1,172 research outputs found
Travelling waves and heteroclinic networks in models of spatially-extended cyclic competition
Dynamical systems containing heteroclinic cycles and networks can be invoked
as models of intransitive competition between three or more species. When
populations are assumed to be well-mixed, a system of ordinary differential
equations (ODEs) describes the interaction model. Spatially extending these
equations with diffusion terms creates a system of partial differential
equations which captures both the spatial distribution and mobility of species.
In one spatial dimension, travelling wave solutions can be observed, which
correspond to periodic orbits in ODEs that describe the system in a
steady-state travelling frame of reference. These new ODEs also contain a
heteroclinic structure. For three species in cyclic competition, the topology
of the heteroclinic cycle in the well-mixed model is preserved in the
steady-state travelling frame of reference. We demonstrate that with four
species, the heteroclinic cycle which exists in the well-mixed system becomes a
heteroclinic network in the travelling frame of reference, with additional
heteroclinic orbits connecting equilibria not connected in the original cycle.
We find new types of travelling waves which are created in symmetry-breaking
bifurcations and destroyed in an orbit flip bifurcation with a cycle between
only two species. These new cycles explain the existence of "defensive
alliances" observed in previous numerical experiments. We further describe the
structure of the heteroclitic network for any number of species, and we
conjecture how these results may generalise to systems of any arbitrary number
of species in cyclic competition
Adaptation of Thermal Power Plants: the (Ir)relevance of Climate (Change) Information
When does climate change information lead to adaptation? We analyze thermal power plant adaptation by means of investing in water-saving (cooling) technology to prevent a decrease in plant efficiency and load reduction. A comprehensive power plant investment model, forced with downscaled climate and hydrological projections, is then numerically solved to analyze the adaptation decisions of a selection of real power plants. We find that operators that base their decisions on current climatic conditions are likely to make identical choices and perform just as well as operators that are fully ’informed’ about climate change. Where electricity supply is mainly generated by thermal power plants, heat waves, droughts and low river flow may impact electricity supply for decades to come
Fish Allergy:Fishing for Novel Diagnostic and Therapeutic Options
Fish allergy is one of the most common food allergies. The currently recommended treatment commonly consists of avoiding all fish species. Recent literature suggests that these recommendations are overprotective for the majority of fish-allergic patients. This review summarizes recent findings and provides practical information regarding management of fish allergy in the individual patient. After precise history taking supported by additional specific IgE measurements and/or skin prick tests, fish-allergic patients can generally be categorized into the following clinical clusters: (A) poly-sensitized patients reacting to all fish species due to their sensitization to the panallergen β-parvalbumin, (B) mono-sensitized patients with selective reactions to individual fish species only, and (C) oligo-sensitized patients reacting to several specific fish. A number of allergens including parvalbumin, enolase, and aldolase can be involved. Depending on the specific cluster the patient belongs to, oral food challenges for one or more fish species can be performed with the aim to provide safe alternatives for consumption. This way, several alternative fish species can be identified for mono- and oligo-sensitized patients that can safely be consumed. Notably, even poly-sensitized patients generally tolerate fish species low in β-parvalbumin such as tuna and mackerel, particularly when processed. Taken together, allergological evaluation of patients with a documented fish allergy should be strongly considered, as it will allow the majority of patients to safely reintroduce one or more fish species
Positive effects of audit and feedback on antimicrobial use in hospitalized patients limited to audited patients
Objective: Audit and feedback is an antimicrobial stewardship (AMS) strategy, with the potential to also optimize antimicrobial use in non-audited patients. This study aimed to determine whether audit and feedback reduce antimicrobial use in both audited and non-audited patients.Design: Before-after trial with a 1-year intervention period and 2.5-year historical cohort.Setting: 750-bed community hospital in the Netherlands.Patients: All patients admitted to the urology wards during the 3.5-year study period were observed. Patients were classified as using antimicrobials if any antimicrobial was used for therapeutic reasons. Patients using antimicrobials prophylactically were excluded from measurements.Intervention: The AMS team provided audit and feedback on antimicrobial use for patients using antimicrobials for 2 days. Retrospectively, antimicrobial use and length of stay (LOS) were compared with the historical cohort.Results: Audits modified antimicrobial treatment in 52.8% of the cases. De-escalating, stopping, and switching from intravenous to oral treatment accounted for 72% of these modifications. Compared to patients from the cohort, who also used antimicrobials for 2 days, antimicrobial use decreased from 14.21 DDD/patient (95% CI, 13.08–15.34) to 11.45 DDD/patient (95% CI, 8.26–14.64; P = .047) for audited patients. Furthermore, mean LOS decreased from 7.42 days (95% CI, 6.79–8.06) to 6.13 days (95% CI, 5.38–6.89; P = .031). However, looking at all patients admitted to the urology wards, the percentage of patients using antimicrobials and total antimicrobial use remained unchanged.Conclusions: Audit and feedback reduce antimicrobial use and LOS, but only for audited patients. Positive effects are not automatically transferred to patients for whom no audits have been performed
MUC5B levels in submandibular gland saliva of patients treated with radiotherapy for head-and-neck cancer: A pilot study
<p>Abstract</p> <p>Background</p> <p>The salivary mucin MUC5B, present in (sero)mucous secretions including submandibular gland (SMG) saliva, plays an important role in the lubrication of the oral mucosa and is thought to be related to the feeling of dry mouth. We investigated if MUC5B levels in SMG saliva could distinguish between the presence or absence of severe dry mouth complaints 12 months after radiotherapy (RT) for head-and-neck cancer (HNC).</p> <p>Findings</p> <p>Twenty-nine HNC patients with a residual stimulated SMG secretion rate of ≥0.2 ml/10 min at 12 months after RT were analyzed. MUC5B (in U; normalized to 1) and total protein levels (mg/ml) were measured in SMG saliva at baseline and 12 months after RT using ELISA and BCA protein assay, respectively. Overall, median MUC5B levels decreased after RT from 0.12 to 0.03 U (<it>p</it> = 0.47). Patients were dichotomized into none/mild xerostomia (n = 12) and severe xerostomia (n = 17) based on a questionnaire completed at 12 months. SMG and whole saliva flow rates decreased after RT but were comparable in both groups. The median MUC5B level was higher in patients with no or mild xerostomia compared to patients with severe xerostomia (0.14 vs 0.01 U, <it>p</it> = 0.22). Half of the patients with severe xerostomia had no detectable MUC5B at 12 months after RT. No differences in total protein levels were observed.</p> <p>Conclusions</p> <p>Qualitative saliva parameters like MUC5B need further investigation in RT-induced xerostomia. This pilot study showed a trend towards lower MUC5B levels in the SMG saliva of patients with severe xerostomia 12 months after RT for HNC.</p
Two-qubit logic between distant spins in silicon
Direct interactions between quantum particles naturally fall off with
distance. For future-proof qubit architectures, however, it is important to
avail of interaction mechanisms on different length scales. In this work, we
utilize a superconducting resonator to facilitate a coherent interaction
between two semiconductor spin qubits 250 m apart. This separation is
several orders of magnitude larger than for the commonly employed direct
interaction mechanisms in this platform. We operate the system in a regime
where the resonator mediates a spin-spin coupling through virtual photons. We
report anti-phase oscillations of the populations of the two spins with
controllable frequency. The observations are consistent with iSWAP oscillations
and ten nanosecond entangling operations. These results hold promise for
scalable networks of spin qubit modules on a chip.Comment: 17 pages, 9 figure
Excessive toxicity of cabozantinib in a phase II study in patients with recurrent and/or metastatic salivary gland cancer
AIM: Because the tyrosine kinases c-MET and vascular endothelial growth factor receptors (VEGFR) are often overexpressed in salivary gland cancer (SGC), this study evaluated the efficacy and safety of cabozantinib in patients with recurrent/metastatic (R/M) SGC. PATIENTS AND METHODS: A single-centre phase II study was conducted. Patients with immunohistochemical c-MET-positive R/M SGC were included in three cohorts: adenoid cystic carcinoma (ACC); salivary duct carcinoma (SDC) and other miscellaneous SGCs. No prior systemic treatments were required. Patients started cabozantinib 60 mg once daily. The primary outcome was the objective response rate (ORR). Secondary outcomes included survival, safety and quality of life. Per Simon-two-stage design, depending on efficacy, a maximum of 43 patients would be included. RESULTS: In total, 25 patients were included until premature closure owing to severe toxicity. Six patients (24%) had grade 3-5 wound complications, occurring at a median of 7.1 months on cabozantinib treatment (range 2.1-12.6). Remarkably, four of these six patients developed this complication in the area prior exposed to high-dose radiotherapy. Other grade ≥3 adverse events in >1 patient were hypertension (20%), diarrhoea (8%) and dehydration (8%). Twenty-one patients were evaluable for response; 1/15 ACC (ORR: 7%); 1/4 SDC and 0/2 patients with other miscellaneous SGC responded. Median progression-free survival was 9.4 months (95% confidence interval [CI] 7.4-11.4 months), 7.2 months (95%CI 0.0-15.1) and 6.9 months (95%CI 0.0-15.1), respectively. CONCLUSION: This study showed too many severe cabozantinib-associated wound complications in patients with SGC, especially in prior irradiated areas. Therefore, the study closed prematurely. The efficacy in the limited number of evaluable patients was low to moderate. TRIAL REGISTRATION: This trial was registered on ClinicalTrials.gov: NCT03729297
Reaching thermal noise at ultra-low radio frequencies: the Toothbrush radio relic downstream of the shock front
Ultra-low frequency observations (<100 MHz) are particularly challenging
because they are usually performed in a low signal-to-noise ratio regime due to
the high sky temperature and because of ionospheric disturbances whose effects
are inversely proportional to the observing frequency. Nonetheless, these
observations are crucial to study the emission from low-energy populations of
cosmic rays. We aim to obtain the first thermal-noise limited (~ 1.5 mJy/beam)
deep continuum radio map using the LOFAR Low Band Antenna (LBA) system. Our
demonstration observation targeted the galaxy cluster RX J0603.3+4214 (the
"Toothbrush" cluster). We used the resulting ultra-low frequency (58 MHz) image
to study cosmic-ray acceleration and evolution in the post shock region, as
well as their relation with the presence of a radio halo. We describe the data
reduction we have used to calibrate LOFAR LBA observations. The resulting image
is combined with observations at higher frequencies (LOFAR 150 MHz and VLA 1500
MHz) to extract spectral information. We obtained the first thermal-noise
limited image from an observation carried out with the LOFAR LBA system using
all Dutch stations at a central frequency of 58 MHz. With 8 hours of data, we
reached an rms noise of 1.3 mJy/beam at a resolution of 18" x 11". The
procedure we have developed is an important step forward towards routine
high-fidelity imaging with the LOFAR LBA. The analysis of the radio spectra
shows that the radio relic extends to distances of 800 kpc downstream from the
shock front, larger than what allowed by electron cooling time. Furthermore,
the shock wave started accelerating electrons already at a projected distance
of <300 kpc from the crossing point of the two clusters. These results can be
explained if electrons are reaccelerated downstream by background turbulence
possibly combined with projection effects.Comment: 15 pages, 19 figures, accepted A&
Climate adaptation of interconnected infrastructures: a framework for supporting governance
Infrastructures are critical for human society, but vulnerable to climate change. The current body of research on infrastructure adaptation does not adequately account for the interconnectedness of infrastructures, both internally and with one another. We take a step toward addressing this gap through the introduction of a framework for infrastructure adaptation that conceptualizes infrastructures as complex socio-technical “systems of systems” embedded in a changing natural environment. We demonstrate the use of this framework by structuring potential climate change impacts and identifying adaptation options for a preliminary set of cases—road, electricity and drinking water infrastructures. By helping to clarify the relationships between impacts at different levels, we find that the framework facilitates the identification of key nodes in the web of possible impacts and helps in the identification of particularly nocuous weather conditions. We also explore how the framework may be applied more comprehensively to facilitate adaptation governance. We suggest that it may help to ensure that the mental models of stakeholders and the quantitative models of researchers incorporate the essential aspects of interacting climate and infrastructure systems. Further research is necessary to test the framework in these contexts and to determine when and where its application may be most beneficial.Infrastructure Networks Climate Adaptation and Hotspots. Knowledge for Climate Progra
Increased genetic contribution to wellbeing during the COVID-19 pandemic
Physical and mental health are determined by an interplay between nature, for example genetics, and nurture, which encompasses experiences and exposures that can be short or long-lasting. The COVID-19 pandemic represents a unique situation in which whole communities were suddenly and simultaneously exposed to both the virus and the societal changes required to combat the virus. We studied 27,537 population-based biobank participants for whom we have genetic data and extensive longitudinal data collected via 19 questionnaires over 10 months, starting in March 2020. This allowed us to explore the interaction between genetics and the impact of the COVID-19 pandemic on individuals' wellbeing over time. We observe that genetics affected many aspects of wellbeing, but also that its impact on several phenotypes changed over time. Over the course of the pandemic, we observed that the genetic predisposition to life satisfaction had an increasing influence on perceived quality of life. We also estimated heritability and the proportion of variance explained by shared environment using variance components methods based on pedigree information and household composition. The results suggest that people's genetic constitution manifested more prominently over time, potentially due to social isolation driven by strict COVID-19 containment measures. Overall, our findings demonstrate that the relative contribution of genetic variation to complex phenotypes is dynamic rather than static
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