 months presented SD without significant differences between MTD e BUP groups. The majority of the subjects with SD have a poorer quality of intimate relationships and worse mental health than the average. To the best of our knowledge, the present study is the largest report on the presence of SDs in women as a side effects of MTD and BUP used in OMT. Since SDs cause difficulties in intimate relationships, lower patients’ quality of life and interfere with OMT beneficial outcomes, we recommend that women undertaking an opioid therapy have routine screening for SD and we highlight the importance to better examine opioid-endocrine interactions in future studies in order to provide alternative potential treatments such as the choice of opioid, opioid dose reduction and hormone supplementation

Exploring dynamical phase transitions and prethermalization with quantum noise of excitations

Dynamical phase transitions can occur in isolated quantum systems that are brought out of equilibrium by sudden parameter changes. We discuss the characterization of such dynamical phase transitions based on the statistics of produced excitations. We consider both the O(N) model in the large-N limit and a spin model with long-range interactions and show that the dynamical criticality of their prethermal steady states manifests most dramatically not in the average number of excitations but in their higher moments. We argue that the growth of defect fluctuations carries unique signatures of the dynamical criticality, irrespective of the precise details of the model. Our theoretical results should be relevant to quantum quench experiments with ultracold bosonic atoms in optical lattices

Statistical mechanics of the cluster Ising model

We study a Hamiltonian system describing a three-spin-1/2 clusterlike interaction competing with an Ising-like antiferromagnetic interaction. We compute free energy, spin-correlation functions, and entanglement both in the ground and in thermal states. The model undergoes a quantum phase transition between an Ising phase with a nonvanishing magnetization and a cluster phase characterized by a string order. Any two-spin entanglement is found to vanish in both quantum phases because of a nontrivial correlation pattern. Nevertheless, the residual multipartite entanglement is maximal in the cluster phase and dependent on the magnetization in the Ising phase. We study the block entropy at the critical point and calculate the central charge of the system, showing that the criticality of the system is beyond the Ising universality class. © 2011 American Physical Society

TRANSIENT HYPOGAMMAGLOBULINEMIA OF INFANCY: INTRAVENOUS IMMUNOGLOBULIN AS FIRST LINE THERAPY

IVIG (Intravenous immunoglobulin) have significantly improved the prognosis and the quality of life of immunodeficient patients and are routinely used as substitutive therapy. Transient hypogammaglobulinemia of infancy (THI) is a primary humoral immunodeficiency characterized by a transient IgG defect, but is not considered as a disease that justifies substitutive treatment and thus the use of IVIG as an alternative to antibiotic prophylaxis remains controversial also in symptomatic children. We treated 13 THI children severely symptomatic with IVIG (400mg/kg/every 3 weeks) for a limited period (2 or 3 months) and followed them for 1 to 3 years. During the follow-up, the frequency of overall infections decreased approximately tenfold (from 0.39 to 0.047 infection/month per child) and no severe infections were reported. Although this study lacks untreated controls, the results suggest that the observed clinical improvement is correlated to IVIG therapy. Furthermore, our study suggests that the infused IVIG have no long-term effect on endogenous IgG production and do not lengthen the immunodeficiency condition since all children produced a normal amount of specific IgG in response to vaccination carried out 5 months after the end of infusions. In conclusion, our results suggest that IVIG may stop the vicious circle of infection-immunodeficiency and should be considered as a first line therapy in highly symptomatic THI children