Tag: pubmed

Phys Rev Lett. 2021 Dec 10;127(24):240603. doi: 10.1103/PhysRevLett.127.240603.

ABSTRACT

Identifying the relevant degrees of freedom in a complex physical system is a key stage in developing effective theories in and out of equilibrium. The celebrated renormalization group provides a framework for this, but its practical execution in unfamiliar systems is fraught with ad hoc choices, whereas machine learning approaches, though promising, lack formal interpretability. Here we present an algorithm employing state-of-the-art results in machine-learning-based estimation of information-theoretic quantities, overcoming these challenges, and use this advance to develop a new paradigm in identifying the most relevant operators describing properties of the system. We demonstrate this on an interacting model, where the emergent degrees of freedom are qualitatively different from the microscopic constituents. Our results push the boundary of formally interpretable applications of machine learning, conceptually paving the way toward automated theory building.

PMID:34951810 | DOI:10.1103/PhysRevLett.127.240603

Phys Rev Lett. 2021 Dec 10;127(24):241102. doi: 10.1103/PhysRevLett.127.241102.

ABSTRACT

High-quality optical resonant cavities require low optical loss, typically on the scale of parts per million. However, unintended micron-scale contaminants on the resonator mirrors that absorb the light circulating in the cavity can deform the surface thermoelastically and thus increase losses by scattering light out of the resonant mode. The point absorber effect is a limiting factor in some high-power cavity experiments, for example, the Advanced LIGO gravitational-wave detector. In this Letter, we present a general approach to the point absorber effect from first principles and simulate its contribution to the increased scattering. The achievable circulating power in current and future gravitational-wave detectors is calculated statistically given different point absorber configurations. Our formulation is further confirmed experimentally in comparison with the scattered power in the arm cavity of Advanced LIGO measured by in situ photodiodes. The understanding presented here provides an important tool in the global effort to design future gravitational-wave detectors that support high optical power and thus reduce quantum noise.

PMID:34951783 | DOI:10.1103/PhysRevLett.127.241102

Phys Rev Lett. 2021 Dec 10;127(24):242002. doi: 10.1103/PhysRevLett.127.242002.

ABSTRACT

We present an analysis of the pion-nucleon σ-term σ_{πN} using six ensembles with 2+1+1-flavor highly improved staggered quark action generated by the MILC Collaboration. The most serious systematic effect in lattice calculations of nucleon correlation functions is the contribution of excited states. We estimate these using chiral perturbation theory (χPT) and show that the leading contribution to the isoscalar scalar charge comes from Nπ and Nππ states. Therefore, we carry out two analyses of lattice data to remove excited-state contamination, the standard one and a new one including Nπ and Nππ states. We find that the standard analysis gives σ_{πN}=41.9(4.9) MeV, consistent with previous lattice calculations, while our preferred χPT-motivated analysis gives σ_{πN}=59.6(7.4) MeV, which is consistent with phenomenological values obtained using πN scattering data. Our data on one physical pion mass ensemble were crucial for exposing this difference, therefore, calculations on additional physical mass ensembles are needed to confirm our result and resolve the tension between lattice QCD and phenomenology.

PMID:34951792 | DOI:10.1103/PhysRevLett.127.242002

Zh Vopr Neirokhir Im N N Burdenko. 2021;85(6):68-74. doi: 10.17116/neiro20218506168.

ABSTRACT

A ridit analysis of results of transpedicular endoscopic and translaminar microsurgical surgeries for sequester migration to the second and third McCulloch’s windows was carried out. The authors assessed pain syndrome, quality of life and neurological impairment.

OBJECTIVE: To compare the outcomes of transpedicular and translaminar sequestrectomy for lumbar disc herniation and sequester migration to the second and third McCulloch’s windows.

MATERIAL AND METHODS: We analyzed treatment outcomes in 51 patients with lumbar disc herniation and severe sequester migration. We assessed lumbar and leg pain syndrome using then visual analogue scale, neurological impairment using the adapted Nurik scale and quality of life using the Oswestry questionnaire and the MacNab scale in early postoperative period, as well as in 2 weeks, 6 and 12 months after surgery. Ridit analysis was used for statistical processing of data.

RESULTS: Transpedicular sequestrectomy was performed in 24 patients, translaminar sequestrectomy – in 27 cases. Groups were comparable by gender, size and location of sequestration, somatic and neurological status, as well as pain severity. There was a higher probability of back (0.39) and leg (0.364) pain regression, neurological recovery (0.446) and improvement of quality of life according to the Oswestry questionnaire (0.389) after transpedicular surgery. According to the MacNab scoring system, excellent and good results were obtained in 84.21% and 15.79% of patients in 6 months after transpedicular surgery. In the second group, excellent, good and satisfactory results were obtained in 63%, 25.9% and 11.1% of patients, respectively.

CONCLUSION: Herniated intervertebral discs with severe sequester migration should be divided in accordance with localization of the main sequestration. Transpedicular endoscopic approach is advisable for sequester in the third and rarely the second McCulloch’s windows. Translaminar microsurgical approach is preferred for sequestration in the second and rarely the third McCulloch’s windows. Clinical outcomes after translaminar microsurgical sequestrectomy and transpedicular endoscopic surgeries are similar. However, postoperative back and leg pain regression, neurological recovery and improvement of quality of life according to the Oswestry scoring system are more common after transpedicular surgery.

PMID:34951762 | DOI:10.17116/neiro20218506168

Zh Vopr Neirokhir Im N N Burdenko. 2021;85(6):26-35. doi: 10.17116/neiro20218506126.

ABSTRACT

BACKGROUND: One of the most difficult problems in surgical treatment of moyamoya disease is prevention of ischemic perioperative complications. The risk of these events is significantly higher compared to other cerebrovascular diseases (up to 30%).

OBJECTIVE: To identify unfavorable prognostic factors of perioperative cerebral ischemic complications, to determine the group of high-risk patients and to develop the guidelines for perioperative management of these patients.

MATERIAL AND METHODS: We analyzed clinical and diagnostic data and postoperative outcomes in 80 patients with various forms of moyamoya disease. These patients underwent 134 different interventions. Staged revascularization of both hemispheres was performed in 40 patients (80 surgeries). Most patients (n = 55) underwent combined brain revascularization (79 surgeries).

RESULTS: Persistent postoperative complications (ischemic stroke) developed in 7 cases (5.3%). Transient neurological impairment was observed in 36 cases (27%). Statistical analysis revealed the following risk factors of perioperative complications: critical stenosis/occlusion of posterior cerebral artery (OR 9.704), severe perfusion deficit (OR 5.393) and previous TIA or ischemic stroke within 3 months prior to surgery (OR 6.433). If at least two of these signs are present, sensitivity of prognosis for postoperative complications is 80.7% and 88.6%, respectively.

CONCLUSION: Patients with moyamoya disease are at high risk of perioperative complications due to complex rearrangement of collateral cerebral circulation and high sensitivity of brain to local and systemic hemodynamic changes. Patients with risk factors require careful perioperative management to exclude pathogenetic factors provoking ischemia. Early surgical treatment is advisable to reduce the risk of ischemic and hemorrhagic lesions following natural course of disease and severe perioperative complications.

PMID:34951757 | DOI:10.17116/neiro20218506126

J Biophotonics. 2021 Dec 24:e202100340. doi: 10.1002/jbio.202100340. Online ahead of print.

ABSTRACT

Optical coherence tomography angiography (OCTA) can map microvascular networks and quantify blood flow velocities with high resolution by calculating intensity standard deviations of time-series signals. However, statistical calculations of the standard deviations need much processing time and reduce the analysis efficiency. In this study, we proposed three optimized OCTA algorithms incorporating rapid estimations of the intensity standard deviations, including the range algorithm, the mean absolute error algorithm, and the maximum absolute error algorithm. The abilities of the optimized algorithms to quantify the flow velocities were validated by a flow phantom. After a rat cerebral cortex was imaged, the optimized OCTA algorithms were compared with the conventional relative standard deviation algorithm in the metrics of imaging quality and processing time. The results show that the optimized algorithms incorporating rapid estimations of the intensity standard deviations have faster processing speeds with equivalent image quality. This article is protected by copyright. All rights reserved.

PMID:34951745 | DOI:10.1002/jbio.202100340

Int J Dent Hyg. 2021 Dec 24. doi: 10.1111/idh.12572. Online ahead of print.

ABSTRACT

INTRODUCTION: Halitosis is a common oral health problem that significantly impacts the quality of life of the affected individuals. In most cases, poor oral hygiene is responsible for the problem. Orthodontic therapy aims to correct malocclusion using different devices. It has been suggested that orthodontic treatment can promote gingival health by facilitating daily oral hygiene measures. However, the treatment may harm gingival health as these appliances may lead to a more significant accumulation of plaque, increasing the microbial load in the subgingival environment leading to halitosis.

OBJECTIVE: The primary goal of this survey is to assess the prevalence of self-perceived halitosis in patients undergoing orthodontic treatment.

MATERIALS AND METHODS: An online questionnaire was randomly distributed to patients undergoing orthodontic treatment. A total of 289 subjects completed the questionnaire. It included questions about: demographic data, medical history, social habits, past dental treatment, and oral hygiene habits. Descriptive statistics as frequency distributions and percentages were calculated for the study variables.

RESULTS: The prevalence of self-perceived halitosis was 41.5%. The majority of participants started to notice this problem during and after orthodontic treatment (62.5%). A statistically significant correlation was found between the regular dental visits and halitosis in patients with fixed orthodontic appliances(p-value=0.010). Also, those patients had a substantial increase in tongue coating formation(p- value0.010).

CONCLUSION: Self-perceived halitosis is a common problem in patients receiving orthodontic treatment.

PMID:34951749 | DOI:10.1111/idh.12572

Acta Anaesthesiol Scand. 2021 Dec 24. doi: 10.1111/aas.14023. Online ahead of print.

ABSTRACT

BACKGROUND: Respiratory failure is the main cause of mortality and morbidity among ICU patients with coronavirus disease 2019 (COVID-19). In these patients, supplemental oxygen therapy is essential, but there is limited evidence the optimal target. To address this, the ongoing handling oxygenation targets in COVID-19 (HOT-COVID) trial was initiated to investigate the effect of a lower oxygenation target (partial pressure of arterial oxygen (PaO₂ ) of 8 kPa) vs a higher oxygenation target (PaO₂ of 12 kPa) in the ICU on clinical outcome in patients with COVID-19 and hypoxaemia.

METHODS: The HOT-COVID is planned to enrol 780 patients. This paper presents the protocol and statistical analysis plan for the conduct of a secondary Bayesian analysis of the primary outcome of HOT-COVID being days alive without life-support at 90 days and the secondary outcome 90-day all-cause mortality. Further, both outcomes will be investigated for the presence heterogeneity of treatment effects based on four baseline parameters being sequential organ failure assessment score, PaO₂ /fraction of inspired oxygen ratio, highest dose of norepinephrine during the 24 hours before randomisation, and plasma concentration of lactate at randomisation.

CONCLUSION: The results of this pre-planned secondary Bayesian analysis will complement the primary frequentist analysis of the HOT-COVID trial and may facilitate a more nuanced interpretation of the trial results.

PMID:34951717 | DOI:10.1111/aas.14023

Zoo Biol. 2021 Dec 24. doi: 10.1002/zoo.21660. Online ahead of print.

ABSTRACT

The global reach of zoos has enormous potential to raise awareness of conservation issues such as the amphibian extinction crisis. One mechanism of achieving this is through targeted, time-limited campaigns. However, the longer-term impact of such campaigns on conservation outcomes is rarely evaluated. The goal of this study is to evaluate how zoos view “The Year of The Frog,” a campaign launched by zoos in 2008, with the aim of raising awareness of the global amphibian crisis and generating funds to support amphibian conservation initiatives. A questionnaire-based survey of 43 zoos from fourteen countries was used to evaluate how zoo practitioners believed the campaign influenced amphibian conservation some 10 years after its launch. Survey results showed that the campaign not only contributed to the improvement of research into amphibian husbandry in zoos but also increased support of in situ conservation of amphibians. Zoos focused on exotic species, but developed countries led most of the actions of the campaign. The campaign has inspired and encouraged some zoos and other ex situ conservation organizations to embrace amphibian conservation. The next step is to increase collaboration with more organizations through, for example, AArk and IUCN SSC/ASG, particularly in countries that have high amphibian biodiversity.

PMID:34951730 | DOI:10.1002/zoo.21660

J Am Geriatr Soc. 2021 Dec 24. doi: 10.1111/jgs.17633. Online ahead of print.

ABSTRACT

BACKGROUND: Lower urinary tract symptoms (LUTS) are associated with frailty phenotype, a risk factor for functional decline. Our objective was to determine the association between baseline LUTS and 2-year risk of new functional limitation among older men.

METHODS: We analyzed data from the Osteoporotic Fractures in Men (MrOS) study with baseline at Year 7 and follow-up through Year 9. Participants included 2716 community-dwelling men age ≥ 71 years without any baseline self-reported functional limitation. LUTS severity (American Urologic Association Symptom Index) was classified as none/mild (score 0-7), moderate (8-19), and severe (20-35). At baseline and follow-up, men reported their ability to complete several mobility, activities of daily living (ADLs), and cognition-dependent tasks. Risk was estimated for 3 incident functional limitation outcomes: (1) mobility (any difficulty walking 2-3 blocks or climbing 10 steps), (2) ADL (any difficulty bathing, showering, or transferring), and (3) cognition-dependent (any difficulty managing money or medications). We used Poisson regression with a robust variance estimator to model adjusted risk ratios (ARR) and 95% CIs controlling for age, site, and comorbidities; other demographic/lifestyle factors did not meet criteria for inclusion.

RESULTS: Overall, the 2-year risk was 15% for mobility, 10% for ADLs, and 4% for cognition-dependent task limitations. Compared to none/mild LUTS, risk of incident mobility limitations was increased for moderate (ARR = 1.35, 95% CI: 1.12, 1.63) and severe LUTS (ARR = 1.98, 95% CI: 1.48, 2.64). Men were also at higher risk for incident ADL limitations if they reported moderate (ARR = 1.32, 95% CI: 1.05, 1.67) and severe LUTS (ARR = 1.62, 95% CI: 1.07,2.43). Results were somewhat attenuated after adjusting for the frailty phenotype but remained statistically significant. LUTS were not associated with incident cognition-dependent task limitations.

CONCLUSIONS: LUTS severity is associated with incident mobility and ADL limitations among older men. Increased clinical attention to risk of functional limitations among older men with LUTS is likely warranted.

PMID:34951697 | DOI:10.1111/jgs.17633