Epidemic model on a network: Analysis and applications to COVID-19.

We analyze an epidemic model on a network consisting of susceptible-infected-recovered equations at the nodes coupled by diffusion using a graph Laplacian. We introduce an epidemic criterion and examine different isolation strategies: we prove that it is most effective to isolate a node of highest degree. The model is also useful to evaluate deconfinement scenarios and prevent a so-called second wave. The model has few parameters enabling fitting to the data and the essential ingredient of importation of infected; these features are particularly important for the current COVID-19 epidemic.

Effects of a calcium supplement on bone mineral density in male cyclists.

AIM: The purpose of this study was to maintain or improve bone density in male road cyclists through provision of calcium and vitamin D3 supplementation ingested before cycling. METHODS: Participants were male cyclists (N=17), with a mean (±SD) age of 42.7 (9.4) years. Measurements of lumbar spine and hip areal bone mineral density (aBMD) were performed at the start and end of a cycling season. Cyclists were randomized into the calcium supplement (CAL) or the control group (CON) group based on lumbar spine T-scores. The CAL group was instructed to consume 1600 mg calcium and 1000 IU vitamin D3 prior to cycling for the 5-month period. RESULTS: Femoral trochanter aBMD significantly decreased during the 5 month cycling season. There was no difference in aBMD between CAL and CON groups. CONCLUSION: Negative effects of competitive cycling on aBMD in hip structures can be observed within 5 months. Calcium and vitamin D3 ingested prior to cycling does not ameliorate this effect. This proof of concept paper provides evidence that more work is needed to find mechanisms to protect cyclists from destructive bone loss in hip structures.

Radial sine-Gordon kinks as sources of fast breathers.

We consider radial sine-Gordon kinks in two, three, and higher dimensions. A full two-dimensional simulation showing that azimuthal perturbations remain small allows us to reduce the problem to the one-dimensional radial sine-Gordon equation. We solve this equation on an interval [r(0),r(1)] and absorb all outgoing radiation. As the kink shrinks toward r(0), before the collision, its motion is well described by a simple law derived from the conservation of energy. In two dimensions for r(0)≤2, the collision disintegrates the kink into a fast breather, while for r(0)≥4 we obtain a kink-breather metastable state where breathers are shed at each kink "return." In three and higher dimensions d, an additional kink-oscillon state appears for small r(0). On the application side, the kink disintegration opens the way for new types of terahertz microwave generators.

Masticatory performance and taste perception in patients submitted to cancer treatment.

The aim of this study was to analyse mastication and the sense of taste in 39 patients submitted to cancer treatment in different areas of the body and to compare these variables with those of 44 control individuals within the same age range. The following aspects were assessed: dental status (DMFT); stimulated and non-stimulated salivary flow; sense of taste (salty, sweet, bitter and sour); and masticatory performance (MP), through the calculation of X(50). Logistic regression models were established to test the association between the independent variables and cancer treatment. Cancer patients had lesser stimulated salivary flow, a smaller number of teeth and occlusal units, worse MP, higher salty, sweet and sour taste scores and a lower bitter taste score (P < 0·05). A significant positive correlation was found between MP and the DMFT index in both groups (P < 0·05), meaning that a lower DMFT index value denoted a smaller X(50) value (better masticatory performance). The logistic regression model revealed that patients who had undergone cancer treatment had a greater probability of exhibiting a smaller number of teeth, higher salty and smaller bitter taste scores (P < 0·05). It was concluded that patients who were submitted to cancer treatment presented oral physiology alterations when compared with control subjects at the same age range.

Fourier-mode dynamics for the nonlinear Schrödinger equation in one-dimensional bounded domains.

We analyze the 1D focusing nonlinear Schrödinger equation in a finite interval with homogeneous Dirichlet or Neumann boundary conditions. There are two main dynamics, the collapse which is very fast and a slow cascade of Fourier modes. For the cubic nonlinearity the calculations show no long-term energy exchange between Fourier modes as opposed to higher nonlinearities. This slow dynamics is explained by fairly simple amplitude equations for the resonant Fourier modes. Their solutions are well behaved so filtering high frequencies prevents collapse. Finally, these equations elucidate the unique role of the zero mode for the Neumann boundary conditions.

Validity and reliability of the BOD POD® S/T tracking system.

BOD POD(®) self-testing (S/T) body composition tracking system is a practical assessment tool designed for use in the health and fitness industries. Relative to its parent counterpart, the BOD POD(®) S/T has received little research attention. The primary purpose was to determine the validity of the BOD POD(®) S/T against hydrostatic weighing and 7-site skinfolds. Secondary aim was to determine the within-day and between-day reliability of the BOD POD(®) S/T. After a period of equipment and testing accommodation, volunteer's (N=50) body composition (%BF) via 7-site skinfolds, BOD POD(®) S/T, and hydrostatic weighing were obtained on the second and third visits. BOD POD(®) S/T significantly overestimated %BF when compared to hydrostatic weighing and 7-site skinfolds. There was no statistical difference between 7-site skinfolds and hydrostatic weighing values. BOD POD(®) S/T reliability within-day and between-days were high. While the BOD POD(®) S/T body composition tracking system is deemed reliable both within-day and between-days, it did significantly overestimate %BF in comparison to hydrostatic weighing and skinfolds. Future research should be aimed at deriving a correction factor for this body composition assessment tool.

The influence of respiratory muscle training upon intermittent exercise performance.

The purpose of this study was to determine the effect of respiratory muscle training (RMT) on intermittent exercise performance, respiratory muscle strength (PI (max)), respiratory muscle fatigue (RMF), and dyspnea in soccer athletes. Collegiate soccer athletes (20 male, 7 female) were randomly divided into either a RMT or control condition during off-season conditioning. The RMT group performed a 30RM protocol (10 times weekly) for 5 weeks using a commercially-available training device, while the controls received no RMT. Performance was evaluated utilizing Level 1 of the Yo-Yo Intermittent Recovery Test (IRT) and dyspnea was assessed during and immediately following the IRT. RMF was quantified within 2 minutes (RMF2) and 10 minutes (RMF10) after completing the IRT. Following training, the RMT group significantly increased IRT performance by 216.6 +/- 231.0 meters (p = .008) while the 49.2 +/- 75.1 meter increase observed in the controls was not significant. PI (max) in the RMT group increased from 138.1 +/- 19.6 to 165.3 +/- 23.5 cmH (2)O (p < .001), with no significant change observed in the controls. RMT did not significantly affect RMF or dyspnea. In conclusion, RMT improved intermittent exercise performance in these soccer athletes. The mechanisms by which RMT improves performance warrant further study.

Stimulated Raman scattering with strong damping: a simple theory of the spike phenomenon.

The classical stimulated Raman scattering system describing the resonant interaction between two electromagnetic waves and a fast relaxing medium wave is studied by introducing a systematic perturbation approach in powers of the relaxation time. We separate amplitude and phase effects for these complex fields. The analysis of the former shows the existence of a stagnation distance after which monotonic energy transfer begins from one electromagnetic wave to the other, and this quantity is calculated. Concerning phase effects we give the conditions for the formation of a Raman spike from an initial fast and large phase jump in one of the waves. The spike evolution and width estimated from the reduced model agree with the results from numerical simulations of the original system.

Interrelationships among thigh muscle co-contraction, quadriceps muscle strength and the aerobic demand of walking in children with cerebral palsy.

The purpose of this study was to quantify interrelationships among thigh muscle co-contraction, quadriceps muscle strength, and the aerobic demand of walking in 13 children with spastic hemiplegic cerebral palsy (CP). During Session 1, subjects were familiarized with testing procedures, given five minutes of treadmill walking practice, and completed quadriceps muscle strength testing. In Session 2, subjects performed three 5-min walking bouts on the treadmill at 0.67 m x s(-1) to further accommodate to treadmill ambulation. During Session 3, resting VO2 was measured and subjects walked at 0.67, 0.89, and 1.12 m x s(-1) for five minutes while oxygen uptake (VO2) and thigh muscle co-contraction data were collected. Results demonstrated that no significant relationship existed between net VO2 and measures of thigh muscle co-contraction or quadriceps muscle strength. In addition, thigh muscle co-contraction was not shown to be associated with quadriceps muscle strength. Collectively, thigh muscle co-contraction and quadriceps muscle strength explained 13. 5%, 6.2%, and 2.2% of the variance in VO2 at 0.67, 0.89, and 1.12 m x s(-1), respectively. Viewed in concert, these results suggest that the walking energy expenditure of children with spastic hemiplegic CP is not influenced by the level of thigh muscle co-contraction or quadriceps muscle strength.

Metabolic accommodation of young children to treadmill walking.

Few data exist concerning the reproducibility of stable oxygen uptake (VO(2)) values during level treadmill walking in young able-bodied children. To address this issue, 41 able-bodied 6-year-olds (19 boys, 22 girls, X height=117.2+/-4.7 cm, X body mass=21.8+/-2.5 kg) were tested on two occasions. In session 1, subjects were familiarized with the laboratory environment and performed 5 min of level treadmill walking at 1.34 m s(-1). During session 2, each child completed 30 min (three 10-min trials) of level treadmill walking at 1.34 m s(-1). For each 10-min trial, mean VO(2) was determined by averaging VO(2) values obtained from analysis of two 2-min expired gas samples. While the mean VO(2) for trial 1 was higher than values recorded for trials 2 and 3, effect sizes corresponding to these differences were low (

Perceived stress and blood pressure in early adolescent children.

The objective of this investigation was to determine the individual contributions of perceived daily, major, and total stressors to blood pressure in early adolescent children. Toward this goal, cardiovascular risk factors were assessed in 74 6th-grade students. Height and body weight, measured in standard fashion, were used to calculate body mass index (BMI). Waist and hip circumferences and triceps and calf skinfolds were taken to determine the distribution and percentage of body fat, respectively. Seated resting blood pressure was obtained using a mercury sphygmomanometer. The dietary sodium-to-potassium ratio was calculated from a food intake questionnaire. Family history of hypertension was self-reported by participant's parents, and physical activity and perceived stress levels were determined by questionnaire. When added to the hierarchical regression models, the perceived stress variables did not significantly predict any additional variance in systolic or diastolic blood pressure in this early adolescent sample. Additionally, bivariate correlations between the stress variables and blood pressure were nonsignificant. The nonpsychological hypertension risk factors accounted for 25%-35% of the total variance in systolic and diastolic blood pressure. Further, regression analyses revealed that with the exception of BMI and the sodium-to-potassium ratio, no other risk factors were independent predictors of systolic or diastolic blood pressure. Further identification and understanding of environmental precursors of childhood hypertension is recommended.

Cutaneous metastatic lung cancer: literature review and report of a tumor on the nose from a large cell undifferentiated carcinoma.

Cutaneous metastatic disease is a prognostically important diagnosis. We report the case of a 64-year-old man who had an uncommon histologic type of lung cancer--a large cell undifferentiated carcinoma, which was metastatic to the skin of the nose. The relative frequency of cutaneous metastasis is similar to that of primary cancers. Cutaneous disease as the first sign of metastasis is most often seen in cancer of the lung. However, its appearance as a large tumor on the nose, which was observed in this case, is unusual.

Stability of running economy in young children.

Few studies have been conducted documenting the length of time required for young children to achieve stable measures of running economy. Hence the purpose of this study was to quantify within- and between-day stability in running economy among young children. To address this issue, 30 6-year olds (16 girls, 14 boys) completed three test sessions within a 2 wk period. During Sessions 1 and 2 subjects performed three 5 min level treadmill runs at 2.23 m x sec(-1). During Session 2 expired air was collected during the last 2 min of each 5 min run (R1, R2, R3) and analyzed to determine VO2. In Session 3 subjects completed a single 5 min run (R4) at 2.23 m x sec(-1) and VO2 was measured during the last 2 min of running. Data analysis revealed no significant difference (p>0.05) in absolute or relative VO2 across trials. The average coefficient of variation for both absolute and relative VO2 among runs completed in Session 2 was 2.17 %, and the mean coefficient of variation for VO2 between R4 and the average VO2 of R1, R2, and R3 was 2.51 % and 2.35% for absolute and relative VO2, respectively. Moreover intraclass correlation coefficients for absolute and relative VO2 across all runs were 0.99 and 0.96, respectively. Viewed in concert, these results suggest that following 15 minutes of level treadmill running practice, stable within- and between-day measures of running economy can be obtained in young, prepubescent children.

Pharmacokinetics of ceftiofur sodium in exotic and domestic avian species.

The pharmacokinetics of ceftiofur sodium were determined in domestic chicks, turkey poults, adult cockatiels (Nymphicus hollandicus), and adult orange-winged Amazon parrots (Amazona amazonica) after subcutaneous (chicks and turkey poults and intramuscular (i.m.) dosing (cockatiels and Amazon parrots). Turkey poult data were best fit to a single exponential model with disappearance half-lives (t1/2) of 8.6, 7.4 and 5.6 h after doses of 0.12, 0.24 and 0.48 mg ceftiofur free acid equivalents (CFAE)/poult, respectively. Data from chicks were best fit to a biexponential model with primary and secondary half-lives of 2.2 and 7.5, 3.7 and 6.8, and 3.8 and 5.3 h after doses of 0.04, 0.08 and 0.16 mg CFAE/chick, respectively. Cockatiel and Amazon parrot data were best fit to a biexponential model with primary and secondary half-lives of 0.28 and 2.5, and 0.93 and 7.9 h, respectively, after doses of 10 mg CFAE/kg body weight. The maximum concentration (Cmax) and area under the concentration time curve (AUC) in chicks and poults were dose-proportional. The Cmax for cockatiels was 5.2 micrograms/mL and for Amazon parrots was 11 micrograms/mL. Clearance in cockatiels and Amazon parrots were 11.3 and 3.8 mL/min/kg, respectively, and reflected the much greater AUC seen in Amazon parrots. Clearance values of ceftiofur were similar in chicks and Amazon parrots, slightly greater in turkey poults and greatest in cockatiels. These results indicate that pharmacokinetic differences must be considered when establishing dosage regimens for different avian species.

Influence of positive life events on blood pressure in adolescents.

It has been reported that adults suffering from refractory essential hypertension experience significantly fewer positive life events than healthy peers. However, the influence of positive life events on blood pressure (BP) in adolescents has been largely ignored. Therefore, we examined the relationship between self-reported positive life events and BP in 69 sixth graders with a mean age of 11.7 years. Positive life events were assessed with the Adolescent Perceived Events Scale and resting blood pressure was measured with a mercurial sphygmomanometer. Correlational analyses showed an inverse relationship between positive life events and diastolic BP, suggesting that adolescents experiencing more positive life events were more likely to have lower diastolic BP's. Hierarchical regression analyses revealed that physical activity level, dietary sodium-to-potassium ratio, parental history of hypertension, and measures of body composition predicted 24.6% of the variance in systolic BP and 34.6% of the variance in diastolic BP. Moreover, positive life events predicted an additional 4.3% of the variance in diastolic BP when statistically controlling these established risk factors for hypertension. These results suggest that increased perceptions of positive life events may act as a buffer to elevated BP in adolescents.

Disaster strikes the caregivers. A lesson for managers.

The caregiving team is the core of effective management practice. Home care managers need to remember that caring for the caregivers--seeing them as victims as well as care providers and allowing them the same time for shock, grief, and recovery--allows those folks to carry on with the business of home care.

Case study. ESRD after living-related donation.

The patient met three of the four expected outcomes. He has in the past and is currently making informed decisions. reguarding his health care. Momentarily, he is demonstrating effective, positive coping strategies and problem-solving techniques. However, the fourth, and probably most critical outcome, is not being met. A.J. has not remained free of complications secondary to his kidney donation. It is estimated that he is facing ESRD, and all related medical and nursing regimens in less than 1 year. Additionally related to his elective nephrectomy, he will experience the loss of his 12-year military career and associated benefits. Although the nursing interventions were instrumental in assisting A.J. and his wife to cope with his acute situation, they now face the fears and anxieties of lifetime chronic illness. Theoretically, this patient may have experienced chronic renal failure at some point in his life, but the nursing intervention could have been approached as a pre-ESRD patient, in lieu of his status as a postliving related donor patient.

A graph-theoretical approach to the prediction of physical properties of alkanes based on the distance matrix.

A new topological index, the largest eigenvalue of the distance matrix (DI), is presented as a measure of molecular branching. The DI and Balaban's J index are used to predict the densities of a series of alkanes. The statistical correlations obtained are excellent and give a correlation coefficient of 0.961.