Analysis of finger movement coordination during the Variable Dexterity Test and comparative activities of daily living

Background/Aims: This study aimed to analyse and compare finger coordination patterns during the performance of the Variable Dexterity Test (VDT) and comparative daily tasks. Methods: An optoelectronic system was used to record the joint angles of 10 healthy participants performing the VDT and daily tasks. Joint angles from digits 1 to 5 were cross-correlated across the tasks, providing a measure of the degree of finger movement coordination. Results: Correlation coefficients showed identifiable coordination patterns among the finger movements under analysis. Low correlation coefficients suggested the presence of independent finger movements during the performance of the selected tasks. Conclusions: Finger movement coordination patterns observed during activities of daily living are comparable with the patterns observed during performance of the Variable Dexterity Test for the three grasping patterns analysed in the stud

Влияние акустических колебаний, генерируемых при трении, на изнашивание титановых сплавов

Представлены исследования изнашивания титановых сплавов в условиях гашения акустических колебаний возникающих при трении. Показано, что акустические колебания по своему действию аналогичны дополнительной эффективной нагрузке. Гашением акустических колебаний в трибосистеме можно влиять на механизм изнашивания и снижать износ титановых сплавов

Compton Scattering from the Deuteron and Extracted Neutron Polarizabilities

Differential cross sections for Compton scattering from the deuteron were measured at MAX-lab for incident photon energies of 55 MeV and 66 MeV at nominal laboratory angles of $45^\circ$, $125^\circ$, and $135^\circ$. Tagged photons were scattered from liquid deuterium and detected in three NaI spectrometers. By comparing the data with theoretical calculations in the framework of a one-boson-exchange potential model, the sum and difference of the isospin-averaged nucleon polarizabilities, $\alpha_N + \beta_N = 17.4 \pm 3.7$ and $\alpha_N - \beta_N = 6.4 \pm 2.4$ (in units of $10^{-4}$ fm$^3$), have been determined. By combining the latter with the global-averaged value for $\alpha_p - \beta_p$ and using the predictions of the Baldin sum rule for the sum of the nucleon polarizabilities, we have obtained values for the neutron electric and magnetic polarizabilities of $\alpha_n= 8.8 \pm 2.4$(total) $\pm 3.0$(model) and $\beta_n = 6.5 \mp 2.4$(total) $\mp 3.0$(model), respectively.Comment: 4 pages, 2 figures, revtex. The text is substantially revised. The cross sections are slightly different due to improvements in the analysi

Determination of aragonite trace element distribution coefficients from speleothem calcite–aragonite transitions

The processes that govern the incorporation of (trace) elements into speleothems can often be linked to environmental changes. Although element incorporation into speleothem calcite is now reasonably well understood, current knowledge regarding trace element variability in speleothem aragonite is very limited. Of particular interest is whether trace element distribution coefficients are above or below one in order to assess the extent to which prior aragonite precipitation has affected speleothem aragonite trace element records. This study uses nine calcite-to-aragonite transitions in seven speleothems from diverse environmental settings to derive the first quantitative estimates of the distribution coefficients for several elements in speleothem aragonite: DMg(Ar) = 9.7E−5 ± 9.01E−5, DBa(Ar) = 0.91 ± 0.88, DSr(Ar) = 1.38 ± 0.53, and DU(Ar) = 6.26 ± 4.54 (1σ SD). For one speleothem from western Germany, the distribution coefficients are generally higher, which is potentially related to the very low growth rates (<11 μm/year) of this sample. In particular, DSr(Ar) appears to show a negative correlation with growth rate when growth rate is below 20 μm/year. In summary, our results demonstrate that speleothem aragonite DMg(Ar) is below one, DU(Ar) is considerably above one, and DSr(Ar) is above one or close to unity. For DBa(Ar), reaching a similar conclusion is difficult due to the relatively high uncertainty. Enhanced prior aragonite precipitation will thus result in lower U and higher Mg concentrations in speleothem aragonite, although in many cases Mg in speleothem aragonite is most likely dominated by other processes. This result suggests that U concentrations in aragonitic stalagmites could serve as a very effective proxy for palaeo-rainfall

Meson-induced correlations of nucleons in nuclear Compton scattering

The non-resonant (seagull) contribution to the nuclear Compton amplitude at low energies is strongly influenced by nucleon correlations arising from meson exchange. We study this problem in a modified Fermi gas model, where nuclear correlation functions are obtained with the help of perturbation theory. The dependence of the mesonic seagull amplitude on the nuclear radius is investigated and the influence of a realistic nuclear density on this amplitude is dicussed. We found that different form factors appear for the static part (proportional to the enhancement constant $\kappa$) of the mesonic seagull amplitude and for the parts, which contain the contribution from electromagnetic polarizabilities.Comment: 15 pages, Latex, epsf.sty, 9 eps figures

Zircon M127 - A Homogeneous Reference Material for SIMS U-Pb Geochronology Combined with Hafnium, Oxygen and, Potentially, Lithium Isotope Analysis

In this article, we document a detailed analytical characterisation of zircon M127, a homogeneous 12.7 carat gemstone from Ratnapura, Sri Lanka. Zircon M127 has TIMS-determined mean U-Pb radiogenic isotopic ratios of 0.084743 ± 0.000027 for 206Pb/238U and 0.67676 ± 0.00023 for 207Pb/235U (weighted means, 2s uncertainties). Its 206Pb/238U age of 524.36 ± 0.16 Ma (95% confidence uncertainty) is concordant within the uncertainties of decay constants. The d18O value (determined by laser fluorination) is 8.26 ± 0.06‰ VSMOW (2s), and the mean 176Hf/177Hf ratio (determined by solution ICP-MS) is 0.282396 ± 0.000004 (2s). The SIMS-determined d7Li value is -0.6 ± 0.9‰ (2s), with a mean mass fraction of 1.0 ± 0.1 µg g-1 Li (2s). Zircon M127 contains ~ 923 µg g-1 U. The moderate degree of radiation damage corresponds well with the time-integrated self-irradiation dose of 1.82 × 1018 alpha events per gram. This observation, and the (U-Th)/He age of 426 ± 7 Ma (2s), which is typical of unheated Sri Lankan zircon, enable us to exclude any thermal treatment. Zircon M127 is proposed as a reference material for the determination of zircon U-Pb ages by means of SIMS in combination with hafnium and stable isotope (oxygen and potentially also lithium) determination

Functional polymorphisms within the inflammatory pathway regulate expression of extracellular matrix components in a genetic risk dependent model for anterior cruciate ligament injuries

Objectives: To investigate the functional effect of genetic polymorphisms of the inflammatory pathway on structural extracellular matrix components (ECM) and the susceptibility to an anterior cruciate ligament (ACL) injury. Design: Laboratory study, case–control study. Methods: Eight healthy participants were genotyped for interleukin (IL)1B rs16944 C > T and IL6 rs1800795 G > C and

Evaluation of blood reservation and use for caesarean sections in a tertiary maternity unit in south western Nigeria

<p>Abstract</p> <p>Background</p> <p>Haemorrhage from obstetric causes is the most common cause of maternal mortality in the developing world. Prevention of mortality from haemorrhage will necessarily involve prompt blood transfusions among other life saving measures. There are however limited stocks of fresh or stored blood in many health care facilities in Sub Saharan Africa. Caesarean section has been identified as a common indication for blood transfusion in obstetrics practice and its performance is often delayed by non availability of blood in our centre. An evaluation of blood reservation and use at caesarean sections in a tertiary maternity unit in Lagos, south western Nigeria should therefore assist in formulating the most rational blood transfusion policies.</p> <p>Methods</p> <p>Case records of 327 patients who had elective and emergency caesarian sections at the Lagos State University Teaching Hospital between 1^stOctober and 31^stDecember 2007 were reviewed. Data pertaining to age, parity, booking status, type and indication for Caesarean section, pre- and post-operative packed cell volume, blood loss at surgery, units of blood reserved in the blood bank, unit(s) of blood transfused and duration of hospital stay was extracted and the data analysed.</p> <p>Results</p> <p>There were 1056 deliveries out of which 327 (31%) were by Caesarean section. During the study period, a total of 654 units of blood were reserved in the blood bank and subsequently made available in theatre. Out of this number, only 89 (13.6%) were transfused to 41 patients. Amongst those transfused, twenty-six (54%) were booked and 31 (75.6%) had primary caesarian section. About 81% of those transfused had emergency caesarean section. The most common indication for surgery among those transfused were placenta praevia (9 patients with 21 units of blood) and cephalo-pelvic disproportion (8 patients with 13 units).</p> <p>Conclusion</p> <p>Even though a large number of units of blood was reserved and made available in the theatre at the time of operation, majority of the patients operated did not need blood transfusion. Provision of a mini- blood bank within the obstetric unit and careful patient categorization will ensure timely availability of blood for surgery without necessarily tying down stock in the central blood bank.</p

The statistics of natural hand movements.

Humans constantly use their hands to interact with the environment and they engage spontaneously in a wide variety of manual activities during everyday life. In contrast, laboratory-based studies of hand function have used a limited range of predefined tasks. The natural movements made by the hand during everyday life have thus received little attention. Here, we developed a portable recording device that can be worn by subjects to track movements of their right hand as they go about their daily routine outside of a laboratory setting. We analyse the kinematic data using various statistical methods. Principal component analysis of the joint angular velocities showed that the first two components were highly conserved across subjects, explained 60% of the variance and were qualitatively similar to those reported in previous studies of reach-to-grasp movements. To examine the independence of the digits, we developed a measure based on the degree to which the movements of each digit could be linearly predicted from the movements of the other four digits. Our independence measure was highly correlated with results from previous studies of the hand, including the estimated size of the digit representations in primary motor cortex and other laboratory measures of digit individuation. Specifically, the thumb was found to be the most independent of the digits and the index finger was the most independent of the fingers. These results support and extend laboratory-based studies of the human hand