22The mean squared error (MSE) and the related normalization, the Nash-Sutcliffe efficiency (NSE

4 SAHRA (Sustainability of semi-arid hydrology and riparian areas), Global change is affecting the hydrologic response of landscapes in various ways. Understanding and predicting these effects on the water cycle are becoming increasingly critical (Jackson et al., 2001), but to date, there has been little progress in generating mechanistic relationships between climate, land use and hydrologic partitioning that can be broadly applied. Projected changes in surface temperature and precipitation dynamics will undoubtedly alter the runoff regime (Barnett et al., 2005) as well as runoff extremes (Milly et al., 2002; Dai et al., 2004). The sensitivity of annual stream flow (runoff) to changes in temperature and precipitation has been investigated empirically as well as theoretically (Arnell, 1996). Runoff sensitivity to climate change derived from the observational record has limited predictive capacity in light of non-stationarity of interdependent hydroclimatic variables and landscape features in a changing environment (Milly et al., 2008). Water balance models (Schaake, 1990; Dooge, 1992) usually consider the landscape to be invariant and their application to specific river basins relies on observations to calibrate the model parameters (Wagener, 2007). Both climate and land use are altering the landscape with concomitant changes in ecosystem structure and function (Walther et al., 2002) and regional hydrological cycles (Breshears et al., 2005). Although the hydrologic impacts of land use change imposed by humans have received considerable attention by hydrologists (e.g. Hurkmans et al., 2009), the impacts of natural large-scale vegetation shifts as a consequence of climate change are unclear (Allen and Breshears, 1998). Vegetation shifts are an important climate-ecosystem-hydrology feedback through their alteration of carbon, water and energy exchanges at the land surface (Adams et al., 2009). Although recent ecohydrological studies have focussed on understanding interactions between hydroclimatic variables and ecosystems response (e.g. Rodriguez-Iturbe and Porporato, 2004), as well as the effects of ecosystem structure on local-to-regional hydroclimate (e.g. Rinehart et al., 2008; Veatch et al., 2009), we lack a comprehensive theory of how vegetation will respond to changes in the water and energy balance of a region.Over short timescales, vegetation can respond adaptively to variations in climatic factors. Vegetation productivity, measured as net carbon uptake by the landscape or estimated from patterns of aboveground net primary production (ANPP), and growing-season actual evapotranspiration are strongly related (Webb et al., 1986). Since actual evapotranspiration typically is the largest component of many ecosystem water balances (Zhang et al., 2001), the inter-annual variability of catchment hydrologic response should be strongly related to ecosystem function and productivity. Thus, understanding vegetation response to inter-annual variability of climate and water availability should be central in any attempt t...

[1] Continental-scale water balance (WB) assessments are important for characterizing hydrologic systems and understanding regional-scale dynamics and for identifying hydroclimatic trends and systematic data biases. However, it is not clear whether existing models can reproduce the catchment dynamics observed in nature. Nor has our ability to evaluate model results kept pace with computational and data processing abilities. Consequently, methods for diagnostic model evaluation and improvement remain weak. There is a need for well-conceived, systematic strategies to guide model selection, establish data requirements, estimate parameters, and evaluate and track model performance. We examine these challenges in the context of monthly WB modeling for the conterminous United States by applying the "abcd" model to 764 catchments selected for their comprehensive coverage of hydrogeological conditions. By examining diagnostically relevant components of model error, we evaluate the details of its spatial variability across the continental United States. Model performance, parameters, and structures are found to be correlated with hydroclimatic variables. However, our results indicate a need for the conventional identification approach to be improved. Because they do not constrain models to reproduce important hydrological behaviors, reported values of NSE or r 2 performance can be misleading. Further, we must establish suitable model hypotheses with appropriate spatiotemporal scale for each hydroclimatic region. Until these issues are resolved, such models cannot reliably be used to infer the spatiotemporal dynamics of continental-scale water balance or to regionalize model structures and parameters to ungaged locations.Citation: Martinez, G. F., and H. V. Gupta (2010), Toward improved identification of hydrological models: A diagnostic evaluation of the "abcd " monthly water balance model for the conterminous United States, Water Resour. Res., 46, W08507,

Data on treatment of glucocorticoid-induced osteoporosis (GIO) in men are scarce. We performed a randomized, open-label trial in men who have taken glucocorticoids (GC) for ≥3 months, and had an areal bone mineral density (aBMD) T-score ≤ –1.5 standard deviations. Subjects received 20 μg/d teriparatide (n = 45) or 35 mg/week risedronate (n = 47) for 18 months. Primary objective was to compare lumbar spine (L1–L3) BMD measured by quantitative computed tomography (QCT). Secondary outcomes included BMD and microstructure measured by high-resolution QCT (HRQCT) at the 12th thoracic vertebra, biomechanical effects for axial compression, anterior bending, and axial torsion evaluated by finite element (FE) analysis from HRQCT data, aBMD by dual X-ray absorptiometry, biochemical markers, and safety. Computed tomography scans were performed at 0, 6, and 18 months. A mixed model repeated measures analysis was performed to compare changes from baseline between groups. Mean age was 56.3 years. Median GC dose and duration were 8.8 mg/d and 6.4 years, respectively; 39.1% of subjects had a prevalent fracture, and 32.6% received prior bisphosphonate treatment. At 18 months, trabecular BMD had significantly increased for both treatments, with significantly greater increases with teriparatide (16.3% versus 3.8%; p = 0.004). HRQCT trabecular and cortical variables significantly increased for both treatments with significantly larger improvements for teriparatide for integral and trabecular BMD and bone surface to volume ratio (BS/BV) as a microstructural measure. Vertebral strength increases at 18 months were significant in both groups (teriparatide: 26.0% to 34.0%; risedronate: 4.2% to 6.7%), with significantly higher increases in the teriparatide group for all loading modes (0.005 < p < 0.015). Adverse events were similar between groups. None of the patients on teriparatide but five (10.6%) on risedronate developed new clinical fractures (p = 0.056). In conclusion, in this 18-month trial in men with GIO, teriparatide showed larger improvements in spinal BMD, microstructure, and FE-derived strength than risedronate.

Our aim was to determine the influence of weight reduction on total (T‐) and high‐molecular weight (HMW‐) adiponectin in obese (OB) prepubertal children. Seventy OB prepubertal white patients were followed for 18 months and studied after reducing their BMI by 1 (n = 51) and 2 standard deviation scores (SDS) (n = 21) under conservative treatment, and 6 months after achieving weight loss (n = 44). Body composition dual‐energy X‐ray absorptiometry (DXA) and serum levels of T‐ and HMW‐adiponectin, resistin, leptin, leptin soluble receptor (sOB‐R), tumoral necrosis factor‐α and interleukin‐6 were determined. The control group consisted of 61 healthy prepubertal children. At diagnosis T‐adiponectin was higher (P < 0.01; confidence interval (+0.04) — (+0.15)) and HMW‐adiponectin lower (P < 0.001; confidence interval (−0.45) − (−0.21)) in OB children than in controls. A reduction in body fat increased T‐ and HMW‐adiponectin and sOB‐R (all P < 0.001) and decreased leptin (P < 0.001) and interleukin‐6 levels (P < 0.05). After 6 months of sustained weight reduction a decrease in tumoral necrosis factor‐α (P < 0.01) occurred, whereas weight recovery increased leptin (P < 0.001) and decreased T‐adiponectin (P < 0.05). HMW‐adiponectin levels negatively correlated with homeostasis model assessment (HOMA) index and BMI in the whole cohort (both P < 0.001), as did T‐adiponectin levels and HOMA index in OB patients (P < 0.01), but neither T‐ nor HMW‐adiponectin correlated with body fat content (BFC) in OB children. We conclude that the impairment of T‐ and HMW‐adiponectin levels in childhood obesity is different to that in elder OB patients, showing closer relationship with carbohydrate metabolism parameters than with BFC, but increasing their levels after weight loss and in association with metabolic improvement.

.[1] Methods to select parsimonious and hydrologically consistent model structures are useful for evaluating dominance of hydrologic processes and representativeness of data. While information criteria (appropriately constrained to obey underlying statistical assumptions) can provide a basis for evaluating appropriate model complexity, it is not sufficient to rely upon the principle of maximum likelihood (ML) alone. We suggest that one must also call upon a ''principle of hydrologic consistency,'' meaning that selected ML structures and parameter estimates must be constrained (as well as possible) to reproduce desired hydrological characteristics of the processes under investigation. This argument is demonstrated in the context of evaluating the suitability of candidate model structures for lumped water balance modeling across the continental United States, using data from 307 snow-free catchments. The models are constrained to satisfy several tests of hydrologic consistency, a flow space transformation is used to ensure better consistency with underlying statistical assumptions, and information criteria are used to evaluate model complexity relative to the data. The results clearly demonstrate that the principle of consistency provides a sensible basis for guiding selection of model structures and indicate strong spatial persistence of certain model structures across the continental United States. Further work to untangle reasons for model structure predominance can help to relate conceptual model structures to physical characteristics of the catchments, facilitating the task of prediction in ungaged basins.Citation: Martinez, G. F., and H. V. Gupta (2011), Hydrologic consistency as a basis for assessing complexity of monthly water balance models for the continental United States, Water Resour.

There is still controversy over the impact of diabetes control and duration on bone mass and growth parameters in children and adolescents with insulin-dependent diabetes mellitus (IDDM). The aim of this study was to assess bone mineral density (BMD) at axial and appendicular sites, in children with noncomplicated IDDM of recent onset, and its relation to metabolic control and auxological parameters (weight, height, and puberal stage). Fifty-five young Spanish IDDM, otherwise healthy patients (26 males, aged (SD 9.7 +/- 4.3 years) and 29 females, aged (SD 11.2 +/- 3.8 years) were studied. Duration of diabetes was 1-13.8 years. Two hundred eighty-two age-matched, healthy, Spanish children served as controls. HbA1 was assayed by high pressure liquid chromatography (HPLC) and BMD was measured using dual X-ray absorptiometry (DXA) densitometry at the spine and forearm. Results showed a Gaussian BMD distribution of patients according to sex and age, without sexual-stage differences. There was no correlation between BMD and glycated hemoglobin (average life disease or last HbA1 values) or duration of the disease; moreover, no differences in bone mass were found between <3 and >/=3 years of disease duration. Diabetes impact index (mean HbA1 x duration of disease in months) showed no significant influence of diabetes control on BMD. We could not demonstrate any impact of diabetes on BMD and growth parameters in children with IDDM of short duration.

Patients on long-term therapy do not show accelerated bone loss at the lumbar spine. Nevertheless, a considerable proportion of patients, mainly those treated with prednisone, showed densitometric osteoporosis.