Temporal Rate Of Change Research Articles

Genetic variation in MTNR1B is associated with gestational diabetes mellitus and contributes only to the absolute level of beta cell compensation in Mexican Americans.

MTNR1B is a type 2 diabetes susceptibility locus associated with cross-sectional measures of insulin secretion. We hypothesised that variation in MTNR1B contributes to the absolute level of a diabetes-related trait, temporal rate of change in that trait, or both. We tested rs10830963 for association with cross-sectional diabetes-related traits in up to 1,383 individuals or with rate of change in the same phenotypes over a 3-5 year follow-up in up to 374 individuals from the family-based BetaGene study of Mexican Americans. rs10830963 was associated cross-sectionally with fasting glucose (p = 0.0069), acute insulin response (AIR; p = 0.0013), disposition index (p = 0.00078), glucose effectiveness (p = 0.018) and gestational diabetes mellitus (OR 1.48; p = 0.012), but not with OGTT 30 min Δinsulin (the difference between the 30 min and fasting plasma insulin concentration) or 30 min insulin-based disposition index. rs10830963 was also associated with rate of change in fasting glucose (p = 0.043), OGTT 30 min Δinsulin (p = 0.01) and AIR (p = 0.037). There was no evidence for an association with the rate of change in beta cell compensation for insulin resistance. We conclude that variation in MTNR1B contributes to the absolute level of insulin secretion but not to differences in the temporal rate of change in insulin secretion. The observed association with the rate of change in insulin secretion reflects the natural physiological response to changes in underlying insulin sensitivity and is not a direct effect of the variant.

Geostrophic and ageostrophic circulation of a shallow anticyclonic eddy off Cape Bojador

AbstractA shallow mesoscale anticyclonic eddy, observed south of the Canary Islands with satellite altimetry, has been intensively studied with multiparametric sampling. Hydrographic data from a CTD installed on an undulating Nu‐shuttle platform reveal the presence of a mesoscale anticyclonic eddy of ∼125 km diameter. The difference in sea level anomaly (SLA) between the interior and the edge of the eddy, as determined from altimetry, is ∼15 cm, which compares well with the maximum dynamic height differences as inferred using a very shallow reference level (130 m). Further, the associated surface geostrophic velocities, of about 35 cm s−1 in the northeast and southwest edges of the eddy, are in good agreement with direct velocity measurements from the ship. Deep rosette‐CTD casts confirm that the structure is a shallow eddy extending no deeper than 250 m before the fusion with another anticyclone. The SLA‐tendency (temporal rate of change of sea surface height) indicates a clear northwestward migration during the two first weeks of November 2008. Applying an eddy SSH‐based tracker, the eddy's velocity propagation is estimated as 4 km d−1. Use of the QG‐Omega equation diagnoses maximum downward/upward velocities of about ±2 m d−1. The instability of the Canary coastal jet appears to be the mechanism responsible for the generation of the shallow anticyclonic eddy.

Non-reflective inlet conditions for the calculation of unsteady turbulent compressible flows at low Mach number

For the unsteady simulation of compressible subsonic flows (Large Eddy Simulation or Direct Numerical Simulation), the proper handling of the inlet boundary is a challenging task. Indeed, inflow generation through imposition of the velocity may lead to a non-physical reflection of the upstream acoustic waves. In the present contribution, a method that allows both filtering of these waves and proper imposition of the required variables is proposed. This method is based on identification of the roles of the temporal rate of change of wave amplitudes at the inlet in the low Mach number regime. The formulation obtained is tested numerically on unsteady one-dimensional flows at low Mach number for which the unsteady inlet velocity signal is purely harmonic or harmonic with the superimposition of synthetic turbulence.

A study on effects of temporally varying/ fluctuating noises on statistical profiles measured by means of PLIF method (Development of prediction formulas of the effects, and validation by high-Sc-number scalar mixing layer in grid turbulence)

In planar laser induced fluorescence (PLIF) measurement, temporally varying and fluctuating noises affect measured statistical profiles, significantly. In this study, the former φ is caused by a ratio of temporally varying quantum yield φ between measurement and reference images, and the latter sβI is mainly due to temporal fluctuations of a ratio of camera sensitively β and a ratio of incident laser I to excite a fluorescent dye, where sβI ≡ βI - 1. These noises can significantly affect statistical profiles of fluctuating concentration field. The aim of this study is to develop predictive formulas for the effects on fundamental statistical profiles. The effects of φ and sβI are reconstructed to mean of φ, αT/2, mean of sβI, SβI and intensity of fluctuation of sβI, <e2>, where α is rate of temporal change of φ, T is required time of the experiment, SβI = <sβI>, e = sβI, sβI = SβI + sβI and <> denotes ensemble average. Then, we show a series of the formulas to predict the effects on mean scalar, intensity of scalar fluctuation, 3rd-order statistics and 4th-order statistics of scalar fluctuation. The predictive formulas are validated by using experimental results of high-Sc-number scalar mixing layer in grid-generated turbulence measured by PLIF method, where the mesh Reynolds number was 2,500 and the Schmidt number was about 2,100, respectively. The effects of <e2> is analytically found to be the most significant among αT, SβI and <e2> by expanding the predictive formulas. In fact, the profile of <c2> is significantly affected by variation of <e2>. The predictive formulas can be used as formulas to correct the profiles when given values of the three parameter are appropriate.

Cellular Sensory Mechanisms for Detecting Specific Fold-Changes in Extracellular Cues

Cellular sensory systems often respond not to the absolute levels of inputs but to the fold-changes in inputs. Such a property is called fold-change detection (FCD) and is important for accurately sensing dynamic changes in environmental signals in the presence of fluctuations in their absolute levels. Previous studies defined FCD as input-scale invariance and proposed several biochemical models that achieve such a condition. Here, we prove that the previous FCD models can be approximated by a log-differentiator. Although the log-differentiator satisfies the input-scale invariance requirement, its response amplitude and response duration strongly depend on the input timescale. This creates limitations in the specificity and repeatability of detecting fold-changes in inputs. Nevertheless, FCD with specificity and repeatability by cells has been reported in the context of Drosophila wing development. Motivated by this fact and by extending previous FCD models, we here propose two possible mechanisms to achieve FCD with specificity and repeatability. One is the integrate-and-fire type: a system integrates the rate of temporal change in input and makes a response when the integrated value reaches a constant threshold, and this is followed by the reset of the integrated value. The other is the dynamic threshold type: a system response occurs when the input level reaches a threshold, whose value is multiplied by a certain constant after each response. These two mechanisms can be implemented biochemically by appropriately combining feed-forward and feedback loops. The main difference between the two models is their memory of input history; we discuss possible ways to distinguish between the two models experimentally.

Effect of numerical diffusion on the water mass transformation in eddy-resolving models

This study investigates the effect of numerical diffusion associated with advection schemes on water mass transformation in an eddy-resolving model. The effect of numerical diffusion is evaluated as a residual between the total water mass transformation and the explicit water mass transformation: the former is calculated as the sum of meridional streamfunction and the temporal change rate of an isopycnal surface depth, and the latter is directly calculated with the use of the tendency equation of density. This method is used for investigating a dependency of numerical diffusion on explicit diffusivity. It is found that idealized channel experiments are categorized into three regimes according to a magnitude of explicit diffusivity: numerical diffusion, transitional, and explicit diffusion regimes. The numerical diffusion regime is defined as the regime where explicit diffusion changes do not significantly impact the solution. The magnitude of numerical diffusion is independent of the explicit diffusivity there. In the transitional regime, explicit (numerical) diffusion works more (less) with higher explicit diffusivity. Explicit and numerical diffusions are comparably important there. The explicit diffusion becomes significantly large and the numerical diffusion is almost negligible in the explicit diffusion regime. The total diffusion effect on water mass transformation there is considerably larger than those in the two other regimes.Two experiments are conducted with a Southern Ocean model under a realistic configuration. These belong to the numerical diffusion and transitional regimes. The model becomes a little too diffusive in the latter experiment. This result and results of channel experiments indicate that it is not an adequate option for a realistic Southern Ocean simulation that we adopt a diffusion coefficient in the explicit diffusion regime in order to reduce levels of numerical diffusion. It indicates that numerical diffusion is inevitable for eddy-resolving models with horizontal resolution around 0.1° and we must adequately evaluate its effect on model results when analyzing outputs of such high resolution models. The method proposed in the current study for assessing numerical diffusion will be useful for investigating an eddying ocean with numerical models.

Retention and remobilization of colloids during steady-state and transient two-phase flow

[1] In this work, we study colloid transport through a porous medium under steady-state and transient two-phase flow conditions. The porous medium was a PDMS micromodel and the immiscible fluids were water and fluorinert-FC43. Given that the micromodel was hydrophobic, fluorinert was the wetting phase, and water was the nonwetting phase. We used hydrophilic fluorescent microspheres (dispersed in water) with mean diameter of 300 nm. We directly observed colloid movement and fluids distribution within pores of the micromodel using a confocal laser scanning microscope. We also obtained concentration breakthrough curves by measuring the fluorescence intensity in the outlet of the micromodel. The breakthrough curves showed that, under steady-state flow at different water saturations, more colloids were retained at lower saturations. Our visualization results suggested that the enhanced attachment was due to the retention of colloids onto fluorinert-water interfaces (FWIs) and fluorinert-water-solid contact lines (FWSCs). At the end of a steady-state two-phase flow experiment, we changed the micromodel saturation by injecting either water (drainage) or fluorinert (imbibition). We found remobilization of colloids during imbibition events, but no remobilization was observed during drainage. Visualization showed that colloids deposited on solid-water interfaces (SWIs) were dislodged by moving FWSCs during imbibition. We simulated breakthrough curves by modeling colloids interactions with SWIs and FWIs separately. Remobilization of colloids attached to SWI was modeled as a first-order kinetic process and the rate coefficient was assumed proportional to temporal rate of change of saturation. Colloids attachment to and detachment from FWIs were modeled as an equilibrium process. Generally, good agreements between experimental results and simulation were obtained. This is the first study of colloid transport in two-phase flow, where pore-scale visualization, breakthrough concentration measurement, and modeling of results are combined.

Quantitative Susceptibility Mapping of Multiple Sclerosis Lesions at Various Ages

To assess multiple sclerosis (MS) lesions at various ages by using quantitative susceptibility mapping (QSM) and conventional magnetic resonance (MR) imaging. Retrospectively selected were 32 clinically confirmed MS patients (nine men and 23 women; 39.3 years ± 10.9) who underwent two MR examinations (interval, 0.43 years ± 0.16) with three-dimensional gradient-echo sequence from August 2011 to August 2012. To estimate the ages of MS lesions, MR examinations performed 0.3-10.6 years before study examinations were studied. Hyperintensity on T2-weighted images was used to define MS lesions. QSM images were reconstructed from gradient-echo data. Susceptibility of MS lesions and temporal rates of change were obtained from QSM images. Lesion susceptibilities were analyzed by t test with intracluster correlation adjustment and Bonferroni correction in multiple comparisons. MR imaging of 32 patients depicted 598 MS lesions, of which 162 lesions (27.1%) in 23 patients were age measurable and six (1.0%) were only visible at QSM. The susceptibilities relative to normal-appearing white matter (NAWM) were 0.53 ppb ± 3.34 for acute enhanced lesions, 38.43 ppb ± 13.0 (positive; P < .01) for early to intermediately aged nonenhanced lesions, and 4.67 ppb ± 3.18 for chronic nonenhanced lesions. Temporal rates of susceptibility changes relative to cerebrospinal fluid were 12.49 ppb/month ± 3.15 for acute enhanced lesions, 1.27 ppb/month ± 2.31 for early to intermediately aged nonenhanced lesions, and -0.004 ppb/month ± 0 for chronic nonenhanced lesions. Magnetic susceptibility of MS lesions increased rapidly as it changed from enhanced to nonenhanced, it attained a high susceptibility value relative to NAWM during its initial few years (approximately 4 years), and it gradually dissipated back to susceptibility similar to that of NAWM as it aged, which may provide new insight into pathophysiologic features of MS lesions. Online supplemental material is available for this article.

KINEMATICS OF THE ORION TRAPEZIUM BASED ON DIFFRACTO-ASTROMETRY AND HISTORICAL DATA

Using the novel Diffracto-Astrometry technique, we analyze 44 Hubble Space Telescope Wide Field Planetary Camera 2 images of the Orion Trapezium (OT) taken over a span of 12 yr (1995-2007). We measure the relative positions of the six brighter OT components (A-F) and supplement these results with measurements of the relative separations and position angles taken from the literature, thus extending our analysis time base to ~200 yr. For every pair of components we find the relative rate of separation as well as the temporal rate of change of their position angles, which enable us to determine the relative kinematics of the system. Component E shows a velocity larger than the OT's escape velocity, thus confirming that it is escaping from the gravitational pull of this system.

Intrinsic time dependence in the diversity–invasibility relationship

Contrasting patterns in the diversity-invasibility relationship have intrigued ecologists for many years, and are now known as the "invasion paradox." Experiments usually detect negative relationships, while field surveys find them to be positive. It is widely believed that the paradox is driven by differences in spatial scale, but this is challenged by field surveys that find positive relationships at all spatial scales. If factors that determine invasion dynamics change during the invasion process, the paradox may be partially driven by differences in temporal scale. Here we used simulation (cellular automata) models to explore the generality of temporal change in the diversity-invasibility relationship. The probability of invaders colonizing an area was inversely related to the density of natives, creating a negative native-exotic correlation when invaders first arrived. Over time, native and exotic populations were both shaped by the same post-introduction processes (disturbance, dispersal, and recolonization), shifting their correlation to positive. The rate of temporal change in the diversity-invasibility relationship was mainly dependent upon the fecundity of invaders. Greater fecundity meant that invaders spread through the landscape faster and were subject to post-introduction processes sooner. We propose a unified conceptual model where the diversity-invasiblity relationship is a function of both spatial and temporal scales.

Fluctuations of the vortex line density in turbulent flows of quantum fluids

We present an analytical study of fluctuations of the vortex line density (VLD) $\ensuremath{\langle}\ensuremath{\delta}\mathcal{L}(\ensuremath{\omega})\ensuremath{\delta}\mathcal{L}(\ensuremath{-}\ensuremath{\omega})\ensuremath{\rangle}$ in turbulent flows of quantum fluids. Two cases are considered. The first is the counterflowing (Vinen) turbulence, where the vortex lines are disordered, and the evolution of quantity $\mathcal{L}(t)$ obeys the Vinen equation. The second case is the fluctuations of the VLD in a single vortex bundle, which develops inside the domain of the concentrated normal-fluid vorticity. The dynamics of the vortex bundle is described by the Hall-Vinen-Bekarevich-Khalatnikov (HVBK) equations. The latter case is of special interest, because the set of the quantum vortex bundles is believed to mimic classical hydrodynamic turbulence. In steady states the VLD is related to the normal velocity as $\mathcal{L}={(\ensuremath{\rho}\ensuremath{\gamma}/{\ensuremath{\rho}}_{s})}^{2}{v}_{n}^{2}$ for the Vinen case. In the vortex bundle case, which appears inside the domain of a concentrated vorticity of normal fluid, the stationary quantity $\mathcal{L}$ can be found from the matching of velocities and is described by $\mathcal{L}=|\ensuremath{\nabla}\ifmmode\times\else\texttimes\fi{}{\mathbf{v}}_{n}|/\ensuremath{\kappa}$. In nonstationary situations, and particularly in the fluctuating turbulent flow, there is a retardation between the instantaneous value of the normal velocity and the quantity $\mathcal{L}$. This retardation tends to decrease in accordance with the inner dynamics, which has a relaxation character. In both cases, the relaxation dynamics of the VLD is related to fluctuations of the relative velocity. However, for the Vinen case the rate of temporal change for $\mathcal{L}(t)$ is directly dependent upon $\ensuremath{\delta}{\mathbf{v}}_{ns}$, whereas for HVBK dynamics it depends on $\ensuremath{\nabla}\ifmmode\times\else\texttimes\fi{}\ensuremath{\delta}{\mathbf{v}}_{ns}$. Therefore, for the disordered case the spectrum $\ensuremath{\langle}\ensuremath{\delta}\mathcal{L}(\ensuremath{\omega})\ensuremath{\delta}\mathcal{L}(\ensuremath{-}\ensuremath{\omega})\ensuremath{\rangle}$ coincides with the spectrum ${\ensuremath{\omega}}^{\ensuremath{-}5/3}$. In the case of the bundle arrangement, the spectrum of the VLD varies (at different temperatures) from ${\ensuremath{\omega}}^{1/3}$ to ${\ensuremath{\omega}}^{\ensuremath{-}5/3}$ dependencies. This conclusion may serve as a basis for the experimental determination of what kind of turbulence is implemented in different types of generation.

A study on the annual runoff change and its relationship with water and soil conservation practices and climate change in the middle Yellow River basin

Based on the long-term hydrological and meteorological series, DEM, soil database and documents of soil conservation measures of the middle Yellow River, investigations are made on the spatial and temporal changes of runoff and the impact of 11 factors, which include rainfall, temperature, terrain slope, drainage density, gravel, sand, silt, and organic carbon content in soil, water consumption, and soil conservation measures. The results show that the total runoff generated from the middle Yellow River had a decreasing trend in the past 60 years, with two abrupt falls around the years 1971 and 1991. In the spatial dimension, runoff modulus grew from the north to the south and from the west to the east, and the largest gradient of spatial change of runoff modulus happened during the period of 1956–1970 before the first falls of the total runoff. In the period 1954–2009, the average annual rate of temporal change of runoff modulus increased acceleratedly outward from the northwest of the middle Yellow River with a concentric ring pattern. Correlation analysis of runoff modulus with potential influencing factors in the spatial perspective reveals that the spatial distribution of the runoff modulus is principally the results of the regional variation of natural conditions. The results of the correlation analysis of the temporal series of runoff coefficient and influencing factors suggest that climate change, hydraulic engineering and soil conservation measures, were all the major causes of runoff reducing in the second half of the last century in the middle Yellow River. For the whole middle Yellow River, climate change contributed over 40% of the runoff deviations in the 1960s, 1970s and 1990s, while water consumption induced also over 40% runoff reduction in the 1960s, 1970s and 1980s. The runoff reduction due to hydraulic engineering was about 2–3 times of that caused by soil conservation measures, and both of them increased continuously from the 1960s to the 1980s, and kept at a higher level in the 1990s. The contribution of different causes to runoff deviation was variable in different drainage areas. Generally, in the semi-arid areas climate change played a decreasing role in runoff reduction comparing with other causes, while in the semi-humid areas it induced a higher and more variable proportion of runoff deviation according to the decade means.

Trends in ozone concentrations in the Iberian Peninsula by quantile regression and clustering

In this paper, 10-years of ozone (O3) hourly concentrations collected over the period 2000–2009 in the Iberian Peninsula (IP) are analyzed using records from 11 background sites. All the selected monitoring stations present an acquisition efficiency above 85%. The changes in surface ozone over the Iberian Peninsula are examined by means of quantile regression, which allows to analyse the trends not only in the mean but in the overall data distribution. In addition, the ozone hourly concentrations records are clustered on the basis of their resulting distributions.The analysis showed that high altitude stations (>900 m) have higher background O3 concentrations (∼80 μg m−3). The same magnitude of background O3 concentrations is found in stations near the Mediterranean Sea. On the other hand, the rural stations near the Atlantic coast present lower background values (∼50–60 μg m−3) than those of Mediterranean influence. The two sub-urban stations exhibit the lowest background concentrations (∼45 μg m−3). The results of the quantile regression show a very distinct behaviour of the data distribution, the slopes for a fixed quantile are not the same over IP, reflecting the spatial dependence of O3 trends. Hence the rate of temporal change is not the same for all parts of the data distribution, as implicitly assumed in ordinary regression. The lower quantile (percentile 5) presents higher rates of change than the middle (percentile 50) and the upper quantile (percentile 95). The clustering procedure reveals what has been already detected in the quantile regression. The station with highest rates of decrease on the O3 concentrations (easternmost station of IP) is isolated and then other clusters are formed among the moderately positive/negative O3 trends around the IP. The clustering procedure highlighted that the largest trends are found for the lower ozone O3 values, with largest negative trend at the easternmost station of IP, and also in northern and mainland stations, and an opposite behaviour, with positive O3 trends, is observed at the Atlantic coast stations.

Ice flux divergence anomalies on 79north Glacier, Greenland

The ice flux divergence of a glacier is an important quantity to examine because it determines the rate of temporal change of its thickness. Here, we combine high‐resolution ice surface velocity observations of Nioghalvfjerdsfjorden (79north) Glacier, a major outlet glacier in north Greenland, with a dense grid of ice thickness data collected with an airborne radar sounder in 1998, to examine its ice flux divergence. We detect large variations, up to 100 m/yr, in flux divergence on grounded ice that are incompatible with what we know of the glacier surface mass balance, basal mass balance and thinning rate. We examine the hypothesis that these anomalies are due to the three‐dimensional flow of ice around and atop bumps and hollows in basal topography by comparing the flux divergence of three‐dimensional numerical models with its surface equivalent. We find that three‐dimensional effects have only a small contribution to the observed anomalies. On the other hand, if we degrade the spatial resolution of the data to 10 km the anomalies disappear. Further analysis shows that the source of the anomalies is not the ice velocity data but the interpolation of multiple tracks of ice thickness data onto a regular grid using a scheme (here block kriging) that does not conserve mass or ice flux. This problem is not unique to 79north Glacier but is common to all conventional ice thickness surveys of glaciers and ice sheets; and fundamentally limits the application of ice thickness grids to high‐resolution numerical modeling of glacier flow.

Cyclic energy harvesting from pyroelectric materials

A method of continuously harvesting energy from pyroelectric materials is demonstrated using an innovative cyclic heating scheme. In traditional pyroelectric energy harvesting methods, static heating sources are used, and most of the available energy has to be harvested at once. A cyclic heating system is developed such that the temperature varies between hot and cold regions. Although the energy harvested during each period of the heating cycle is small, the accumulated total energy over time may exceed traditional methods. Three materials are studied: a commonly available soft lead zirconate titanate (PZT), a pre-stressed PZT composite, and single-crystal PMN-30PT. Radiation heating and natural cooling are used such that, at smaller cyclic frequencies, the temporal rate of change in temperature is large enough to produce high power densities. The maximum power density of 8.64 μW/cm3 is generated with a PMN-30PT single crystal at an angular velocity of 0.64 rad/s with a rate of 8.5°C/s. The pre-stressed PZT composite generated a power density of 6.31 μW/cm(3), which is 40% larger than the density of 4.48 μW/cm3 obtained from standard PZT.

Hemodynamic Studies of Intracranial Dural Arteriovenous Fistulas Using Arterial Spin-Labeling MR Imaging

Arterial spin-labeling (ASL) magnetic resonance imaging (MRI) enables non-invasive acquisition of the brain perfusion information in cerebrovascular disease. We investigated hemodynamic changes in intracranial dural arteriovenous fistulas (DAVFs) using ASL-MRI. ASL-MRI by a Q2TIPS sequence on a 3.0-Tesla MRI was performed for three patients with Cognard's IIa+b type of DAVFs before and after treatment. Perfusion images obtained by ASL-MRI (ASL images) before treatment were visually compared with those by single-photon emission computed tomography images (SPECT images). Increasing rates of temporal changes of regional perfusion values in ASL images (ASL values) before and after treatment were also calculated. In all three patients, ASL images before treatment demonstrated high perfusion in regions around the shunting areas, where normal or low perfusion were detected on SPECT images; thus, ASL images might have demonstrated the abundant arterial shunting flow via the fistulas. On days eight to 20 after treatment, ASL values around the shunt areas remained the same or decreased, and those in the regions other than the shunt areas increased in all three patients. This might have been due to a combination of the following: a decrease in shunt flow volume, an amelioration of venous congestion, and a sustained an upward shift in the autoregulation of the brain perfusion pressure. All regional ASL values decreased on days 112 and 120 after treatment in two patients, which possibly reflects a reduction in the upward shift in autoregulation. ASL-MRI might be useful for identifying the hemodynamic behavior of DAVFs before and after treatment.

In-situ monitoring of the time evolution of the effective thermal conductivity of snow

Abstract We report on a 3-month long time series of in-situ measurements of the effective thermal conductivity ( k eff ) of snow at 6 heights in an Alpine snowpack in the Mont-Blanc mountain range, France, at an altitude of 2400 m. Measurements were carried out automatically every 2 days using heated-needle probes embedded in the snowpack. The experimental procedure used is presented in detail and demonstrates the applicability of single heated-needle probes for the evaluation of k eff in snow, both for long-term measurements within the snowpack and occasional use in the field. Results based on 139 automatically collected data show k eff values ranging between 0.04 and 0.35 W m − 1 K − 1 , and a consistent pattern of effective thermal conductivity increase throughout the measurements campaign. The temporal rate of change of k eff varies up to 0.01 W m − 1 K − 1 day − 1 , with maximum values just after snowfall.

Measuring evolutionary responses to global warming: cautionary lessons fromDrosophila

Abstract. 1. Understanding evolutionary responses to global climate warming can be dauntingly complex. But, primarily, it requires careful quantification of rates of temporal change of biomonitors.2. Long‐term biomonitoring programs capitalize on traits for which there already exist retrospective measurements. Those programs are thus faced with the decision as to the appropriate time to update historical records, especially in species whose gene frequencies cycle over the successive seasons. In these cases, the time during the year at which descendant populations are sampled needs to take into account effects of the lengthening growing season that can impose direct selection on specific genotypes and, concomitantly, indirect selection on photoperiodic response.3. Standardising new and past collections by calendar date can lead to an overestimation of the magnitude of long‐term responses to global warming; standardising by equivalent seasonal temperature conditions can lead to an underestimation of the magnitude of long‐term responses to global warming.4. The results of a recent monitoring study withDrosophilaindicate that caution should be exercised in how the updating of historical records is used to quantify evolutionary responses to global warming.

A Multivariate Examination of Temporal Changes in Berg Balance Scale Items for Patients With ASIA Impairment Scale C and D Spinal Cord Injuries

Datta S, Lorenz DJ, Morrison S, Ardolino E, Harkema SJ. A multivariate examination of temporal changes in Berg Balance Scale items for patients with ASIA Impairment Scale C and D spinal cord injuries. Objective To provide a multivariate examination of the Berg Balance Scale (BBS) in patients with spinal cord injury (SCI) as a first step in developing a balance tool for the SCI population. Design Observational cohort. Setting The NeuroRecovery Network (NRN), a specialized network of treatment centers providing standardized, activity-based therapy for patients with SCI. Participants Patients (N=97) with American Spinal Injury Association Impairment Scale C or D SCI who were enrolled in the NRN between March 1, 2005, and June 12, 2007. Interventions All enrolled patients received 3 to 5 locomotor training sessions a week, according to NRN protocol, and were periodically evaluated for progress on functional outcome measurements. Main Outcome Measures Scores on the items of the BBS, six-minute walk test distances, ten-meter walk test speeds, and scores on the SCI Functional Ambulation Index. Temporal rates of change of the BBS items were examined with a principal components and correlation analysis. Results The first principal component accounted for nearly half of the overall variability in the BBS, correlated well with rates of change in functional mobility measures, and had good stability in its composition as verified by a resampling analysis. Further analysis showed that the composition of the first principal component varied with the patient's level of recovery. Conclusions The BBS captures a significant amount of information about balance recovery in persons with SCI and may be a good foundation for a balance tool. However, the utility of BBS items may be dependent on a patient's level of recovery. A dynamic balance instrument for the SCI population may be needed.

Constraints on 87 Sr/ 86 Sr of Late Ediacaran seawater: insight from Siberian high-Sr limestones

Abstract: In SE Siberia, carbonate formations with δ 13 C carb values ranging between −12‰ and −7‰ (V-PDB) and Sr concentrations of up to 2.5% occupy an area of 40 000 km 2 . Several successions exceed 1000 m in thickness and represent the world's largest known exposures of sedimentary carbonates exhibiting extreme depletion in 13 C. The carbonates were deposited on a carbonate platform evolving from a mixed carbonate–siliciclastic ramp to a carbonate ramp, and then from a peritidal rimmed shelf to a deep-water open shelf. All sequences reveal a facies-independent, upward rise in marine δ 13 C carb from −12‰ to −7‰. The trend and magnitude of the values mimic those that are characteristic of the 600–550 Ma Shuram–Wonoka isotope event. A coincident stratigraphic rise in 87 Sr/ 86 Sr from 0.70802 to 0.70862 in several sections of limestones, containing 4400 μg g −1 Sr on average, is considered to be by far the best available constraint on a temporal variation of seawater isotopic composition through the Late Ediacaran. If the greatest temporal rate of change in seawater 87 Sr/ 86 Sr observed in the Cenozoic is applied to the Siberian sections, the calculated minimum duration for the Suram–Wonoka event is 10 Ma. Supplementary material: XRF and ICP-AES analysis, C, O and Sr isotopic data are available at http://www.geolsoc.org.uk/SUP18324 .