225 research outputs found
Erratum: Fluctuation relations for systems in a constant magnetic field (Physical Review E (2020) 102 (030101R) DOI: 10.1103/PhysRevE.102.030101)
Erratum. After the publication of this paper, we found an inconsequential mistake in the derivation of the dissipation function for the Nosé-Hoover thermostatted system, Eq. (17) of the original paper. A complete and correct derivation for O(0)(X) is now reported in Appendix B of Ref. [1], where, in particular, it is shown that (Formula Presented) (Figure Presented)
Fluctuation relations for systems in a constant magnetic field
The validity of the fluctuation relations (FRs) for systems in a constant magnetic field is investigated. Recently introduced time-reversal symmetries that hold in the presence of static electric and magnetic fields and of deterministic thermostats are used to prove the transient FRs without invoking, as commonly done, inversion of the magnetic field. Steady-state FRs are also derived, under the t-mixing condition. These results extend the predictive power of important statistical mechanics relations. We illustrate this via the nonlinear response for the cumulants of the dissipation, showing how the alternative FRs enable one to determine analytically null cumulants also for systems in a single magnetic field
Fluctuation relations for dissipative systems in constant external magnetic field: Theory and molecular dynamics simulations
We illustrate how, contrary to common belief, transient Fluctuation Relations (FRs) for systems in constant external magnetic field hold without the inversion of the field. Building on previous work providing generalized time-reversal symmetries for systems in parallel external magnetic and electric fields, we observe that the standard proof of these important nonequilibrium properties can be fully reinstated in the presence of net dissipation. This generalizes recent results for the FRs in orthogonal fields-an interesting but less commonly investigated geometry-and enables direct comparison with existing literature. We also present for the first time a numerical demonstration of the validity of the transient FRs with nonzero magnetic field via nonequilibrium molecular dynamics simulations of a realistic model of liquid NaCl
Non-malleable codes for space-bounded tampering
Non-malleable codes—introduced by Dziembowski, Pietrzak and Wichs at ICS 2010—are key-less coding schemes in which mauling attempts to an encoding of a given message, w.r.t. some class of tampering adversaries, result in a decoded value that is either identical or unrelated to the original message. Such codes are very useful for protecting arbitrary cryptographic primitives against tampering attacks against the memory. Clearly, non-malleability is hopeless if the class of tampering adversaries includes the decoding and encoding algorithm. To circumvent this obstacle, the majority of past research focused on designing non-malleable codes for various tampering classes, albeit assuming that the adversary is unable to decode. Nonetheless, in many concrete settings, this assumption is not realistic
Research Note: Cecal microbiota harbored by free-range chickens may influence the reduction of Helicobacter pullorum relative abundance
Helicobacter pullorum is recognized as an emerging food-borne pathogen that may colonize the intestinal tract and the liver of avian species and humans causing several gastrointestinal and liver diseases. However, not all strains are reported to be capable of causing clinical disease, thus making poultry as reservoir for the zoonotic transmission of the infection through carcass contamination of broilers at slaughter. In poultry, the prevalence of this bacterium could be underestimated and the available data mainly refer to conventional rearing systems, whereas free-range and organic breedings have been poorly investigated. Therefore, this study was aimed to characterize the caecal microbiota community of free-range grown chickens and determine the presence and the relative abundance of H. pullorum by using NGS-based 16S rDNA sequencing. A total of 18 chickens reared for 56 d on a semi-extensive management system were euthanized at two time points: 9 birds at 28 d of age (before have access to outdoor; IÂ =Â Indoor) and other 9 birds at 56 d of age (before slaughter; OÂ =Â Outdoor). Cecal contents were collected for microbiota analyses. H. pullorum was detected in the cecum of 16/18 samples and its proportion in indoor was significantly higher than outdoor chickens (2.46 and 0.52%, respectively; P < 0.05), showing 78.8% of decrease with the outdoor access of the chickens. Therefore, it may be assumed that the potential for zoonotic infection is less likely. Moreover, H. pullorum was negatively correlated with 17 bacterial species as significantly more abundant in Outdoor microbial caecal communities. Among these, we highlighted the presence of Mucispirillium schaedleri and Oscillospira, already previously associated with a healthy gut and thus representing promising gut bacterial markers for host health. Our findings suggest that alternative production systems with outdoor access, may play a crucial role in the establishment of a healthy gut microbiota, which in turn might prevent colonization of harmful bacteria such as Helicobacter pullorum
Time-Space Tradeoffs and Short Collisions in Merkle-DamgĂĄrd Hash Functions
We study collision-finding against Merkle-DamgĂĄrd hashing in the random-oracle model by adversaries with an arbitrary -bit auxiliary advice input about the random oracle and queries. Recent work showed that such adversaries can find collisions (with respect to a random IV) with advantage , where is the output length, beating the birthday bound by a factor of . These attacks were shown to be optimal.
We observe that the collisions produced are very long, on the order blocks, which would limit their practical relevance. We prove several results related to improving these attacks to find short collisions. We first exhibit a simple attack for finding -block-long collisions achieving advantage . We then study if this attack is optimal. We show that the prior technique based on the bit-fixing model (used for the bound) provably cannot reach this bound, and towards a general result we prove there are qualitative jumps in the optimal attacks for finding length , length , and unbounded-length collisions. Namely, the optimal attacks achieve (up to logarithmic factors) order of , and advantage. We also give an upper bound on the advantage of a restricted class of short-collision finding attacks via a new analysis on the growth of trees in random functional graphs that may be of independent interest
Peripheral blood mono-nuclear cells implantation in patients with Peripheral Arterial Disease: a pilot study for clinical and biochemical outcome of neoangiogenesis.
BACKGROUND: Substantial progresses in the management of peripheral arterial disease (PAD) have been made in the past two decades. Progress in the understanding of the endothelial-platelet interaction during health and disease state has resulted in better antiplatelet drugs that can prevent platelet aggregation, activation and thrombosis during angioplasty and stenting. A role in physiological and pathological angiogenesis in adults has been recently shown in bone marrow–derived circulating endothelial progenitors (BM-DCEPs) identified in the peripheral blood. These findings have paved the way for the development of therapeutic neovascularization techniques using endothelial progenitors. METHODS: This pilot study includes five patients, aged 60 to 75, with a history of claudication and recruited from September 2010 to February 2011 at the A.O.U. Federico II of Naples. PBMNCs have been implanted three times in the limb with the worst ABI value in all the patients included in the study. The clinical follow up was performed during the subsequent 12 months from the beginning of the treatment. RESULTS: In four patients there was a regression of ulcerative lesions. One patient’s condition improved after the first implantation but later did not respond to the further treatments. All patients achieved a pain relief as judged by the numeric pain scale. Pain relief remained satisfactory in three patients for one year. Pain gradually returned to the pre-treatment level in two patients. All patients referred an ameliorating in their quality of life expressed even by an improvement in claudication free walking distance. These improvements are reflected also by intra-arterial digital subtraction angiography (IADSA) that shows an improvement of arterial vascularization. CONCLUSIONS: The data from this study suggest an efficacy of BM-DCEPs implantation in terms of improvement of the vascularization and quality of life in patients affected by Peripheral Arterial Disease. Nevertheless a double-blind placebo-controlled study is needed to confirm our findings
Feasibility of inguinal hernioplasty under local anaesthesia in elderly patients.
BACKGROUND: The aim of this study is to evaluate the feasibility and the safety of hernioplasty under local anaesthesia in elderly patients with significant comorbidity. METHODS: A total of 218 patients underwent inguinal hernia repair with mesh between June 2009 and July 2012. Presence of comorbid conditions and complications were compared between patients younger and older than 70 years. RESULTS: Hernia repair in older patients were more likely associated with comorbid conditions than in their younger counterparts ( hypertension: 25% vs 8.16%; cardiovascular diseases: 50% vs 22%; benign prostatic hypertrophy 60% vs 30%). The most common postoperative complications in both groups were recurrence, wound infection, urinary retention. There was a slightly higher rate of complication in elderly group. CONCLUSIONS: Inguinal hernia repair with local anaesthesia is quite safe and results in a good success rate in elderly patients despite a higher rate of comorbidity typical of this kind of patient
Increased use of high-flow nasal cannulas after the pandemic in bronchiolitis: a more severe disease or a changed physician’s attitude?
After the SARS-CoV-2 pandemic, we noticed a marked increase in high-flow nasal cannula use for bronchiolitis. This study aims to report the percentage of children treated with high-flow nasal cannula (HFNC) in various seasons. The secondary outcomes were admissions for bronchiolitis, virological results, hospital burden, and NICU/PICU need. We conducted a retrospective study in four Italian hospitals, examining the medical records of all infants (< 12 months) hospitalized for bronchiolitis in the last four winter seasons (1 September–31 March 2018–2022). In the 2021–2022 winter season, 66% of admitted children received HFNC versus 23%, 38%, and 35% in the previous 3 years. A total of 876 patients were hospitalized in the study periods. In 2021–2022, 300 infants were hospitalized for bronchiolitis, 22 in 2020–2021, 259 in 2019–2020, and 295 in 2018–2019. The percentage of patients needing intensive care varied from 28.7% to 18%, 22%, and 15% in each of the four considered periods (p < 0.05). Seventy-seven percent of children received oxygen in the 2021–2022 winter; vs 50%, 63%, and 55% (p < 0.01) in the previous 3 years. NIV/CPAP was used in 23%, 9%, 16%, and 12%, respectively. In 2021–2020, 2% of patients were intubated; 0 in 2020–2021, 3% in 2019–2020, and 1% in 2018–2019. Conclusion: This study shows a marked increase in respiratory support and intensive care admissions this last winter. While these severity indexes were all driven by medical choices, more reliable indexes such as intubation rate and length of stay did not change. Therefore, we suggest that there is a more aggressive treatment attitude rather than a more severe disease.What is Known:• COVID-19 pandemic deeply impacted bronchiolitis epidemiology, reducing hospitalizations to onetenth. In the 2021-2022 winter, bronchiolitis resurged to pre-pandemic numbers in Europe.What is New:• Bronchiolitis hospitalization rose much faster in the 2021-2022 winter period, peaking at a higher level. Respiratory supports and high-flow nasal cannula increased significantly compared to the pre-pandemic era
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