Multicomponents of spin-spin relaxation, anisotropy of the echo decay, and nanoporous sample structure

We have experimentally and theoretically investigated multicomponent 1H nuclear magnetic resonance (NMR) echo decays in a-Si:H films containing anisotropic nanopores, in which randomly moving hydrogen molecules are entrapped. The experimental results are interpreted within the framework of the previously developed theory, in which a nanoporous material is represented as a set of nanopores containing liquid or gas, and the relaxation rate is determined by the dipole-dipole spin interaction, considering the restricted motion of molecules inside the pores. Previously, such characteristics of a nanostructure as the average volume of pores and their orientation distribution were determined from the angular dependences of the spin-spin and spin-lattice relaxation times. We propose a new approach to the analysis of the NMR signal, the main advantage of which is the possibility of obtaining nanostructure parameters from a single decay of the echo signal. In this case, there is no need to analyze the anisotropy of the relaxation time T 2 , the determination of which is a rather complicated problem in multicomponent decays. Despite multicomponent signals, the fitting parameter associated with the size and shape of nanopores is determined quite accurately. This made it possible to determine the size and shape of nanopores in a-Si:H films, herewith our estimates are in good agreement with the results obtained by other methods. The fitting of the decays also provides information about the nanostructure of the sample, such as the standard deviations of the angular distribution of pores and the polar and azimuthal angles of the average direction of the pore axes relative to the sample axis, with reasonable accuracy. The approach makes it possible to quantitatively determine the parameters of the non-spherical nanoporous structure from NMR data in a non-destructive manner.

Nanostructure of hydrogenated amorphous silicon (a-Si:H) films studied by nuclear magnetic resonance

The aim of this work is to investigate the nanostructures of nanoporous materials by studying the anisotropy of the nuclear spin-spin and spin-lattice relaxations of the guest molecules trapped in the pores. The nuclear magnetic resonance (NMR) data are analyzed in the framework of the theory of the nuclear relaxation dominated by the dipole-dipole interactions in gas or liquid species contained in nanopores. A distinctive feature of this theory is the establishment of a relationship between the degree of orientation ordering of nanopores in the host matrix and their characteristic volume and the anisotropy of the NMR relaxation times. In this work the complex experimental and theoretical approach was applied to study the nanostructure of hydrogenated amorphous silicon (a-Si:H) films. A feature of this study is the simultaneous investigation of the three (T₁, T_1ρ, and T₂) NMR relaxation times, for the same sample. This allows us to determine not only the degree of orientation ordering of nanopores but also to estimate their size (∼1 nm) and correlation times of the nanopore fluctuations. The obtained results demonstrate that the developed approach is effective in studying details of nanostructure of different nanoporous materials.

Application of deep learning for bronchial asthma diagnostics using respiratory sound recordings

Methods of computer-assisted diagnostics that utilize deep learning techniques on recordings of respiratory sounds have been developed to diagnose bronchial asthma. In the course of the study an anonymous database containing audio files of respiratory sound recordings of patients suffering from different respiratory diseases and healthy volunteers has been accumulated and used to train the software and control its operation. The database consists of 1,238 records of respiratory sounds of patients and 133 records of volunteers. The age of tested persons was from 18 months to 47 years. The sound recordings were captured during calm breathing at four points: in the oral cavity, above the trachea, at the chest, the second intercostal space on the right side, and at the point on the back. The developed software provides binary classifications (diagnostics) of the type: "sick/healthy" and "asthmatic patient/non-asthmatic patient and healthy". For small test samples of 50 (control group) to 50 records (comparison group), the diagnostic sensitivity metric of the first classifier was 88%, its specificity metric -86% and accuracy metric -87%. The metrics for the classifier "asthmatic patient/non-asthmatic patient and healthy" were 92%, 82%, and 87%, respectively. The last model applied to analyze 941 records in asthmatic patients indicated the correct asthma diagnosis in 93% of cases. The proposed method is distinguished by the fact that the trained model enables diagnostics of bronchial asthma (including differential diagnostics) with high accuracy irrespective of the patient gender and age, stage of the disease, as well as the point of sound recording. The proposed method can be used as an additional screening method for preclinical bronchial asthma diagnostics and serve as a basis for developing methods of computer assisted patient condition monitoring including remote monitoring and real-time estimation of treatment effectiveness.

Determining the internal orientation, degree of ordering, and volume of elongated nanocavities by NMR: Application to studies of plant stem

This study investigates the fibril nanostructure of fresh celery samples by modeling the anisotropic behavior of the transverse relaxation time (T₂) in nuclear magnetic resonance (NMR). Experimental results are interpreted within the framework of a previously developed theory, which was successfully used to model the nanostructures of several biological tissues as a set of water filled nanocavities, hence explaining the anisotropy the T₂ relaxation time in vivo. An important feature of this theory is to determine the degree of orientational ordering of the nanocavities, their characteristic volume, and their average direction with respect to the macroscopic sample. Results exhibit good agreement between theory and experimental data, which are, moreover, supported by optical microscopic resolution. The quantitative NMR approach presented herein can be potentially used to determine the internal ordering of biological tissues noninvasively.

Remote Analysis of Respiratory Sounds in Patients With COVID-19: Development of Fast Fourier Transform–Based Computer-Assisted Diagnostic Methods

Background

Respiratory sounds have been recognized as a possible indicator of behavior and health. Computer analysis of these sounds can indicate characteristic sound changes caused by COVID-19 and can be used for diagnostics of this illness.

Objective

The aim of the study is to develop 2 fast, remote computer-assisted diagnostic methods for specific acoustic phenomena associated with COVID-19 based on analysis of respiratory sounds.

Methods

Fast Fourier transform (FFT) was applied for computer analysis of respiratory sound recordings produced by hospital doctors near the mouths of 14 patients with COVID-19 (aged 18-80 years) and 17 healthy volunteers (aged 5-48 years). Recordings for 30 patients and 26 healthy persons (aged 11-67 years, 34, 60%, women), who agreed to be tested at home, were made by the individuals themselves using a mobile telephone; the records were passed for analysis using WhatsApp. For hospitalized patients, the illness was diagnosed using a set of medical methods; for outpatients, polymerase chain reaction (PCR) was used. The sampling rate of the recordings was from 44 to 96 kHz. Unlike usual computer-assisted diagnostic methods for illnesses based on respiratory sound analysis, we proposed to test the high-frequency part of the FFT spectrum (2000-6000 Hz).

Results

Comparing the FFT spectra of the respiratory sounds of patients and volunteers, we developed 2 computer-assisted methods of COVID-19 diagnostics and determined numerical healthy-ill criteria. These criteria were independent of gender and age of the tested person.

Conclusions

The 2 proposed computer-assisted diagnostic methods, based on the analysis of the respiratory sound FFT spectra of patients and volunteers, allow one to automatically diagnose specific acoustic phenomena associated with COVID-19 with sufficiently high diagnostic values. These methods can be applied to develop noninvasive screening self-testing kits for COVID-19.

Anisotropy of Transverse Spin Relaxation in H2O-D2O Liquid Entrapped in Nanocavities: Application to Studies of Connective Tissues

The spin-spin relaxation in connective tissues is simulated using a model in which a connective tissue is represented by a set of nanocavities containing H₂O-D₂O liquid. Collagen fibrils in connective tissues form ordered hierarchical long structures of hydrated nano-cavities with characteristic diameter from 1 nm to several tens of nanometers and length of about 100 nm. We consider influence of the restricted Brownian motion of molecules inside a nano-cavity on spin-spin relaxation. The analytical expression for the transverse time T ₂ for H₂O-D₂O liquid in contained a nanocavity was obtained. We show that the angular dependence of the transverse relaxation rate does not depend on the concentration of D₂O. The theoretical results could explain the experimentally observed dependence of the degree of deuteration on the relaxation time T ₂. Accounting the orientation distribution of the nanocavities well agreement with the experimental dependence of the relaxation for articular cartilage on the deuteration degree was obtained.

Anisotropy of transverse and longitudinal relaxations in liquids entrapped in nano- and micro-cavities of a plant stem

We studied the anisotropy of ¹H NMR spin-lattice and spin-spin relaxations in a fresh celery stem experimentally and modeled the sample theoretically as the water-containing nano- and micro-cavities. The angular dependence of the spin-lattice and the spin-spin relaxation times was obtained, which clearly shows the presence of water-filled nano- and micro-cavities in the celery stem, which have elongated shapes and are related to non-spherical vascular cells in the stem. To explain the experimental data, we applied the relaxation theory developed by us and used previously to interpret similar effects in liquids in nanocavities located in biological tissues such as cartilages and tendons. Good agreement between the experimental data and theoretical results was obtained by adjusting the fitting parameters. The obtained values of standard deviations (0.33 for the mean polar angle and 0.1 for the mean azimuthal angle) indicate a noticeable ordering of the water-filled nano- and micro-cavities in the celery stem. Our approach allows the use of the NMR technique to experimentally determine the order parameters of the microscopic vascular structures in plants.

Dynamics of Zeeman and dipolar states in the spin locking in a liquid entrapped in nano-cavities: Application to study of biological systems

We analyze the application of the spin locking method to study the spin dynamics and spin-lattice relaxation of nuclear spins-1/2 in liquids or gases enclosed in a nano-cavity. Two cases are considered: when the amplitude of the radio-frequency field is much greater than the local field acting the nucleus and when the amplitude of the radio-frequency field is comparable or even less than the local field. In these cases, temperatures of two spin reservoirs, the Zeeman and dipole ones, change in different ways: in the first case, temperatures of the Zeeman and dipolar reservoirs reach the common value relatively quickly, and then turn to the lattice temperature; in the second case, at the beginning of the process, these temperatures are equal, and then turn to the lattice temperature with different relaxation times. Good agreement between the obtained theoretical results and the experimental data is achieved by fitting the parameters of the distribution of the orientation of nanocavities. The parameters of this distribution can be used to characterize the fine structure of biological samples, potentially enabling the detection of degradative changes in connective tissues.

Emotion work and resilience of nurses and physicians towards Palestinian Authority patients

AIM

The purpose of this study was to explore the emotion work and resilience of Israeli healthcare personnel who treat paediatric patients from the Palestinian Authority in Israel.

BACKGROUND

Healthcare personnel deal with internalized emotional conflict deriving from the ethos of health care and the ethos of conflict. Emotion work may be used to overcome emotional conflict, while resilience serves as a protective process against emotional conflict.

METHODS

A mixed methods study among 101 healthcare workers: 84 nurses and 17 physicians. Quantitative data were analysed using IBM SPSS 24.0, and qualitative data were analysed using the constant comparative analysis method.

FINDINGS

Empathy was the highest ranking emotion and contempt was the lowest, for experienced and expected emotions. Positive correlations were found between identification with the ethos of health care and resilience, emotional gap and emotion work, and between the level of Arabic language and emotion work. A negative correlation was found between emotional gap and resilience. The qualitative data yielded three themes: Knowledge of the Arabic language, familiarity with the Arab culture and equitable treatment.

DISCUSSION

The language proficiency of patients belonging to a minority group increases nurses' and physicians' emotion work. Identification with the ethos of health care increases resilience, as both are linked to a sense of vocation and an intrinsic willingness to care for paediatric patients.

CONCLUSION

The study supports the theory of emotion work and refines the role of the ethos of health care in building resilience. Language and cultural capability have a significant role in providing healthcare personnel with methods to treat minorities equitably.

IMPLICATIONS FOR HEALTH POLICY

Hospital managements may supply tailor-made interventions to enhance healthcare personnel's transcultural communication skills, build resilience and cultivate emotion work capabilities. Nursing practice could encourage the use of nursing care plans specific to the individual paediatric patient that can be used by nursing staff to keep care current and applicable.

Spin-lattice relaxation in liquid entrapped in a nanocavity

We consider the spin lattice relaxation in bulk liquid and liquid entrapped in a nanocavity. The kinetic equation which describes the spin lattice relaxation is obtained by using the theory of the nonequilibrium state operator. A solution of the kinetic equation gives the quadrature expression for the relaxation time, T₁. The calculated relaxation time agrees well with the experimental data. The spin-lattice relaxation time is calculated for nanocavities with a characteristic size much less than 700 nm, with the assumption that the spin-lattice relaxation mechanism is determined by nanocavity fluctuations. The resulting expression shows an explicit dependence of the relaxation time T₁ on the volume, density of nuclear spins, and parameters of the cavity (shape and orientation relatively to the applied field). To compare with the experiment on the detection of the anisotropy of the relaxation time, we average the expression that describes the relaxation time over the orientation of the nanocavities relative to the applied magnetic field. The good agreement with the experimental data for fibril tissues was achieved by adjustment of few fitting parameters - the standard deviation, averaged fiber direction, and weight factors - which characterize the ordering of fibrils.

Spin locking in liquid entrapped in nanocavities: Application to study connective tissues

Study of the spin-lattice relaxation in the spin-locking state offers important information about atomic and molecular motions, which cannot be obtained by spin lattice relaxation in strong external magnetic fields. The application of this technique for the investigation of the spin-lattice relaxation in biological samples with fibril structures reveals an anisotropy effect for the relaxation time under spin locking, T_1ρ. To explain the anisotropy of the spin-lattice relaxation under spin-locking in connective tissue a model which represents a tissue by a set of nanocavities containing water is used. The developed model allows us to estimate the correlation time for water molecular motion in articular cartilage, τ_c=30μs and the averaged nanocavity volume, V≃5400nm³. Based on the developed model which represents a connective tissue by a set of nanocavities containing water, a good agreement with the experimental data from an articular cartilage and a tendon was demonstrated. The fitting parameters were obtained for each layer in each region of the articular cartilage. These parameters vary with the known anatomic microstructures of the tissue. Through Gaussian distributions to nanocavity directions, we have calculated the anisotropy of the relaxation time under spin locking T_1ρ for a human Achilles tendon specimen and an articular cartilage. The value of the fitting parameters obtained at matching of calculation to experimental results can be used in future investigations for characterizing the fine fibril structure of biological samples.

Increase in thyroid follicular cell tumors in nelfinavir-treated rats observed in a 2-year carcinogenicity study is consistent with a rat-specific mechanism of thyroid neoplasia

The carcinogenic potential of nelfinavir mesylate (nelfinavir) was evaluated in a 2-year oral (gavage) study on Sprague-Dawley rats at dose levels of 0 (control), 0 (vehicle control), 100, 300 and 1000 mg/kg per day. At the end of the treatment, increased incidences of thyroid follicular cell hyperplasia and neoplasms were observed at 300 (males) and 1000 mg/kg per day (both sexes). There were no other treatment-related effects and no tumors at other sites. Results from previous studies indicated a number of effects in the liver and thyroid, as well as metabolic profiles that suggested nelfinavir might cause thyroid hyperplasia/neoplasia secondary to hormone imbalance by altering thyroid hormone disposition. To investigate this hypothesis, the effects of nelfinavir on gene expression in rat hepatocytes and liver slices (in vitro), thyroxine plasma clearance, and thyroid gland function were evaluated. Compared to controls, gene expression analyses demonstrated an increased expression of glucuronyltransferase (UDPGT) and CYP450 3A1 in nelfinavir-treated rat hepatocytes and liver slices. In rats treated with nelfinavir (1000 mg/kg per day) for 4 weeks, liver weights and centrilobular hepatocellular hypertrophy were increased and minimal to mild diffuse thyroid follicular cell hypertrophy and follicular cell hyperplasia were evident in the thyroid gland. Thyroid-stimulating hormone (TSH) levels were significantly increased (three-fold), while tri-iodothyronine (T3)/tetraiodothyronine (T4) and reverse T3(rT3) levels were unchanged, indicating that a compensated state to maintain homeostasis of T3/T4 had been achieved. Plasma 125I-thyroxine clearance was increased and the plasma thyroxine AUC0 48 was decreased (24%) compared to control. In conclusion, these data indicate that thyroid neoplasms observed in the nelfinavir-treated rats were secondary to thyroid hormone imbalance. Increased thyroxine clearance contributes to the effects of nelfinavir on thyroid gland function and is probably a result of UDPGT induction that leads to elevated TSH levels in the rat and eventual thyroid neoplasia. These results are consistent with a well-recognized rat-specific mechanism for thyroid neoplasms.

Facilitating factors for, barriers to, and outcomes of interdisciplinary education projects in the health sciences

Appropriate collaboration and communication among health professionals is viewed as increasingly important in meeting the challenges of today's health care system. Student socialization to interdisciplinary practice is thought to be facilitated through interdisciplinary academic and clinical learning experiences during the educational program. The purpose of this article is to identify factors commonly cited as facilitating and inhibiting interdisciplinary education, to provide insight for the development of successful interdisciplinary education projects.

Interdisciplinary health professional education: a historical review

A historical review was conducted to examine the advances made, nationally and internationally, in interdisciplinary health professional education since the mid-1960s. One hundred and nineteen articles were reviewed and divided by decade into the following subheadings: models, courses, communication/group process issues, and international perspectives. Twenty-seven articles, categorized as models, defined the conceptual field, described curriculum and program development, or provided a framework for evaluation. Thirty-two articles dealt with interdisciplinary courses, focusing on objectives, content areas, or innovative methods. Nine articles contributed content on interdisciplinary communication and group process issues, from which guidelines were abstracted. Fifty-one articles contributed an international perspective, leading to the recognition that interdisciplinary health professional education, practice, and research is a global movement.

Splenic injury and abscess complicating endoscopic retrograde cholangiopancreatography

A subcapsular hematoma of the spleen was incurred during ERCP and papillotomy. This was complicated by development of a splenic abscess, which was treated by percutaneous drainage.

Effects of student gender and standardized-patient gender in a single case using a male and a female standardized patient

BACKGROUND

In previous studies assessing the effects of student gender, standardized-patient (SP) gender, and their interaction on multiple-station examinations of clinical competence, SP gender was confounded with cases, that is, male SPs were used for some cases and female SPs for others. The authors conducted two studies to investigate the effects of gender on a single case by using a male SP and a female SP for the same case.

METHOD

Both studies involved one SP case in a comprehensive clinical evaluation used to assess fourth-year students at the end of a required ambulatory care clerkship at Saint Louis University School of Medicine in 1990-91 and 1991-92. In Study 1, 45 students in four rotations saw the same male SP; 42 students in three other rotations saw the same female SP. In Study 2, 69 students in six rotations were randomly assigned either the male SP (28) or the female SP (41) within the same rotation. For each study, to determine the interaction of student gender and SP gender as well as their main effects, analyses of variance were performed on the students' history-taking and physical examination scores and communication skills ratings.

RESULTS

Neither study showed a significant interaction of student gender and SP gender on history taking, physical examinations, or communication skills.

CONCLUSION

The findings of both studies suggest that the interaction between student gender and SP gender, unconfounded by case content, had no effect on the students' scores and ratings.

Does sex make a difference? Gender, age, and stimulus realism in perception and evaluation of aggression

Judged aggressiveness and its justifiability were examined with caricature cartoons and films of people doing comparable things. Effects of viewer gender, interactant gender, and facial expression were examined. Facial expression strongly affected both types of judgment, viewer gender had no influence, and interactant gender contributed slightly. Real-cartoon differences were significant, but accounted for little variance. Major response patterns were similar for films of people and cartoons. In two developmental studies, only facial expression influenced judgments of friendliness-hostility in cartoons, but condemnation of aggression decreased as viewer age increased. Results with films of real children followed those for cartoons. Facial expression influenced judged aggressiveness, but only viewer age affected judged justifiability. Cross-experiment comparisons revealed that facial expression and the facial expression X real-cartoon interaction yielded major differences on both dependent variables. Subject and interactant gender were not significant for major dependent variables. Results of the developmental studies were similar to adults' suggesting that for judgments of simple aggressive acts, sex makes no difference, but facial expression does make a difference.