We have seen the emergence of three major innovations in the econometrics of structural change in the past fifteen years: (1) tests for a structural break of unknown timing; (2) estimation of the ...timing of a structural break; and (3) tests to distinguish unit roots from broken time trends. These three innovations have dramatically altered the face of applied time series econometrics. In this paper, we review these three innovations, and illustrate their application through an empirical assessment of U.S. labor productivity in the manufacturing/durables sector.
Atlantic hurricane season length is important for emergency management preparation, motivating the need to understand its variability and change. We investigated the influence of ocean variability on ...Atlantic hurricane season length in observations and a future climate simulated by the Energy Exascale Earth System Model (E3SM). We found that multiple factors influence hurricane season length, through their influence on season start and end. Warm western subtropical Atlantic sea‐surface temperature anomalies (SSTAs) during boreal spring (before the official hurricane season start) drive early starts to the hurricane season, and vice versa for cool SSTAs. Meanwhile, La Niña in autumn (before the official hurricane season end) drives late ends to the hurricane season, and vice versa for El Niño. E3SM projects a 27‐day increase in future Atlantic hurricane season length given La Niña and warm northern tropical Atlantic SSTAs. This research documents sources of predictability for Atlantic hurricane season length.
Plain Language Summary
Atlantic hurricane season length is important for emergency management preparation, motivating the need to understand its variability and change. We investigated the influence of ocean variability on Atlantic hurricane season length in historical observations and a future climate simulated by a global climate model. We found that multiple factors influence Atlantic hurricane season length, through their influence on season start and end. Warm sea‐surface temperature anomalies (SSTAs) in the western subtropical Atlantic during boreal spring (before the official hurricane season start) drive early starts to the hurricane season, and vice versa for cool SSTAs. Meanwhile, La Niña events in autumn (before the official hurricane season ends) drive late ends to the hurricane season, and vice versa for El Niño. The global model projects a 27–41‐day increase in future Atlantic hurricane season length. This research documents sources of predictability for Atlantic hurricane season length.
Key Points
Multiple oceanic factors influence Atlantic hurricane season length, by influencing the first and last Tropical Storm of the season
A warm western subtropical Atlantic ocean in boreal spring drives early hurricane season starts; La Niña in autumn drives late season ends
Future Atlantic hurricane season length increases by 27 days in Energy Exascale Earth System Model simulations given La Niña and a positive Atlantic Meridional Mode
The vasculature is a dynamic environment in which blood platelets constantly survey the endothelium for sites of vessel damage. The formation of a mechanically coherent hemostatic plug to prevent ...blood loss relies on a coordinated series of ligand-receptor interactions governing the recruitment, activation, and aggregation of platelets. The physical biology of each step is distinct in that the recruitment of platelets depends on the mechanosensing of the platelet receptor glycoprotein Ib for the adhesive protein von Willebrand factor, whereas platelet activation and aggregation are responsive to the mechanical forces sensed at adhesive junctions between platelets and at the platelet-matrix interface. Herein we take a biophysical perspective to discuss the current understanding of platelet mechanotransduction as well as the measurement techniques used to quantify the physical biology of platelets in the context of thrombus formation under flow.
Abstract Objective To summarize the published effects of systemic glucocorticoid therapy on bone mineral density (BMD) and fractures in children. Methods We performed a systematic review and ...meta-analysis of existing literature, using Medline, CINAHL, and Cochrane databases to identify studies of BMD or fractures in children ≤18 years taking systemic glucocorticoid therapy. We excluded studies of inhaled glucocorticoids, chemotherapy, and organ transplantation. Two authors reviewed abstracts for inclusion, read full-text articles to extract data, and rated each study using the Downs–Black scale. Results A total of 16 studies met eligibility criteria, including 10 BMD (287 children) and six fracture (37,819 children) studies. Spine BMD was significantly lower (−0.18; 95% CI = −0.25; −0.10 g/cm2 ) in children taking glucocorticoid therapy, compared to age- and gender-matched healthy controls. Spine BMD was also lower (−0.14; 95% CI = −0.27; 0.00 g/cm2 ) in children taking glucocorticoids, compared to children with the same disease not taking glucocorticoids. Incident clinical fracture rates varied from 2% to 33%. Morphometric vertebral fracture incidence ranged from 6% to 10%, and prevalence was 29–45%. Conclusion Published data suggest that children treated with glucocorticoid therapy have lower spine BMD compared to healthy children. Whether children receiving glucocorticoid therapy have lower spine BMD compared to children with milder disease not requiring such therapy is not certain. Clinical and morphometric vertebral fractures are common, although only one study assessed fracture rates in healthy controls. Additional well-designed, prospective studies are needed to evaluate the skeletal effects of glucocorticoid therapy in children.
Transfer entropy (TE) is an information-theoretic measure which has received recent attention in neuroscience for its potential to identify effective connectivity between neurons. Calculating TE for ...large ensembles of spiking neurons is computationally intensive, and has caused most investigators to probe neural interactions at only a single time delay and at a message length of only a single time bin. This is problematic, as synaptic delays between cortical neurons, for example, range from one to tens of milliseconds. In addition, neurons produce bursts of spikes spanning multiple time bins. To address these issues, here we introduce a free software package that allows TE to be measured at multiple delays and message lengths. To assess performance, we applied these extensions of TE to a spiking cortical network model (Izhikevich, 2006) with known connectivity and a range of synaptic delays. For comparison, we also investigated single-delay TE, at a message length of one bin (D1TE), and cross-correlation (CC) methods. We found that D1TE could identify 36% of true connections when evaluated at a false positive rate of 1%. For extended versions of TE, this dramatically improved to 73% of true connections. In addition, the connections correctly identified by extended versions of TE accounted for 85% of the total synaptic weight in the network. Cross correlation methods generally performed more poorly than extended TE, but were useful when data length was short. A computational performance analysis demonstrated that the algorithm for extended TE, when used on currently available desktop computers, could extract effective connectivity from 1 hr recordings containing 200 neurons in ∼5 min. We conclude that extending TE to multiple delays and message lengths improves its ability to assess effective connectivity between spiking neurons. These extensions to TE soon could become practical tools for experimentalists who record hundreds of spiking neurons.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
This systematic review aimed at evaluating the efficacy, acceptability and safety of guided imagery/hypnosis (GI/H) in fibromyalgia.
Cochrane Library, MEDLINE, PsycINFO and SCOPUS were screened ...through February 2016. Randomized controlled trials (RCTs) comparing GI/H with controls were analysed. Primary outcomes were ≥50% pain relief, ≥20% improvement of health‐related quality of life, psychological distress, disability, acceptability and safety at end of therapy and 3‐month follow‐up. Effects were summarized by a random effects model using risk differences (RD) or standardized mean differences (SMD) with 95% confidence intervals (CI).Seven RCTs with 387 subjects were included into a comparison of GI/H versus controls. There was a clinically relevant benefit of GI/H compared to controls on ≥50% pain relief RD 0.18 (95% CI 0.02, 0.35) and psychological distress SMD −0.40 (95% CI −0.70, −0.11) at the end of therapy. Acceptability at the end of treatment for GI/H was not significantly different to the control. Two RCTs with 95 subjects were included in the comparison of hypnosis combined with cognitive behavioural therapy (CBT) versus CBT alone. Combined therapy was superior to CBT alone in reducing psychological distress at the end of therapy SMD −0.50 (95% CI −0.91, −0.09). There were no statistically significant differences between combined therapy and CBT alone in other primary outcomes at the end of treatment and follow‐up. No study reported on safety.
GI/H hold promise in a multicomponent management of fibromyalgia.
Significance
We provide a systematic review with meta‐analysis on guided imagery and hypnosis for fibromyalgia. Current analyses endorse the efficacy and tolerability of guided imagery/hypnosis and of the combination of hypnosis with cognitive–behavioural therapy in reducing key symptoms of fibromyalgia.
On‐treatment levels of hepatitis B surface antigen (HBsAg) may predict response to peginterferon (PEG‐IFN) therapy in chronic hepatitis B (CHB), but previously proposed prediction rules have shown ...limited external validity. We analyzed 803 HBeAg‐positive patients treated with PEG‐IFN in three global studies with available HBsAg measurements. A stopping‐rule based on absence of a decline from baseline was compared to a prediction‐rule that uses HBsAg levels of <1,500 IU/mL and >20,000 IU/mL to identify patients with high and low probabilities of response. Patients with an HBsAg level <1,500 IU/mL at week 12 achieved response (HBeAg loss with HBV DNA <2,000 IU/mL at 6 months posttreatment) in 45%. At week 12, patients without a decline in HBsAg achieved a response in 14%, compared to only 6% of patients with HBsAg >20,000 IU/mL, but performance varied across HBV genotype. In patients treated with PEG‐IFN monotherapy (n = 465), response rates were low in patients with genotypes A or D if there was no decline of HBsAg by week 12 (negative predictive value NPV: 97%‐100%), and in patients with genotypes B or C if HBsAg at week 12 was >20,000 IU/mL (NPV: 92%‐98%). At week 24, nearly all patients with HBsAg >20,000 IU/mL failed to achieve a response, irrespective of HBV genotype (NPV for response and HBsAg loss 99% and 100%). Conclusion: HBsAg is a strong predictor of response to PEG‐IFN in HBeAg‐positive CHB. HBV genotype‐specific stopping‐rules may be considered at week 12, but treatment discontinuation is indicated in all patients with HBsAg >20,000 IU/mL at week 24, irrespective of HBV genotype. (Hepatology 2013;53:872–880)
With more than 40% of the world's population at risk, 200-300 million infections each year, and an estimated 1.2 million deaths annually, malaria remains one of the most important public health ...problems of mankind today. With the propensity of malaria parasites to rapidly develop resistance to newly developed therapies, and the recent failures of artemisinin-based drugs in Southeast Asia, there is an urgent need for new antimalarial compounds with novel mechanisms of action to be developed against multidrug resistant malaria. We present here a novel image analysis algorithm for the quantitative detection and classification of Plasmodium lifecycle stages in culture as well as discriminating between viable and dead parasites in drug-treated samples. This new algorithm reliably estimates the number of red blood cells (isolated or clustered) per fluorescence image field, and accurately identifies parasitized erythrocytes on the basis of high intensity DAPI-stained parasite nuclei spots and Mitotracker-stained mitochondrial in viable parasites. We validated the performance of the algorithm by manual counting of the infected and non-infected red blood cells in multiple image fields, and the quantitative analyses of the different parasite stages (early rings, rings, trophozoites, schizonts) at various time-point post-merozoite invasion, in tightly synchronized cultures. Additionally, the developed algorithm provided parasitological effective concentration 50 (EC50) values for both chloroquine and artemisinin, that were similar to known growth inhibitory EC50 values for these compounds as determined using conventional SYBR Green I and lactate dehydrogenase-based assays.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
•Surprisingly, recent papers claim higher sonochemical production of H2 under pure CO2.•Modeling considerations of the sonolytic formation of H2 under different saturation gases are ...highlighted.•Dissolved gases affect the sonochemical production of H2 through physical and chemical pathways.•For CO2-saturated water, degassing bubbles are formed instead of transient cavitation.•CO2 effects on sonolytic production of H2 in recent papers are mostly due to wrong procedures.
Although most of researchers agree on the elementary reactions behind the sonolytic formation of molecular hydrogen (H2) from water, namely the radical attack of H2O and H2O2 and the free radicals recombination, several recent papers ignore the intervention of the dissolved gas molecules in the kinetic pathways of free radicals, and hence may wrongly assess the effect of dissolved gases on the sonochemical production of hydrogen. One may fairly ask to which extent is it acceptable to ignore the role of the dissolved gas and its eventual decomposition inside the acoustic cavitation bubble? The present opinion paper discusses numerically the ways in which the nature of dissolved gas, i.e., N2, O2, Ar and air, may influence the kinetics of sonochemical hydrogen formation. The model evaluates the extent of direct physical effects, i.e., dynamics of bubble oscillation and collapse events if any, against indirect chemical effects, i.e., the chemical reactions of free radicals formation and consequently hydrogen emergence, it demonstrates the improvement in the sonochemical hydrogen production under argon and sheds light on several misinterpretations reported in earlier works, due to wrong assumptions mainly related to initial conditions. The paper also highlights the role of dissolved gases in the nature of created cavitation and hence the eventual bubble population phenomena that may prevent the achievement of the sonochemical activity. This is particularly demonstrated experimentally using a 20 kHz Sinaptec transducer and a Photron SA 5 high speed camera, in the case of CO2-saturated water where degassing bubbles are formed instead of transient cavitation.
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