The dynamics of granular mixtures, involved in several geophysical phenomena like rock avalanches and debris flows, is far from being completely understood. Several features of their motion, such as ...non-local and boundary effects, still represent open problems. An extensive experimental study on free-surface channelized granular flows is here presented, where the effects of the fixed boundaries are systematically investigated. The entire experimental data set is obtained by using a homogenous acetal-polymeric granular material and three different basal surfaces, allowing different kinematic boundary conditions. Velocity profiles at both the sidewall and the free surface are obtained by using high-speed cameras and the open-source particle image velocimetry code, PIVlab. Significantly, different sidewall velocity profiles are observed by varying the basal roughness and the flow depth. Owing to sidewall friction and non-local effects, such profiles exhibit a clear rheological stratification for high enough flow depths and they can be well described by recurring to composite functions, variously formed of linear, Bagnold and exponential scalings. Moreover, it has been discovered that transitions from one velocity profile to another are also possible on the same basal surface by merely varying the flow depth. This shape transition is due partly to the sidewall resistances, the basal boundary condition and, in particular, the occurrence/inhibition of basal grain rolling. In most of the experiments, the normal-to-bed velocity profiles and the velocity measurements at the free surface strongly suggest the occurrence of a secondary circulating flow, made possible by a chiefly collisional regime beneath the free surface.
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Many fundamental questions remain in the elucidation of energy migration mechanisms across the interface between semiconductor nanomaterials and molecular chromophores. The present transient ...absorption study focuses on PbS quantum dots (QDs) of variable size and band-edge exciton energy (ranging from 1.15 to 1.54 eV) post-synthetically modified with a carboxylic acid-functionalized TIPS-pentacene derivative (TPn) serving as the molecular triplet acceptor. In all instances, selective excitation of the PbS NCs at 743 nm leads to QD size-dependent formation of an intermediate with time constants ranging from 2-13 ps, uncorrelated to the PbS QD valence band potential. However, the rate constant for the delayed formation of the TPn triplet excited state markedly increases with increasing PbS conduction band energy, featuring a parabolic Marcus free energy dependence in the normal region. These observations provide evidence of an indirect triplet sensitization process being inconsistent with a concerted Dexter-like energy transfer process. The collective data are consistent with the generation of an intermediate resulting from hole trapping of the initial PbS excited state by midgap states, followed by formation of the TPn triplet excited state whose rate constant and yield increases with decreasing quantum dot size.
Many fundamental questions remain in the elucidation of energy migration mechanisms across the interface between semiconductor nanomaterials and molecular chromophores.
Full text
Available for:
IJS, KILJ, NUK, UL, UM, UPUK
Transcription factors required for formation of embryonic tissues often maintain their expression in adult stem cell populations, but whether their function remains equivalent is not clear. Here we ...demonstrate critical and distinct roles for Sall4 in development of embryonic germ cells and differentiation of postnatal spermatogonial progenitor cells (SPCs). In differentiating SPCs, Sall4 levels transiently increase and Sall4 physically interacts with Plzf, a transcription factor exclusively required for adult stem cell maintenance. Mechanistically, Sall4 sequesters Plzf to noncognate chromatin domains to induce expression of Kit, a target of Plzf-mediated repression required for differentiation. Plzf in turn antagonizes Sall4 function by displacing Sall4 from cognate chromatin to induce Sall1 expression. Taken together, these data suggest that transcription factors required for embryonic tissue development postnatally take on distinct roles through interaction with opposing factors, which hence define properties of the adult stem cell compartment.
Display omitted
► Sall4 is required for embryonic germ cell maintenance ► Differentiation of spermatogonial progenitor cells (SPCs) is Sall4 dependent ► Sall4 physically interacts with Plzf in SPCs ► Sall4 and Plzf antagonistically regulate Kit and Sall1 to define SPC function
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
A thin layer of fresh water from summer monsoon rain and river runoff in the Bay of Bengal (BoB) has profound influence on air‐sea interaction across the south Asian region, but the mechanisms that ...sustain the low‐salinity layer are as yet unknown. Using the first long time series of high‐frequency observations from a mooring in the north BoB and satellite salinity data, we show that fresh water from major rivers is transported by large‐scale flow and eddies, and shallow salinity stratification persists from summer through the following winter. The moored observations show frequent 0.2–1.2 psu salinity jumps with time scales of 10 min to days, due to O(1–10) km submesoscale salinity fronts moving past the mooring. In winter, satellite sea surface temperature shows 10 km wide filaments of cool water, in line with moored data. Rapid salinity and temperature changes at the mooring are highly coherent, suggesting slumping of salinity‐dominated fronts. Based on these observations, we propose that submesoscale fronts may be one of the important drivers for the persistent fresh layer in the north BoB.
Key Points
Persistence of shallow stratification and river water from moored data in the north Bay of Bengal
First evidence of submesoscale (order 1–10 km) salinity fronts in the Bay of Bengal
Slumping of submesoscale fronts may sustain shallow stratification
Full text
Available for:
FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Summary
Background
Psoriasis is an emerging paradoxical side effect in patients with inflammatory bowel disease (IBD) when treated with anti‐TNF alpha. Patients with severe skin lesions unresponsive ...to topical therapy need to withdraw from treatment.
Aim
To estimate the incidence of paradoxical psoriasis in a large cohort of IBD patients treated with anti‐TNF alpha and to analyse its clinical correlates.
Methods
A retrospective cohort study on all IBD patients who started anti‐TNF alpha at our IBD Centre from January 2008 to December 2013 was performed. Proportional hazards regression models were used to estimate the association between each predictor and time to the development of psoriasis. Time‐dependent predictors were updated at each available time point.
Results
Four hundred and two patients were included. Participants contributed a total of 839 person‐years of follow‐up, during which 42 incident cases of psoriasis were recorded, with an incidence rate of five per 100 person‐years. Cox‐regression survival analysis revealed smoking as independent predictor of psoriasis (HR: 2.37, 95% CI: 1.36–4.48; P = 0.008). Conversely, concomitant immunosuppressive therapy was inversely related to psoriasis (HR: 0.33, 95% CI: 0.12–0.92; P = 0.03).
Conclusions
Paradoxical psoriasis is a relevant side effect of anti‐TNF alpha therapy, with an incidence rate of five per 100 person‐years. Smoking is confirmed as the main risk factor for developing lesions. The combination therapy with anti‐TNF alpha plus immunosuppressants is associated with a reduced risk of paradoxical psoriasis.
Full text
Available for:
BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK
•348 P. falciparum samples from 327 patients collected from 2015–2019 in Hôpital Principal de Dakar, Senegal.•16 patients (4.9%) still parasitaemic on Day 3 after t artemisinin-based combination ...therapy (ACT).•All sequences had wild-type pfk13 allele.•Identification of P76S mutation in pfcoronin (mean prevalence16.2%).•No significant association between in vivo reduced efficacy to ACT and P76S mutation.
Due to resistance to chloroquine and sulfadoxine/pyrimethamine, treatment for uncomplicated Plasmodium falciparum malaria switched to artemisinin-based combination therapy (ACT) in 2006 in Senegal. Several mutations in the gene encoding the kelch13 helix (pfk13-propeller) have been identified as associated with in vitro and in vivo artemisinin resistance in Southeast Asia. Additionally, three mutations in the pfcoronin gene (G50E, R100K and E107V) have been identified in two culture-adapted Senegalese field isolates that became resistant in vitro to artemisinin after 4 years of intermittent selection with dihydroartemisinin. The aims of this study were to assess the prevalence of pfcoronin and pfk13 mutations in Senegalese field isolates from Dakar and to investigate their association with artemisinin derivative clinical failures. A total of 348 samples of P. falciparum from 327 patients, collected from 2015–2019 in Dakar, were successfully analysed. All sequences had wild-type pfk13 allele. The three mutations (G50E, R100K and E107V), previously identified in parasites with reduced susceptibility to artemisinin, were not found in this study, but a new mutation (P76S) was detected (mean prevalence 16.2%). The P76S mutation was identified in 5 (31.3%) of 16 isolates collected from patients still parasitaemic on Day 3 after ACT treatment and in 31 samples (15.3%) among 203 patients considered successfully cured. There was no significant association between in vivo reduced efficacy to artemisinin derivatives and the P76S mutation (P = 0.151, Fisher's exact test). These data suggest that polymorphisms in pfk13 and pfcoronin are not the best predictive markers for artemisinin resistance in Senegal.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Although several arboviruses—such as dengue (DENV), Zika (ZIKV) and chikungunya (CHIKV) viruses—are not endemic in Europe, they have the potential to emerge following importation of the virus, taking ...advantage of the favourable climate and ecosystem. DENV, ZIKV and CHIKV are transmitted by Aedes species mosquitoes and are amongst the most common travel-associated arboviruses. Furthermore, they are linked to sporadic, local outbreaks, especially in the southern parts of Europe. In this review we present in brief the DENV, ZIKV and CHIKV cases imported to Greece during the last 6 years (2013–2018), and we describe the recent laboratory data obtained from the Hellenic Pasteur Institute and the National Reference Centre for Arboviruses. We report 21 imported cases of DENV, ZIKV and CHIKV infections in travellers arriving in Greece. The probable origins were south-eastern Asian (71%) and north-central American (29%) countries. Furthermore, we stress the importance of early and accurate diagnosis in spite of a plethora of diagnostic challenges that clinicians and virologists have to face. Altogether, with the authorities' awareness and the preventive measures to be applied, local transmission events can be successfully avoided, especially in summer when the temperature is favourable for mosquito-borne infections.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Basalt-epoxy laminates are establishing gradually in engineering sectors due to increasing attention toward environmental matters. Some properties should be improved to extend their applications and ...the cold spray (CS) metallization provides a potential solution. Unfortunately, the fragile nature of thermosetting polymers makes it difficult the CS coating formation and grow-up. Therefore, this research work aims to study an innovative solution able to enhance the adhesion mechanisms between the cold sprayed metal particles and the thermosetting polymer-based substrates. For this purpose, an original manufacturing method that provides the surface PLA treatment for thermosetting samples was developed. AlSi10Mg particles were cold sprayed on the treated surface, and the low-velocity impact behaviour of the metallised hybrid structures was analysed in details. The outcomes prove the effectiveness of the method proposed on the deposition process and the beneficial effects of metallization on impact damage mechanisms.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
A large body of work during the past several decades has been focused on therapeutic strategies to control L-DOPA-induced dyskinesias (LIDs), common motor complications of long-term L-DOPA therapy in ...Parkinson's disease (PD). Yet, LIDs remain a clinical challenge for the management of patients with advanced disease. Glutamatergic dysregulation of striatal projection neurons (SPNs) appears to be a key contributor to altered motor responses to L-DOPA. Targeting striatal hyperactivity at the glutamatergic neurotransmission level led to significant preclinical and clinical trials of a variety of antiglutamatergic agents. In fact, the only FDA-approved treatment for LIDs is amantadine, a drug with NMDAR antagonistic actions. Still, novel agents with improved pharmacological profiles are needed for LID therapy. Recently other therapeutic targets to reduce dysregulated SPN activity at the signal transduction level have emerged. In particular, mechanisms regulating the levels of cyclic nucleotides play a major role in the transduction of dopamine signals in SPNs. The phosphodiesterases (PDEs), a large family of enzymes that degrade cyclic nucleotides in a specific manner, are of special interest. We will review the research for antiglutamatergic and PDE inhibition strategies in view of the future development of novel LID therapies.
Full text
Available for:
IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
You have reached the maximum number of search results that are displayed.
For better performance, the search offers a maximum of 1,000 results per query (or 50 pages if the option 10/page is selected).
Consider using result filters or changing the sort order to explore your results further.
PDF
