Maturation level in adolescents: effects on body composition and physical activity changes

Background and aims: Longitudinal studies help move researchers closer to understanding determinants and mediators of maturation, physical activity (PA) and adiposity. The aim of this study was to longitudinally explore the influence of maturation on PA and adiposity changes in adolescents. Methods: Eighty healthy adolescents (42 girls and 38 boys) were followed over three academic years. A PA score was estimated using the Physical Activity Questionnaire (PAQ-A). Fat mass percentage (FMP) was assessed by anthropometric measurements. Sexual maturity was estimated by percentage of predicted adult stature and adolescents were classified into three changes groups: C0, change from on time to late maturation; C1, no change; C2, change from late/on time to on time/early maturation. A stepwise linear regression was conducted in order to estimate the predictors of PA and FMP changes. Results: An interaction between PA and maturation was statically significant (P<0.05). A non-significant trend was observed between three stages of change with a progressive reduction of FMP across the three stages of change in maturation level (C0 = 0.2752.70%; C1= -1.4901.10%; C2= -6.4172.57%; pairwise comparisons: C0 - C2 = 6.69%, P=0.081 and C1-C2 = 4.93%, P=0.080). Conclusions: Our results suggest that body composition changes observed during adolescence are not driven by changes in PA. PA alteration patterns were influenced by sex but not by maturation.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Supported by the Spanish Ministry of Education, Culture and Sport (AP2010-0583); the Spanish Ministry of Economy and Competitiveness (DEP2011-30565

Surface structuring of fused silica with asymmetric femtosecond laser pulse bursts

Fused silica surface structuring has been performed using temporally shaped femtosecond laser pulses. For this purpose we have designed pulse bursts with a triangular intensity envelope and different slope sign and interpulse separation that were experimentally generated using a home-made temporal pulse shaper. We have found that pulse bursts with decreasing intensity envelopes are remarkably more efficient in terms of surface ablation than bursts with increasing intensity envelopes. The results reveal that laser energy coupling in the material is enhanced as the interpulse spacing decreases. A study of the ablation depth using stretched single pulses was carried out and compared to results obtained for pulse bursts with different interpulse spacing. We find that the deepest crater was achieved with bursts of 0.5 ps interpulse separation and decreasing envelope. This pulse form also induced the largest change of the surface reflectivity after irradiation. The results are discussed in terms of how the laser energy coupling efficiency is linked to the temporal pulse shape. © 2013 Optical Society of America.This work has been partially supported by the Spanish TEC2011-22422 project. J. H.-R. acknowledges a grant awarded by the Spanish Ministry of Science and Innovation.Peer Reviewe

A Proposal for a Modified Moller-Plesset Perturbation Theory

A modified version of the Moller-Plesset approach for obtaining the correlation energy associated to a Hartree-Fock ground state is proposed. The method is tested in a model of interacting fermions that allows for an exact solution. Using up to third order terms improved results are obtained, even more accurate in the limit of loosely bound particles. This result suggests the possible convenience of the scheme for the study of chemical bound problems.Comment: 10 pages, 1 figur

Design and Validation of A Modular Instrument to Measure Torque and Energy Consumption in Industrial Operations

A modular torque measuring instrument capable of performing tapping torque tests (TTT) according to the ASTM D-5619 standard was designed, developed, and validated. With this new instrument, the performance of different lubricants can be evaluated in terms of frictional torque and energy consumption during tapping processes. This instrument can adapt onto any conventional milling machine or CNC machine and operate under various machining operations such as tapping, drilling, and other processes. To validate the design and performance of this new device, three commercially available lubricants were evaluated. From the three tested conditions, the results showed good repeatability, with consistent results throughout the different tests for each lubricant. The impact of such a proposed instrument ranges from academic use to industrial business use

A Case Report of Subacute Combined Degeneration Due to Nitrous Oxide-Induced Vitamin B12 Deficiency

Nitrous oxide, also known as “laughing gas,” is a naturally occurring gas that is colorless, odorless, nonflammable, and nontoxic. It has been used as an inhalant anesthetic in the medical field for more than 150 years for dental and surgical procedures. Due to its wide availability and ability to cause euphoria, its recreational use is on the rise. We present a case of subacute combined degeneration (SCD) due to nitrous oxide-induced vitamin B12 deficiency. The patient presented with bilateral lower extremity paresthesia, weakness, and ataxic gait. The patient was found to have vitamin B12 deficiency. An MRI of the cervical spine revealed an abnormal T2 signal within the cervical spinal cord extending from the level of C2-C6 affecting only the posterior column. On the fifth day of hospitalization, the patient reported that he had been inhaling nitric oxide from whipped cream cans for recreational use. According to his clinical presentation and laboratory and imaging findings, we concluded that the patient had SCD. The patient slowly improved after receiving vitamin B12 supplementation therapy. Patients presenting with paresthesia, weakness, and laboratory studies indicating vitamin B12 deficiency should be questioned about nitrous oxide recreational use since the incidence is increasing