Tag: statistics

Phys Chem Chem Phys. 2021 Sep 27. doi: 10.1039/d1cp03116c. Online ahead of print.

ABSTRACT

The energy dependence of the rates of the reactions between He⁺ and ammonia (NY₃, Y = {H,D}), forming NY₂⁺, Y and He as well as NY⁺, Y₂ and He, and the corresponding product branching ratios have been measured at low collision energies E_coll between 0 and k_B·40 K using a recently developed merged-beam technique [Allmendinger et al., ChemPhysChem, 2016, 17, 3596]. To avoid heating of the ions by stray electric fields, the reactions are observed within the large orbit of a highly excited Rydberg electron. A beam of He Rydberg atoms was merged with a supersonic beam of ammonia using a curved surface-electrode Rydberg-Stark deflector, which is also used for adjusting the final velocity of the He Rydberg atoms, and thus the collision energy. A collision-energy resolution of about 200 mK was reached at the lowest E_coll values. The reaction rate coefficients exhibit a sharp increase at collision energies below ∼k_B·5 K and pronounced deviations from Langevin-capture behaviour. The experimental results are interpreted in terms of an adiabatic capture model describing the rotational-state-dependent orientation of the ammonia molecules by the electric field of the He⁺ atom. The model faithfully describes the experimental observations and enables the identification of three classes of |JKMp〉 rotational states of the ammonia molecules showing different low-energy capture behaviour: (A) high-field-seeking states with |KM| ≥ 1 correlating to the lower component of the umbrella-motion tunnelling doublet at low fields. These states undergo a negative linear Stark shift, which leads to strongly enhanced rate coefficients; (B) high-field-seeking states subject to a quadratic Stark shift at low fields and which exhibit only weak rate enhancements; and (C) low-field-seeking states with |KM| ≥ 1. These states exhibit a positive Stark shift at low fields, which completely suppresses the reactions at low collision energies. Marked differences in the low-energy reactivity of NH₃ and ND₃-the rate enhancements in ND₃ are more pronounced than in NH₃-are quantitatively explained by the model. They result from the reduced magnitudes of the tunnelling splitting and rotational intervals in ND₃ and the different occupations of the rotational levels in the supersonic beam caused by the different nuclear-spin statistical weights. Thermal capture rate constants are derived from the model for the temperature range between 0 and 10 K relevant for astrochemistry. Comparison of the calculated thermal capture rate coefficients with the absolute reaction rates measured above 27 K by Marquette et al. (Chem. Phys. Lett., 1985, 122, 431) suggests that only 40% of the close collisions are reactive.

PMID:34569565 | DOI:10.1039/d1cp03116c

Phys Chem Chem Phys. 2021 Sep 27. doi: 10.1039/d1cp00783a. Online ahead of print.

ABSTRACT

This paper offers an expedient, efficient, and unique treatment of multimode quantum subsystems (polyatomic molecules) interacting with a classical environment in which the time evolution of the coupling term is governed by the algebraic rules of statistical mechanics in mixed quantum-classical systems developed by Kapral and Nielsen [S. Nielsen, R. Kapral, and G. Ciccotti, J. Chem. Phys., 2001, 115, 5805]. This unique time evolution of the coupling term is neither quantal nor classical but rather something different that relies heavily on Wigner transform, thereby leading to non-Newtonian mechanics. As such, an argument is presented that the approach provided herein for treating polyatomic molecular systems in a mixed quantum-classical environment is new and different as opposed to the many other schemes of semiclassical dynamics that are normally employed to study such systems. The merits of expediency and efficiency of the herein mixed quantum-classical dynamics calculations emanate from avoiding using integrals for time evolutions, and, instead, employing matrix mechanics whereby LU decomposition and singular value decomposition (SVD) numerical techniques are utilized for diagonalization. An electronic 2-level subsystem interacting with a classical bath through the spin-boson model to render accurate pure electronic dephasing in multimode molecular systems by eliminating the unphysical asymmetry in the line shape of the zero-phonon line (ZPL) exhibited by other models is exploited. This work has a superior advantage over the single-mode spin-boson model, published previously, whereby a multitude of types of vibrational modes (slow, fast, or both) of the quantum subsystem may readily be handled using different spectral densities. The spin-boson model used here is a composite system made up of a quantum subsystem, i.e., a subsystem bilinearly coupled to a multidimensional harmonic oscillator (representing the intermediate quantum vibrational modes between the electronic subsystem and the bath), interacting with a classical bath, where the coupling term is governed by the mixed quantum-classical Liouville equation. A multidimensional coherent-state approach is employed to deal with the time evolution of the quantum subsystem. A closed-form expression of linear and nonlinear optical electronic transition dipole moment time correlation functions in mixed quantum-classical dissipative media is derived. Pure electronic dephasing is probed using the aforementioned approach. Linear absorption spectra and 4-wave mixing signals (e.g., photon echo and pump-probe) are calculated showing a reasonable thermal broadening, temporal decay, and accurate pure dephasing.

PMID:34569571 | DOI:10.1039/d1cp00783a

Gerontology. 2021 Sep 21:1-15. doi: 10.1159/000518822. Online ahead of print.

ABSTRACT

OBJECTIVE: Age-related macular degeneration(AMD) has become a major cause of visual impairment worldwide, especially in the elderly. Estimates of incidence, progression rates, and risk factors of AMD vary among studies, complicating the understanding of its epidemiology.

METHODS: For this systematic review and meta-analysis, literature published up to March 1, 2021, was searched in both English and Chinese databases. Hierarchical Bayesian approaches were used to estimate pooled incidence, progression, and 95% credible intervals (CrIs).

RESULTS: Thirty studies were included. The pooled annual early and late AMD incidence rates were 1.59 (95% CrI: 1.18-2.11) and 0.23 (95% CrI: 0.14-0.34) per 100 person-years, respectively. The annual progression rate of AMD was 5.5 (95% CrI: 2.3-8.8) per 100 person-years. Smoking was an independent risk factor for both early and late AMD, whereas age, high-density lipoprotein cholesterol, and alcohol consumption were risk factors for early AMD incidence only. The projected number of new cases of early and late AMD in 2050 would be 39.05 million (95% CrI: 23.12-63.57) and 6.41 million (95% CrI: 3.37-13.22), respectively.

CONCLUSION: The prediction the number of new cases of AMD is not equal across the globe. Our findings indicate the need for more rigorous control and prevention measures in AMD focus on its risk factors for early intervention. The epidemiological estimates reported in this study could inform to identify effective strategies for preventing AMD worldwide.

PMID:34569526 | DOI:10.1159/000518822

Neonatology. 2021 Sep 17:1-7. doi: 10.1159/000518986. Online ahead of print.

ABSTRACT

BACKGROUND: In late preterm infants born in nontertiary hospitals, the occurrence of respiratory distress syndrome requires postnatal transport. This study aimed to investigate the impact of the timing of surfactant administration in late preterm infants needing postnatal transport.

METHODS: This is a retrospective study evaluating surfactant administration in late preterm infants during emergency transports by the Eastern Veneto Neonatal Emergency Transport Service between January 2005 and December 2019. The outcome measures included short-term clinical complications, stabilization time, oxygen concentration, duration of mechanical ventilation and noninvasive respiratory support, length of hospital stay, bronchopulmonary dysplasia, intraventricular hemorrhage, and sepsis.

RESULTS: Surfactant was administered to 155/303 neonates (51.1%) at 3 different time points: at a referring hospital (50 neonates), when the transport team arrived (25 neonates), or at a referral hospital (80 neonates). Stabilization time was longer in neonates receiving surfactant by the transport team (adjusted mean difference 17 min, 95% confidence interval, 4-29 min; p = 0.01). Decrease in oxygen concentrations during the transport was larger in neonates receiving surfactant at a referring hospital (adjusted mean difference -11%, 95% confidence interval, -15 to -3%; p = 0.01). The other outcome measures were not statistically different according to the timing of surfactant administration.

CONCLUSIONS: In late preterm infants with respiratory distress needing postnatal transfer, stabilization time was longer when the first surfactant was administered by the transport team, but such delay did not affect safety and clinical outcomes.

PMID:34569541 | DOI:10.1159/000518986

Eur Surg Res. 2021 Sep 16:1-9. doi: 10.1159/000518403. Online ahead of print.

ABSTRACT

OBJECTIVES: The present study aimed to identify significant causes of readmission within 30 days following coronary artery bypass graft (CABG) surgery and compare readmission incidence related to surgical site infections (SSIs) before and after implementing international recommendations for antibiotic prophylaxis.

METHODS: We analyzed 2,225 CABG patients who received either guideline-directed antibiotic prophylaxis (GDAP = 568) or institutional antibiotic prophylaxis (non-GDAP = 1,657) between January 2017 and December 2019. The primary outcome was a composite of sternal wound infection (SWI) or harvest SWI. Secondary outcomes consisted of the individual components of composite end point, the incidence of in-hospital SSIs, and prolonged postoperative length of hospital stay (LOS) (>7 days). Propensity matching was used to select pairs for final comparison.

RESULTS: Before implementing GDAP, the most frequent reason for readmission were SSIs, causing 58.2% of all readmissions within 30 days. Of 429 matched pairs, 48 patients in the GDAP group and 67 patients in the non-GDAP group were readmitted to a hospital within 30 days for any cause (11.2 vs. 15.6%, p = 0.048). We found a decreased readmission incidence for reasons related to SSIs, although these differences did not reach statistical significance (7.4 vs. 10.0%, p = 0.069). Adherence to GDAP was associated with reduced in-hospital risks of SSIs and prolonged postoperative LOS (19.6 vs. 26.6%, p = 0.015).

CONCLUSIONS: In this contemporary clinical practice study, the adherence to GDAP was an insufficient measure to decrease rehospitalization due to SSIs. The present findings warrant further investigation on factors that may contribute to SSIs development after hospital discharge.

PMID:34569485 | DOI:10.1159/000518403

Dement Geriatr Cogn Disord. 2021 Sep 16:1-7. doi: 10.1159/000519054. Online ahead of print.

ABSTRACT

BACKGROUND: Frailty syndrome is characterized by a decline in physiological and psychological reserve and may be associated with poor health outcomes.

OBJECTIVES: The current study explored frailty and its correlates among cognitively intact community-dwelling older adults.

METHODS: A secondary analysis of data collected from 109 community-dwelling older adults who are cognitively intact was conducted for the purpose of this study. The Arabic versions of the culturally adapted Tilburg Frailty Indicator, the Montreal Cognitive Assessment, the Geriatric Depression Scale, and the Short Form-36 Quality of Life (QOL) survey. Multiple linear regression was used to examine the relationships between frailty and depression.

RESULTS: The results indicated a high prevalence of frailty (78%) and depression (38%) among cognitively intact community-dwelling older adults. Frailty was found to be associated with increased age, being single or illiterate, living alone, having a high number of comorbid conditions, having high rate of depression, and having poor QOL.

CONCLUSION: High prevalence of frailty is associated with high depression scores, a high number of comorbid conditions, and poor QOL among cognitively intact community-dwelling older adults.

PMID:34569493 | DOI:10.1159/000519054

Ann Ital Chir. 2021 Sep 14;10:S0003469X21036289. Online ahead of print.

ABSTRACT

BACKGROUND AND OBJECTIVES: Laparoscopic surgery is a widely used surgical technique, whose benefits either for patients or for surgeons are well-recognized. Despite the rise in the use of this technique, the ergonomics of the operating room is still very low. The consequence is that injuries and illness related to laparoscopic surgery are present. The aims of this study are to investigate how an increase in the surgeon’ perception of the fatigue during the execution of the intervention influences the surgeon’ health, and to evaluate if there is a correlation between the increase in fatigue and the operating field dimension.

MATERIALS AND METHODS: The observation was conducted on a single laparoscopist working at our Institution and the Borg CR 0-10 scale was used to perform this study. Two groups of 20 surgical procedures each were analysed. Group A included laparoscopic procedures whose operating field comprehended only one abdominal quadrant. Group B included laparoscopic procedures where at least two abdominal quadrants were involved in the operative field.

RESULTS: The results from both groups were statistically compared. There was a significant correlation between the increase in perception of the exertion and duration of the intervention in both groups and a significant difference in term of Borg scale value, which was higher in group B where the laparoscopic surgery was performed on more than one quadrant of the abdomen.

CONCLUSION: We suggest an important improvement in the ergonomic aspects, especially in more complex laparoscopic procedures that require longer operating time and include more than one abdominal quadrant.

KEY WORDS: Ergonomics, Laparoscopic surgery, Operating theatre.

PMID:34569477

Dermatology. 2021 Sep 16:1-8. doi: 10.1159/000518625. Online ahead of print.

ABSTRACT

BACKGROUND: The fecal immunochemistry test (FIT) has been proposed as a surrogate marker of intestinal inflammation. Psoriasis is a chronic inflammatory skin disease that is linked to underlying systemic inflammatory conditions, including inflammatory bowel disease.

METHODS: We investigated the association between occult blood in feces and the risk of psoriasis using data from the National Health Insurance System. This study was conducted involving 1,395,147 individuals who underwent health examinations from January 2009 to December 2012 and were followed up until the end of 2017.

RESULTS: The incidence of psoriasis (per 1,000 person-years) was 3.76 versus 4.14 (FIT-negative versus FIT-positive group) during a median follow-up of 6.68 years. In the multivariable-adjusted model, the hazard ratios for psoriasis were 1.03 for one positive FIT result, 1.12 for two positive FIT results, and 1.34 for three positive FIT results compared with negative FIT results.

CONCLUSION: The risk of psoriasis was significantly increased in patients with positive FIT results compared to the FIT-negative population.

PMID:34569483 | DOI:10.1159/000518625

Cranio. 2021 Sep 26:1-8. doi: 10.1080/08869634.2021.1982496. Online ahead of print.

ABSTRACT

OBJECTIVE: To evaluate the prevalence/severity of somatic and temporomandibular disorder (TMD) symptoms in Southeast Asian youths and determine their associations with psychological distress.

METHODS: Demographic information, Patient Health Questionnaire-15 (PHQ-15), Fonseca Anamnestic Index (FAI), and Depression, Anxiety, Stress Scale-21 (DASS-21) responses were gathered electronically and analyzed using non-parametric statistical and logistic regression analysis (p < 0.05).

RESULTS: Of 400 youths (mean age 18.7 ± 1.7 years; 52.3% females), 65.0%/47.0% reported somatic/TMD symptoms, and 10.5% had TMDs. Significant differences in psychological distress were observed among the varying severity of somatic/TMD symptoms. Correlations between PHQ-15/FAI and DASS-21 scores were weak to moderately strong (r_s = 0.30-0.61). Stepwise logistic regression indicated that female gender, TMD symptoms, and stress were risk factors for somatic symptoms, while somatic symptoms and stress were probable factors for TMDs.

CONCLUSION: Somatic and TMD symptoms are common in Southeast Asian youths and may be a manifestation of psychological distress.

PMID:34569454 | DOI:10.1080/08869634.2021.1982496

JMIR Form Res. 2021 Sep 26. doi: 10.2196/31064. Online ahead of print.

ABSTRACT

BACKGROUND: There is growing evidence suggesting that the emotional wellbeing of the general public has been negatively affected within the past year. Consequently, there has been an increase in demand for wellbeing support. Whilst there is substantial empirical support for mental health apps that target diagnosed conditions, there is less research on emotional wellbeing apps. Amongst existing wellbeing apps, few studies have been conducted on apps that are based on lived experience and those that seek to enhance user’s understanding of their emotional patterns. Thus, the acceptability of these novel apps will require further evaluation before upscaling.

OBJECTIVE: The primary aim of this evaluation is to describe the acceptability, engagement, and preliminary outcomes of using an app (Paradym) designed to promote emotional wellbeing and positive mental health.

METHODS: This is a pre- and post -mixed methods single-arm evaluation, aggregate with digital analytics data. We anonymously collected real world data on demographics, wellbeing, usability and acceptance of the app using validated questionnaires and open-ended questions. Participants tested the app for a minimum of 2 weeks before completing follow up measures. Google Analytics was used to record levels of app engagement. Chi Square and t-tests were conducted to analyze quantitative data, and a thematic analysis approach was adopted for qualitative data.

RESULTS: A total of 115 participants completed baseline questionnaires, of which 91 (79.13%) users downloaded the app. The sample was diverse in terms of ethnicity, including 50 (43.5%) people self-identifying as belonging to minority ethnic groups. The majority of the sample were females (78, 67.24%) and between the ages 18-25 (39, 33.62%). Thirty-four app users who completed questionnaires at baseline and follow-up provided valuable feedback to inform future directions of Paradym. Favorable themes emerged describing the app’s content, functionality and underlying principles. Although usability feedback varied across items, a considerable number of participants (22, 64.7%) found that the app was easy to use. Google Analytics revealed that at least 27 (80%) persons used the app on a daily basis. Based on preliminary observations, app users experienced increased mental wellbeing. Post hoc analyses indicated that the reduction in depression scores (t33 = -2.16) and the increase on the wellbeing measures (t33 = 2.87) were statistically significant. No adverse events were reported during the evaluation period.

CONCLUSIONS: The findings of this evaluation are encouraging and document positive preliminary evidence for the Paradym app.

PMID:34569466 | DOI:10.2196/31064