955 resultados para stretching


Relevância:

10.00% 10.00%

Publicador:

Resumo:

My Portfolio of Exploration tackles the difficult question as to whether adult mental development can be accelerated and if so how. Rooted in constructive-developmental ideas, adult mental development is explained as an evolutionary unfolding of human capability. Going beyond this I look at the possibility of advancing development as transformational growth in adulthood in the belief that a broader perspective leads to increased effectiveness in professional life. Initially I explored my own meaning making, to make sense of my experiences, knowledge, relationships and my own motivations. This exploration has provided me with a ‘developmental bridge’ between my current way of knowing and a new more enlightened way. I have come to view my way of making meaning in the world as an evolving and progressive sequence of emotional and cognitive development. Through the formation of new stretching experiences, increased self - awareness and reflection my previous perspective has been overtaken by a more complex form of being aware of myself, others and the world. I refer to this process of growth as transformation. As part of my own transformational work I have conducted an inquiry into transformational growth and learning in the early academic life of university undergraduates. The result shows how accelerated adult mental development can be achieved in an academic environment ably preparing students for the workplace. This new model of education is part of a truly unique and exciting model signalling ground-breaking change for the undergraduate experience. The overhaul of a traditional BA degree in Economics into a world-class transformational programme is discussed through-out my Portfolio. Central to my broadening awareness is the challenge and nurturing required to awaken the student’s ‘internal authority’ . This involves stimulating students to take ownership for their own thinking, steering them away from the passivity and complacency of thinking through the minds of others. In doing so, the ultimate aim of renewing the BA is to narrow the developmental ‘mismatch’ which exists for m any college students between them and the world of work, by encouraging and inviting them to take on the challenge of thinking independently. Mindfulness, awareness, and personal authority are treated with reverence throughout the exploration as I consider them core parts of the students engaging with development. Engagement is construed as an active and open-minded process of awareness involving planning and reviewing one’s own goals and performance, engaging in constructive feedback, reflection and new action. I conclude with a view that the journey of adult mental development is relentless and that undergraduate education represents a crucial beginning. The value and relevance of transformational education rooted in developmental principles provides a significant opportunity in advancing development and perspectives at the start of adult life.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

BACKGROUND: The Lung Cancer Exercise Training Study (LUNGEVITY) is a randomized trial to investigate the efficacy of different types of exercise training on cardiorespiratory fitness (VO2peak), patient-reported outcomes, and the organ components that govern VO2peak in post-operative non-small cell lung cancer (NSCLC) patients. METHODS/DESIGN: Using a single-center, randomized design, 160 subjects (40 patients/study arm) with histologically confirmed stage I-IIIA NSCLC following curative-intent complete surgical resection at Duke University Medical Center (DUMC) will be potentially eligible for this trial. Following baseline assessments, eligible participants will be randomly assigned to one of four conditions: (1) aerobic training alone, (2) resistance training alone, (3) the combination of aerobic and resistance training, or (4) attention-control (progressive stretching). The ultimate goal for all exercise training groups will be 3 supervised exercise sessions per week an intensity above 70% of the individually determined VO2peak for aerobic training and an intensity between 60 and 80% of one-repetition maximum for resistance training, for 30-45 minutes/session. Progressive stretching will be matched to the exercise groups in terms of program length (i.e., 16 weeks), social interaction (participants will receive one-on-one instruction), and duration (30-45 mins/session). The primary study endpoint is VO2peak. Secondary endpoints include: patient-reported outcomes (PROs) (e.g., quality of life, fatigue, depression, etc.) and organ components of the oxygen cascade (i.e., pulmonary function, cardiac function, skeletal muscle function). All endpoints will be assessed at baseline and postintervention (16 weeks). Substudies will include genetic studies regarding individual responses to an exercise stimulus, theoretical determinants of exercise adherence, examination of the psychological mediators of the exercise - PRO relationship, and exercise-induced changes in gene expression. DISCUSSION: VO2peak is becoming increasingly recognized as an outcome of major importance in NSCLC. LUNGEVITY will identify the optimal form of exercise training for NSCLC survivors as well as provide insight into the physiological mechanisms underlying this effect. Overall, this study will contribute to the establishment of clinical exercise therapy rehabilitation guidelines for patients across the entire NSCLC continuum. TRIAL REGISTRATION: NCT00018255.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

BACKGROUND: The Exercise Intensity Trial (EXcITe) is a randomized trial to compare the efficacy of supervised moderate-intensity aerobic training to moderate to high-intensity aerobic training, relative to attention control, on aerobic capacity, physiologic mechanisms, patient-reported outcomes, and biomarkers in women with operable breast cancer following the completion of definitive adjuvant therapy. METHODS/DESIGN: Using a single-center, randomized design, 174 postmenopausal women (58 patients/study arm) with histologically confirmed, operable breast cancer presenting to Duke University Medical Center (DUMC) will be enrolled in this trial following completion of primary therapy (including surgery, radiation therapy, and chemotherapy). After baseline assessments, eligible participants will be randomized to one of two supervised aerobic training interventions (moderate-intensity or moderate/high-intensity aerobic training) or an attention-control group (progressive stretching). The aerobic training interventions will include 150 mins.wk⁻¹ of supervised treadmill walking per week at an intensity of 60%-70% (moderate-intensity) or 60% to 100% (moderate to high-intensity) of the individually determined peak oxygen consumption (VO₂peak) between 20-45 minutes/session for 16 weeks. The progressive stretching program will be consistent with the exercise interventions in terms of program length (16 weeks), social interaction (participants will receive one-on-one instruction), and duration (20-45 mins/session). The primary study endpoint is VO₂peak, as measured by an incremental cardiopulmonary exercise test. Secondary endpoints include physiologic determinants that govern VO₂peak, patient-reported outcomes, and biomarkers associated with breast cancer recurrence/mortality. All endpoints will be assessed at baseline and after the intervention (16 weeks). DISCUSSION: EXCITE is designed to investigate the intensity of aerobic training required to induce optimal improvements in VO₂peak and other pertinent outcomes in women who have completed definitive adjuvant therapy for operable breast cancer. Overall, this trial will inform and refine exercise guidelines to optimize recovery in breast and other cancer survivors following the completion of primary cytotoxic therapy. TRIAL REGISTRATION: NCT01186367.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Solid-state protonated and N,O-deuterated Fourier transform infrared (IR) and Raman scattering spectra together with the protonated and deuterated Raman spectra in aqueous solution of the cyclic di-amino acid peptide cyclo(L-Asp-L-Asp) are reported. Vibrational band assignments have been made on the basis of comparisons with previously cited literature values for diketopiperazine (DKP) derivatives and normal coordinate analyses for both the protonated and deuterated species based upon DFT calculations at the B3-LYP/cc-pVDZ level of the isolated molecule in the gas phase. The calculated minimum energy structure for cyclo(L-Asp-L-Asp), assuming C-2 symmetry, predicts a boat conformation for the DKP ring with both the two L-aspartyl side chains being folded slightly above the ring. The C=O stretching vibrations have been assigned for the side-chain carboxylic acid group (e.g. at 1693 and 1670 cm(-1) in the Raman spectrum) and the cis amide I bands (e.g. at 1660 cm(-1) in the Raman spectrum). The presence of two bands for the carboxylic acid C=O stretching modes in the solid-state Raman spectrum can be accounted for by factor group splitting of the two nonequivalent molecules in a crystallographic unit cell. The cis amide II band is observed at 1489 cm(-1) in the solid-state Raman spectrum, which is in agreement with results for cyclic di-amino acid peptide molecules examined previously in the solid state, where the DKP ring adopts a boat conformation. Additionally, it also appears that as the molecular mass of the substituent on the C-alpha atom is increased, the amide II band wavenumber decreases to below 1500 cm(-1); this may be a consequence of increased strain on the DKP ring. The cis amide II Raman band is characterized by its relatively small deuterium shift (29 cm(-1)), which indicates that this band has a smaller N-H bending contribution than the trans amide II vibrational band observed for linear peptides.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Cyclo(L-Glu-L-Glu) has been crystallised in two different polymorphic forms. Both polymorphs are monoclinic, but form 1 is in space group P21 and form 2 is in space group C2. Raman scattering and FT-IR spectroscopic studies have been conducted for the N,O-protonated and deuterated derivatives. Raman spectra of orientated single crystals, solid-state and aqueous solution samples have also been recorded. The different hydrogen-bonding patterns for the two polymorphs have the greatest effect on vibrational modes with N&bond;H and C&dbond;O stretching character. DFT (B3-LYP/cc-pVDZ) calculations of the isolated cyclo(L-Glu-L-Glu) molecule predict that the minimum energy structure, assuming C2 symmetry, has a boat conformation for the diketopiperazine ring with the two L-Glu side chains being folded above the ring. The calculated geometry is in good agreement with the X-ray crystallographic structures for both polymorphs. Normal coordinate analysis has facilitated the band assignments for the experimental vibrational spectra. Copyright © 2009 John Wiley & Sons, Ltd.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Solvent-cast films from three polymers, carboxymethylcellulose (CMC), sodium alginate (SA), and xanthan gum, were prepared by drying the polymeric gels in air. Three methods, (a) passive hydration, (b) vortex hydration with heating, and (c) cold hydration, were investigated to determine the most effective means of preparing gels for each of the three polymers. Different drying conditions [relative humidity - RH (6-52%) and temperature (3-45 degrees C)] were investigated to determine the effect of drying rate on the films prepared by drying the polymeric gels. The tensile properties of the CMC films were determined by stretching dumbbell-shaped films to breaking point, using a Texture Analyser. Glycerol was used as a plasticizer, and its effects on the drying rate, physical appearance, and tensile properties of the resulting films were investigated. Vortex hydration with heating was the method of choice for preparing gels of SA and CMC, and cold hydration for xanthan gels. Drying rates increased with low glycerol content, high temperature, and low relative humidity. The residual water content of the films increased with increasing glycerol content and high relative humidity and decreased at higher temperatures. Generally, temperature affected the drying rate to a greater extent than relative humidity. Glycerol significantly affected the toughness (increased) and rigidity (decreased) of CMC films. CMC films prepared at 45 degrees C and 6% RH produced suitable films at the fastest rate while films containing equal quantities of glycerol and CMC possessed an ideal balance between flexibility and rigidity.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Temperate reefs are superb tractable systems for testing hypotheses in ecology and evolutionary biology. Accordingly there is a rich history of research stretching back over 100 years, which has made major contributions to general ecological and evolutionary theory as well as providing better understanding of how littoral systems work by linking pattern with process. A brief resumé of the history of temperate reef ecology is provided to celebrate this rich heritage. As a community, temperate reef ecologists generally do well designed experiments and test well formulated hypotheses. Increasingly large datasets are being collected, collated and subjected to complex meta-analyses and used for modelling. These datasets do not happen spontaneously – the burgeoning subject of macroecology is possible only because of the efforts of dedicated natural historians whether it be observing birds, butterflies, or barnacles. High-quality natural history and old-fashioned field craft enable surveys or experiments to be stratified (i.e. replicates are replicates and not a random bit of rock) and lead to the generation of more insightful hypotheses. Modern molecular approaches have led to the discovery of cryptic species and provided phylogeographical insights, but natural history is still required to identify species in the field. We advocate a blend of modern approaches with old school skills and a fondness for temperate reefs in all their splendour.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

During free surface moulding processes such as thermoforming and blow moulding heated polymer materials are subjected to rapid biaxial deformation as they are drawn into the shape of a mould. In the development of process simulations it is therefore essential to be able to accurately measure and model this behaviour. Conventional uniaxial test methods are generally inadequate for this purpose and this has led to the development of specialised biaxial test rigs. In this paper the results of several programmes of biaxial tests conducted at Queen’s University are presented and discussed. These have included tests on high impact polystyrene (HIPS), polypropylene (PP) and aPET, and the work has involved a wide variety of experimental conditions. In all cases the results clearly demonstrate the unique characteristics of materials when subjected to biaxial deformation. PP draws the highest stresses and it is the most temperature sensitive of the materials. aPET is initially easier to form but exhibits strain hardening at higher strains. This behaviour is increased with increasing strain rate but at very high strain rates these effects are increasingly mollified by adiabatic heating. Both aPET and PP (to a lesser degree) draw much higher stresses in sequential stretching showing that this behaviour must be considered in process simulations. HIPS showed none of these effects and it is the easiest material to deform.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

We have carried out extensive density functional theory (DFT) calculations for possible redox states of the active center in Fe-only hydrogenases. The active center is modeled by [(H(CH(3))S)(CO)(CN(-))Fe(p)(mu-DTN)(mu-CO)Fe(d)(CO)(CN(-))(L)](z) (z is the net charge in the complex; Fe(p)= the proximal Fe, Fe(d) = the distal Fe, DTN = (-SCH(2)NHCH(2)S-), L is the ligand that bonds with the Fed at the trans position to the bridging CO). Structures of possible redox states are optimized, and CO stretching frequencies are calculated. By a detailed comparison of all the calculated structures and the vibrational frequencies with the available experimental data, we find that (i) the fully oxidized, inactive state is an Fe(II)-Fe(II) state with a hydroxyl (OH(-)) group bonded at the Fe(d), (ii) the oxidized, active state is an Fe(II)-Fe(l) complex which is consistent with the assignment of Cao and Hall (J. Am. Chem. Soc. 2001, 123, 3734), and (iii) the fully reduced state is a mixture with the major component being a protonated Fe(l)-Fe(l) complex and the other component being its self-arranged form, Fe(II)-Fe(II) hydride, Our calculations also show that the exogenous CO can strongly bond with the Fe(II)-Fe(l) species, but cannot bond with the Fe(l)-Fe(l) complex. This result is consistent with experiments that CO tends to inhibit the oxidized, active state, but not the fully reduced state. The electronic structures of all the redox states have been analyzed. It is found that a frontier orbital which is a mixing state between the e(g) of Fe and the 2pi of the bridging CO plays a key role concerning the reactivity of Fe-only hydrogenases: (1) it is unoccupied in the fully oxidized, inactive state, half-occupied in the oxidized, active state, and fully occupied in the fully reduced state; (ii) the e(g)-2pi orbital is a bonding state, and this is the key reason for stability of the low oxidation states, such as Fe(l)-Fe(l) complexes; and (iii) in the e(g)-2pi orbital more charge accumulates between the bridging CO and the Fe(d) than between the bridging CO and the Fe(p), and the occupation increase in this orbital will enhance the bonding between the bridging CO and the Fe(d), leading to the bridging-CO shift toward the Fe(d).

Relevância:

10.00% 10.00%

Publicador:

Resumo:

[M2L3] coordination cages and linear [M2L3]infinity polymers of the rigid, bridging diphosphines bis(diphenylphosphino)acetylene (dppa) and trans-1,2-bis(diphenylphosphino)ethylene (dppet) with silver(I) salts have been investigated in the solution and solid states. Unlike flexible diphosphines, 1:1 dppa/AgX mixtures do not selectively form discrete [Ag2(diphos)2(X)2] macrocycles; instead dynamic mixtures of one-, two- and three-coordinate complexes are formed. However, 3:2 dppa/AgX ratios (X = SbF6. BF4, O3SCF3 or NO3) do lead selectively to new [M2L3] triply bridged cage complexes [Ag2(dppa)3(X)2] 1a-d (X = SbF6 a, BF4 b, O3SCF3 c, NO3 d), which do not exhibit Ag-P bond dissociation at room temperature on the NMR time scale (121 MHz). Complexes la-d were characterised by X-ray crystallography and were found to have small internal cavities, helical conformations and multiple intramolecular aromatic interactions. The nucleophilicity of the anion subtly influences the cage shape: Increasing nucleophilicity from SbF6 (1a) through BF4 (1b) and O3SCF3 (1c) to NO3 (1d) increases the pyramidal distortion at the AgP3 centres, stretching the cage framework (with Ag...Ag distances increasing from 5.48 in 1a to 6.21 A in 1d) and giving thinner internal cavities. Crystal packing strongly affected the size of the helical twist angle, and no correlation between this parameter and the Ag-Ag distance was observed. When crystalline 1c was stored in its supernatant for 16 weeks, conversion occured to the isostoichiometric [M2L3]infinity coordination polymer [Ag(dppa)2Ag(dppa)(O3SCF3)2]infinity (1c'). X-ray crystallography revealed a structure with ten-membered Ag2(dppa)2 rings linked into infinite one-dimensional chains by a third dppa unit. The clear structural relationship between this polymer and the precursor cage 1c suggests a novel example of ring-opening polymerisation. With dppet, evidence for discrete [M2L3] cages was also found in solution, although 31P NMR spectroscopy suggested some Ag-P bond dissociation. On crystallisation, only the corresponding ring-opened polymeric structures [M2L3]infinity could be obtained. This may be because the greater steric bulk of dppet versus dppa destabilises the cage and favours the ring-opening polymerisation.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

A semi-phenomenological model describing wideband dielectric and far-infrared spectra of liquid water was proposed recently by the same authors [J. Mol. Struct. 606 (2002) 9], where a small dipole-moment component changing harmonically with time determines a weak absorption band (termed here the R-band) centred at the wavenumber v similar to 200 cm(-1). In the present work, a rough molecular theory of the R-band based on the concept of elastic interactions is given. Stretching and bending of hydrogen bonds cause restricted rotation (RR) of a polar water molecule in terms of a dimer comprising the H- bonded molecules. Analytical expression for the RR frequency nu(str) is derived as a function of the RR amplitude, geometrical parameters and force constants. The density g(nu(str)) of frequency distribution is shown to be centred in the R-band. The spectrum of the dipolar auto-correlation function calculated for this structural-dynamical model is found. A composite model comprising two intermolecular potentials is proposed, which yields for water a good description of the experimental wideband (from 0 to 1000 cm(- 1)) spectra of complex permittivity and of absorption coefficient. The presented interpretation of these spectra is based on a concept that water presents a two-component solution, with components differing by the types of molecular rotation. (C) 2003 Elsevier B.V. All rights reserved.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

A semi-phenomenological molecular model is presented, which is capable of describing with the use of analytical formulae, the wideband dielectric(1) and far-infrared spectra of ordinary and heavy water. In the model the vector of a dipole moment is presented as a sum of two components. The absolute value of the first one is constant; the second one changes harmonically with time. The key aspect of this work is consideration of FIR spectra due to the second component. In the context of the modified hybrid model presented in the work, reorientation of the dipoles in the rectangular potential well is considered, as a result of which the librational (near 700 cm (-1)) and translational (near 200 cm (-1)) absorption bands and the microwave Debye relaxation spectrum arise. It is shown that the time-dependent part of a dipole moment contributes most to the translational band, the relevant mechanism is taken to be stretching vibration of the H-bonded molecules. Previous linear-response molecular models were unsuccessful in describing this band (in heavy water) in terms of the complex dielectric permittivity. The spatial and time scales characteristic of water are estimated. (C) 2002 Elsevier Science B.V. All rights reserved.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The work presented here is aimed at determining the potential and limitations of Raman spectroscopy for fat analysis by carrying out a systematic investigation of C-4-C-24 FAME. These provide a simple, well-characterized set of compounds in which the effect of making incremental changes can be studied over a wide range of chain lengths and degrees of unsaturation. The effect of temperature on the spectra was investigated over much larger ranges than would normally be encountered in real analytical measurements. It was found that for liquid FAME the best internal standard band was the carbonyl stretching vibration nu(C = O), whose position is affected by changes in sample chain length and physical state; in the samples studied here, it was found to lie between 1729 and 1748 cm(-1). Further, molar unsaturation could be correlated with the ratio of the nu(C = O) to either nu(C = C) or delta(H-C = ) with R-2 > 0.995. Chain length was correlated with the delta(CH2)(tw)/nu(C = O) ratio, (where "tw" indicates twisting) but separate plots for odd- and even-numbered carbon chains were necessary to obtain R-2 > 0.99 for liquid samples. Combining the odd- ani even-numbered carbon chain data in a single plot reduced the correlation to R-2 = 0.94-0.96, depending on the band ratios used. For molal unsaturation the band ratio that correlated linearly with unsaturation (R-2 > 0.99) was nu(C = C)/delta(CH2)(SC) (where "sc" indicates scissoring). Other band ratios show much more complex behavior with changes in chemical and physical structure. This complex behavior results from the fact that the bands do not arise from simple vibrations of small, discrete regions of the molecules but are due to complex motions of large sections of the FAME so that making incremental changes in structure does not necessarily lead to simple incremental changes in spectra.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Tunnel ionization of room-temperature D-2 in an ultrashort (12 femtosecond) near infrared (800 nm) pump laser pulse excites a vibrational wavepacket in the D-2(+) ions; a rotational wavepacket is also excited in residual D-2 molecules. Both wavepacket types are collapsed a variable time later by an ultrashort probe pulse. We isolate the vibrational wavepacket and quantify its evolution dynamics through theoretical comparison. Requirements for quantum computation (initial coherence and quantum state retrieval) are studied using this well-defined (small number of initial states at room temperature, initial wavepacket spatially localized) single-electron molecular prototype by temporally stretching the pump and probe pulses.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The nature of the surface species formed at the surface of 2 wt.% Pt/CeO2 catalyst during the forward water-gas-shift (WGS, CO + H2O -> CO2 + H-2) and the reverse reaction (RWGS) were essentially identical. More, the surface concentration of formate, carbonate and carbonyl species was similar in each case. The presence of well-resolved IR bands allowed an unequivocal relative quantitative analysis of each species, avoiding the use of the carboxylate stretching region (1600-1200 cm(-1)). However, the quantitative analysis in the case of an isotopic study was complicated due to the overlapping of the various isotope bands, yet this problem could be overcome by integrating the high-wavenumber part of the bands. The reactivity of the surface species formed under RWGS conditions was followed under two different gaseous streams. Firstly, the reactivity of these intermediates were followed under an inert gas (i.e., At), in which case carbonates were essentially stable and less reactive than formates. Secondly, the reactivity of the same surface species was followed when switching to the corresponding C-13-labelled feed (i.e., (CO2)-C-13 + H-2), in which case carbonates were exchanged significantly faster than formates. While carbonates species have been reported as reaction intermediate under reaction conditions, the increased stability or surface poisoning by these carbonates in the absence of reaction mixture was highlighted. Ultimately, this work re-emphasises the need to use steady-state conditions if the true operando reactivity of the adsorbates and structure of the solid are to be determined. (c) 2005 Elsevier B.V. All rights reserved.