956 resultados para Mid-infrared lasers


Relevância:

20.00% 20.00%

Publicador:

Resumo:

BACKGROUND: There is growing evidence that regular physical activity (PA) reduces the risk of poor mental health. Less research has focused on the relationship between PA and positive wellbeing. The study aims were to assess the prospective associations between PA and optimism, in both young and mid-aged women. METHODS: 9688 young women (born 1973-1978) completed self-report surveys in 2000 (age 22 to 27), 2003, 2006, and 2009; and 11,226 mid-aged women (born 1946-1951) completed surveys in 2001 (age 50-55) 2004, 2007, and 2010, as part of the Australian Longitudinal Study on Women's Health. Generalized estimating equation models (with 3-year time lag) were used to examine the relationship between PA and optimism in both cohorts. RESULTS: In both cohorts, women reporting higher levels of PA had greater odds of reporting higher optimism over the 9-year period, (young, OR = 5.04, 95% CI: 3.85-6.59; mid-age, OR = 5.77, 95% CI: 4.76-7.00) than women who reported no PA. Odds were attenuated in adjusted models, with depression accounting for a large amount of this attenuation (young, OR = 2.00, 95% CI: 1.57-2.55; mid-age, OR = 1.64 95% CI: 1.38-1.94). CONCLUSIONS: Physical activity can promote optimism in young and mid-aged women over time, even after accounting for the negative effects of other psychosocial indicators such as depression.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Assignments of the infrared frequencies of methyl and ethyl xanthato complexes of nickel(II) have been made with the aid of normal coordinate analyses. The assignments are discussed in relation to those in related molecules.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

ABSTRACT: Infrared studies of synthetic alamethicin fragments and model peptides containing a-aminoisobutyric acid (Aib) have been carried out in solution. Tripeptides and larger fragments exhibit a strong tendency to form /3 turns, stabilized by 4 - 1 10-atom hydrogen bonds. Dipeptides show less well-defined structures, though C5 and C7 conformations are detectable. Conformational restrictions imposed by Aib residues result in these peptides populating a limited range of states. Integrated intensities of the hydrogen-bonded N-H stretching band can be used to quantitate the number of intramolecular hydrogen bonds. Predictions made from infrared data are in excellent agreement with nuclear magnetic resonance and X-ray diffraction studies. Assignments of the urethane and tertiary amide carbonyl groups in the free state have been made in model peptides. Shifts to lower frequency on hydrogen bonding are observed for the carbonyl groups. The 1-6 segment of alamethicin is shown to adopt a 310 helical structure stabilized by four intramolecular hydrogen bonds. The fragments Boc-Leu-Aib-Pro-Val-Aib-OMe (1 2-1 6) and Boc-Gly-Leu-Aib-Pro-Val-Aib-OMe (1 1-1 6) possess structures involving 4 - 1 and 5 - 1 hydrogen bonds. Supporting evidence for these structures is obtained from proton nuclear magnetic resonance studies.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The i.r. frequencies of ethylthioxanthate complexes of some transition metals have been interpreted on the basis of normal coordinate treatments of the 1:1 molecular models. The band assignments are disscussed in comparison with those in closely related xanthate molecules.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Near infrared (NIR) spectroscopy was investigated as a potential rapid method of estimating fish age from whole otoliths of Saddletail snapper (Lutjanus malabaricus). Whole otoliths from 209 Saddletail snapper were extracted and the NIR spectral characteristics were acquired over a spectral range of 800–2780 nm. Partial least-squares models (PLS) were developed from the diffuse reflectance spectra and reference-validated age estimates (based on traditional sectioned otolith increments) to predict age for independent otolith samples. Predictive models developed for a specific season and geographical location performed poorly against a different season and geographical location. However, overall PLS regression statistics for predicting a combined population incorporating both geographic location and season variables were: coefficient of determination (R2) = 0.94, root mean square error of prediction (RMSEP) = 1.54 for age estimation, indicating that Saddletail age could be predicted within 1.5 increment counts. This level of accuracy suggests the method warrants further development for Saddletail snapper and may have potential for other fish species. A rapid method of fish age estimation could have the potential to reduce greatly both costs of time and materials in the assessment and management of commercial fisheries.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Reliable age information is vital for effective fisheries management, yet age determinations are absent for many deepwater sharks as they cannot be aged using traditional methods of growth bands counts. An alternative approach to ageing using near infrared spectroscopy (NIRS) was investigated using dorsal fin spines, vertebrae and fin clips of three species of deepwater sharks. Ages were successfully estimated for the two dogfish, Squalus megalops and Squalus montalbani, and NIRS spectra were correlated with body size in the catshark, Asymbolus pallidus. Correlations between estimated-ages of the dogfish dorsal fin spines and their NIRS spectra were good, with S. megalops R2=0.82 and S. montalbani R2=0.73. NIRS spectra from S. megalops vertebrae and fin clips that have no visible growth bands were correlated with estimated-ages, with R2=0.89 and 0.76, respectively. NIRS has the capacity to non-lethally estimate ages from fin spines and fin clips, and thus could significantly reduce the numbers of sharks that need to be lethally sampled for ageing studies. The detection of ageing materials by NIRS in poorly calcified deepwater shark vertebrae could potentially enable ageing of this group of sharks that are vulnerable to exploitation.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Processing Australian hardwood plantations into rotary veneer can produce more acceptable marketable product recoveries compared to traditional processing techniques (e.g. sawmilling). Veneers resulting from processing trials from six commercially important Australian hardwood species were dominated by D-grade veneer. Defects such as encased knots, gum pockets, gum veins, surface roughness, splits, bark pockets, and decay impacted the final assigned grade. Four grading scenarios were adopted. The first included a change to the grade limitations for gum pockets and gum veins, while the second investigated the potential impact of effective pruning on grade recovery. Although both scenarios individually had a positive impact on achieving higher face grade veneer qualities, the third and fourth scenarios, which combined both, had a substantial impact, with relative veneer values increasing up to 18.2% using conservative calculations (scenario three) or up to 22.6% (scenario four) where some of the upgraded veneers were further upgraded to A-grade, which attracts superior value. The total change in veneer value was found to depend on the average billet diameter unless defects other than those relating to the scenarios (gum or knots) restricted the benefit of pruning and gum upgrading. This was the case for species prone to high levels of growth stress and related defects.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Rotational isomerism of S-methyl N-methyl dithiocarbamate (MMDTC) has been investigated by means of variable temperature proton NMR and i.r. spectroscopy. The i.r. spectra of MMDTC as neat, solution and at sub-ambient temperatures have been examined. Normal vibrational analysis of all the fundamentals of MMDTC has been carried out, the vibrational assignment has been compared with those of related secondary thioamides to note the consistency in the assignments and to obtain the pattern characteristic of the secondary thioamide vibrations.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The metal to insulator transition in the charge-transfer NiS2-xSex compound has been investigated through infrared reflectivity. Measurements performed by applying pressure to pure NiS2 (lattice contraction) and by Se alloying (lattice expansion) reveal that in both cases an anomalous metallic state is obtained. We find that optical results are not compatible with the linear Se-alloying vs pressure-scaling relation previously established through transport, thus pointing out the substantially different microscopic origin of the two transitions.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

To age sharks, the growth bands in the shark vertebrae (like the rings in a tree) or on the spines in front of each dorsal fin (which only some sharks have) are manually counted using a microscope. This is time-consuming and is only possible on dead animals. NIR spectroscopy is shown to be able to detect age in dorsal fin spines of sharks and hand-held NIR spectroscopy units could potentially be used for ageing of sharks in the field, at sea, using a hand-held unit to scan the fin spine on a live animal.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The project aimed to evaluate the innovative application of NIRS as a reliable, repeatable, and cost-effective method of ageing fish, using otoliths of Barramundi and Snapper as study species. Specific research questions included assessing how geographic and seasonal variation in otoliths affects NIRS predictive models of fish age, as well as how the NIR spectra of otoliths change in the short-term (i.e., <12 months) and long-term (i.e., historical otolith collections) and what effect this has on the predictive ability of NIRS models. The cost-effectiveness of using NIRS to supplement standard fish ageing methods was also evaluated using a hypothetical case study of Barramundi.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

IR absorption spectra of As-Se glasses have been studied over a wide range of compositions. Various two-phonon, multiphonon (combination tones) and impurity absorptions have been identified. Compositional variation of relative band intensities has been explained in terms of the chemically ordered network model.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The i.r. spectra of a primary dithiocarbamate ester namely, S-methyl dithiocarbamate (SMDTC) and its N-dideuterated compound have been measured between 4000 and 30 cm−1. Spectra in solution and at liquid nitrogen temperature have also been obtained. Assignment of all the fundamentals has been proposed and supported from a full normal coordinate analysis. The band assignments for SMDTC have been compared with those of related molecules and the characteristic bands of primary thioamides are derived. Conformational flexibility of SMDTC has been examined by i.r. and proton NMR spectroscopy. The hindered rotation around the C---N bond has been studied by a complete line shape analysis. The magnitude of ---NH2 and ---CH3 torsional barriers is also estimated from vibrational frequencies and force constants.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Family trees of the descendants of the Wieruszowski and of the Apt families from the mid 1700’s to the late 1900’s, from family sources and from other places.