This study investigated changes in heart rate variability (HRV) in elite Nordic-skiers to characterize different types of "fatigue" in 27 men and 30 women surveyed from 2004 to 2008. R-R intervals ...were recorded at rest during 8 min supine (SU) followed by 7 min standing (ST). HRV parameters analysed were powers of low (LF), high (HF) frequencies, (LF+HF) (ms(2)) and heart rate (HR, bpm). In the 1 063 HRV tests performed, 172 corresponded to a "fatigue" state and the first were considered for analysis. 4 types of "fatigue" (F) were identified: 1. F(HF(-)LF(-))SU_ST for 42 tests: decrease in LFSU (- 46%), HFSU (- 70%), LFST (- 43%), HFST (- 53%) and increase in HRSU (+ 15%), HRST (+ 14%). 2. F(LF(+) SULF(-) ST) for 8 tests: increase in LFSU (+ 190%) decrease in LFST (- 84%) and increase in HRST (+ 21%). 3. F(HF(-) SUHF(+) ST) for 6 tests: decrease in HFSU (- 72%) and increase in HFST (+ 501%). 4. F(HF(+) SU) for only 1 test with an increase in HFSU (+ 2161%) and decrease in HRSU (- 15%). Supine and standing HRV patterns were independently modified by "fatigue". 4 "fatigue"-shifted HRV patterns were statistically sorted according to differently paired changes in the 2 postures. This characterization might be useful for further understanding autonomic rearrangements in different "fatigue" conditions.
Epidemiology of spontaneous pneumothorax has been scantily studied. We aimed to assess the incidence of spontaneous pneumothorax and describe patients' characteristics with respect to age, sex, ...seasonal occurrence, primary or secondary character, surgical management and rehospitalisations on a large-scale database.
Data from all patients aged ≥14 years and hospitalised with a diagnosis of non-traumatic pneumothorax in France from 2008 to 2011 were retrieved from the National Hospitalisation Database.
There were 59 637 hospital stays corresponding to 42 595 patients. Twenty-eight per cent of patients were rehospitalised at least once during the 4-year period. Annual rate of pneumothorax could be estimated at 22.7 (95% CI 22.4 to 23.0) cases for 100 000 habitants. The women to men ratio was 1:3.3. Mean age was significantly higher in women than in men (41±19 vs 37±19 years, p<0.0001). No seasonal variation was observed. A surgical procedure was performed in 14 352 hospital stays (24%). In the group of patients aged <30 years, there was no statistical difference between men and women with regard to type of pneumothorax (primary or secondary), type of hospitalisation unit (surgery vs medicine), treatment modality (surgery or not), intensive care unit (ICU) admission and hospital stay duration. Rehospitalisation was more frequent in women than in men (56% vs 52%, p<0.0001). In the 30-49 years age group, surgery and rehospitalisation were more frequent in women than in men (each, p<0.001). In the 50-64 years age group, surgical procedures and rehospitalisations were more frequent in men than in women (p=0.002 and p<0.0001, respectively).
Sex and age are determinant factors in the course of spontaneous pneumothorax.
An experimental investigation of the noise radiated by a ducted high pressure flow discharge through diaphragms and perforated plates is carried out for a large range of subsonic and supersonic ...operating conditions (Nozzle Pressure Ratio (NPR) from 1.2 to 3.6). A parametric study of the geometrical parameters is also conducted to characterize their influence on the acoustic radiation. This covers configurations from single diaphragms to multi-perforated plates with variable hole diameters and arrangements that are placed inside a cylindrical duct. Compared with the free discharge analysed in a first part of the study (perforated plates placed directly at the output of the duct), the discharge into a duct, which is closer to the practical applications, generates strong acoustic modifications. As expected, the broadband noise is disturbed by strong modulations due to acoustic resonances in the output duct (longitudinal resonances and transversal duct modes). However, as in the free configuration, a strong effect of the plate geometries on the mixing noise is observed, allowing to adapt or reduce this source. In particular, the increase of the ratio between the perforation spacing and the perforation diameter allows reducing the maximum amplitude of the mixing noise. Compared to the free-field discharge, the Sound Pressure Level (SPL) in the ducted configuration is on average proportional to the 6-th power of the velocity instead of the 8-th power. Moreover, there are two dominant frequency humps in the sound spectra. The low frequency one is characterized by a constant Helmholtz number, suggesting that the sound is shaped by the duct geometry, whereas the high frequency one is characterized by a constant Strouhal number suggesting that the sound is directly generated by the flow. Finally, for supersonic operating points, the screech radiation appearing with diaphragms in the free configuration is suppressed when the output duct is added but new high amplitude and low frequency tones appear for the largest diaphragms and perforated plates. These lines are due to a coupling between normal shock oscillations and longitudinal resonances.
The cold pressor test (CPT) triggers in healthy subjects a vascular sympathetic activation and an increase in blood pressure. The heart rate (HR) response to this test is less well defined, with a ...high inter-individual variability. We used traditional spectral analysis together with the non-linear detrended fluctuation analysis to study the autonomic control of HR during a 3-min CPT. 39 healthy young subjects (23.7+/-3.2 years, height 180.4+/-4.7 cm and weight 73.3+/-6.4 kg) were divided into two groups according to their HR responses to CPT. Twenty subjects have a sustained increase in HR throughout the test with reciprocal autonomic interaction, i.e. increase in sympathetic activity and decrease vagal outflow. In the 19 remainders, HR decreased after an initial increase, with indication of involvement of both sympathetic and vagal outflow. Baseline evaluation of the subjects revealed no difference between the two groups. Nevertheless, a higher sympathetic activity at the skin level during CPT was present in the group with decreased HR. Further studies are needed to explain why healthy subjects react differently to the CPT and if this has potential clinical implications.
An experimental analysis of the noise radiated by a high pressure flow discharge through diaphragms and perforated plates is carried out for a large range of subsonic and supersonic operating ...conditions (nozzle pressure ratio (NPR) from 1 to 3.6). A parametric study of the geometrical parameters is also achieved to characterize their influence onto the acoustic radiation and ways to reduce it. This reaches from single diaphragms to multi-perforated plates with variable hole diameters and arrangements that are placed at the exit of a duct. Different acoustic behaviors are observed: in all cases the far-field acoustic radiation is dominated by a broadband contribution associated with the turbulent mixing in shear layers. In the diaphragm cases, this broadband noise has similar characteristics as the mixing noise of classical unheated jets while in the multi-perforated plates cases, it is composed of two distinct humps associated with different parts of the jets development. For supersonic regimes, in addition to this broadband radiation, shock associated noise (screech and broadband shock associated noise) appears for all diaphragm cases and for the perforated plate with the closest holes. Finally for the smallest NPR, a high frequency tonal noise has been observed in most of the multi-perforated cases and for the smallest diaphragm. Different regimes of this radiation have also been observed with a possible amplitude modulation of the dominant tone. This radiation may be attributed to vortex shedding due to the sharp section reduction that would trigger a flow resonance between the small ducts of the holes and their sharp edges.
Évaluer chez six adolescents obèses, les effets d’un réentraînement à l’effort intermittent, individualisé de 30 séances, 50
minutes, trois fois par semaine sur les paramètres cardiorespiratoires et ...métaboliques au repos et à l’exercice.
À l’issue du programme, la masse grasse a diminué (10,8 %) alors que l’IMC reste inchangé. Le volume de réserve expiratoire s’est amélioré (44,6 %). La puissance maximale aérobie, le pouls d’oxygène, la ventilation maximale ont augmenté (12,4 % ; 16,9 % ; 17,2 % respectivement) et les seuils d’adaptation et de désadaptation ventilatoires ont été repoussés (26,1 % et 17,3 %).
Cet entraînement se révèle efficace sur les fonctions cardiorespiratoires de l’adolescent obèse.
To assess in six obese teenagers, the effects of 30 sessions (three days/week) of 50-minute individualised interval training on cardiorespiratory and metabolic parameters at rest and during exercise.
After this programme, fat mass decreases (10.8%) while BMI did not change. The expiratory reserve volume improved (44.6%). Maximal aerobic power, oxygen pulse and maximal ventilation are higher (12.4%; 16.9%; 17.2% respectively). First and second ventilatory threshold are increased (26.1% and 17.3%).
This study demonstrates the efficiency of this individualised training programme for obese teenagers. Such a programme may therefore provides additional benefits in weight management of obesity.
BACKGROUND AND AIMS: Leaf responses to environmental conditions have been frequently described in fruit trees, but differences among cultivars have received little attention. This study shows that ...parameters of Farquhar's photosynthesis and Jarvis' stomatal conductance models differed between two apple cultivars, and examines the consequences of these differences for leaf water use efficiency. METHODS: Leaf stomatal conductance (gsw), net CO₂ assimilation rate (An), respiration (Rd) and transpiration (E) were measured during summer in 8-year-old 'Braeburn' and 'Fuji' apple trees under well-watered field conditions. Parameters of Farquhar's and Jarvis' models were estimated, evaluated and then compared between cultivars. Leaf carbon isotope discrimination (Δ¹³C) was measured at the end of the growing season. KEY RESULTS: A single positive relationship was established between VCmax (maximum carboxylation rate) and Na (leaf nitrogen concentration per unit area), and between Jmax (maximum light-driven electron transport rate) and Na. A higher leaf Rd was observed in 'Fuji'. The gsw responded similarly to increasing irradiance and leaf temperature in both cultivars. gsw responded to lower vapour pressure deficit in 'Fuji' than in 'Braeburn'. Maximal conductance (gswmax) was significantly smaller and An was more limited by gsw in 'Braeburn' than 'Fuji'. Lower gsw, E and higher intrinsic water use efficiency were shown in 'Braeburn' and confirmed by smaller leaf Δ¹³C compared with 'Fuji' leaves. CONCLUSIONS: The use of functional model parameters allowed comparison of the two cultivars and provided evidence of different water use 'strategies': 'Braeburn' was more conservative in water use than 'Fuji', due to stomatal limitation of An, higher intrinsic water use efficiency and lower Δ¹³C. These physiological traits need to be considered in relation to climate adaptation, breeding of new cultivars and horticultural practice.
Until recently, the reference equations available for pulmonary function tests (PFTs) have had several weaknesses: they have often been based on relatively weak samples of normal subjects; they used ...mathematical models that are not very efficient in describing the evolution of PFTs over age; there were different equations for children/adolescents and for adults; the expression of the results solely as a percentage of the predicted value did not provide a good indication of the statistical significance of any difference that may exist between a measured value and its reference value. The Global Lung Initiative (GLI) aimed to establish new reference equations for PFTs that do not have these disadvantages. Based on large, representative, reference populations and allowing individualization of homogeneous ethnic groups over a wide age range, the GLI uses a statistical model that does not have any a priori hypothesis regarding the evolution of PFTs as a function of age (these models therefore make it possible to describe, in a very precise manner, the PFTs over all age ranges). For a given PFT, the equation is the same regardless of age (no discontinuity on transition to adulthood). The GLI equations are used to define a reference value, a threshold value (lower limit of the normal) and a z-score that take into account age, sex, size and, for some PFTs, ethnicity. The reference equations of the GLI were established in 2012 for spirometry, in 2017 for the TLCO and will soon be established for lung volumes. Already the representation of ethnic groups not identified by the GLI and of subjects with extreme values of age and size is being questioned.
BACKGROUND
Catamenial pneumothorax and thoracic endometriosis (TE) are still under diagnosed. The purpose of this study is to increase the diagnostic accuracy for these conditions in patients with ...spontaneous pneumothorax and to identify their risk factors.
METHODS
We conducted a retrospective study on all consecutive women of reproductive age referred to our Centre for surgical treatment of spontaneous pneumothorax between July 2000 and January 2009.
RESULTS
The study population comprised 156 premenopausal women of whom 49 (31.4%) had catamenial and/or TE-related pneumothorax. Over a quarter of these 49 patients had a previous history of recurrent thoracic or scapular catamenial pain. They experienced their first pneumothorax episode at an older age (mean ± SD) (34.0 years ± 6.7) than women with idiopathic pneumothorax (28.7 ± 6.1 years, P < 0.001). Pelvic endometriosis was found in 51% of women with catamenial and/or TE-related pneumothorax. After adjustment for confounding factors by multiple logistic regression analysis, the results show that, infertility odd ratio (OR) = 4.21, 95% confidence interval (CI) = 1.28–13.88 and a history of pelvic surgery with a uterine procedure and/or uterine scraping (OR = 2.85, 95% CI = 1.12–7.26) were the strongest predictors of catamenial and/or TE-related pneumothorax.
CONCLUSIONS
Infertility and uterine procedures are significantly associated with catamenial and/or TE-related pneumothorax. Scapular or thoracic pain during menses often precedes the occurrence of pneumothorax and is highly specific for the diagnosis of TE. Our results suggest that in women with pelvic endometriosis, these symptoms should be systematically investigated for an earlier diagnosis of TE.
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