110 research outputs found
Modeled contrast in the response of the surface energy balance to heat waves for forest and grassland
Observations have shown that differences in surface energy fluxes over grasslands and forests are amplified during heat waves. The role of land-atmosphere feedbacks in this process is still uncertain. In this study, a single-column model (SCM) is used to investigate the difference between forest and grassland in their energy response to heat waves. Three simulations for the period 2005-11 were carried out: a control run using vegetation characteristics for Cabauw (the Netherlands), a run where the vegetation is changed to 100% forest, and a run with 100% short grass as vegetation. A surface evaporation tendency equation is used to analyze the impact of the land-atmosphere feedbacks on evapotranspiration and sensible heat release under normal summer and heat wave conditions with excessive shortwave radiation. Land-atmosphere feedbacks modify the contrast in surface energy fluxes between forest and grass, particularly during heat wave conditions. The surface resistance feedback has the largest positive impact, while boundary layer feedbacks generally tend to reduce the contrast. Overall, forests give higher air temperatures and drier atmospheres during heat waves. In offline land surface model simulations, the difference between forest and grassland during heat waves cannot be diagnosed adequately owing to the absence of boundary layer feedbacks
Data analysis model selection for estimating local population size of the Rissoâs dolphin (Grampus griseus) in the Azores
27th Annual Conference of the European Cetacean Society. SetĂșbal, Portugal, 8-10 April 2013.Different models estimating cetacean population size require making assumptions about the marking and recapturing of individuals, and on the structure of the population. Crucial in selecting the most appropriate model is a critical assessment of these assumptions. In this study we applied the robust parameterization of the open Jolly-Seber (JS) model (POPAN), using the software program MARK. This model was applied to data collected on the Rissoâs dolphin (Grampus griseus). Between 2004 â 2007, photo-identification was used as a Capture-Mark-Recapture technique to identify 670 unique individuals off Pico Island, Azores. For this model, it was assessed what assumptions are supported or violated. The aim of this study was improving our understanding of how to select the most appropriate population size model
Marine steppingâstones: Connectivity of Mytilus edulis populations between offshore energy installations
Recent papers have suggested that epifaunal organisms use artificial structures as steppingâstones to spread to areas that are too distant to reach in a single generation. With thousands of artificial structures present in the North Sea, we test the hypothesis that these structures are connected by water currents and act as an interconnected reef. Population genetic structure of the blue mussel, Mytilus edulis, was expected to follow a pattern predicted by a particle tracking model (PTM). Correlation between population genetic differentiation, based on microsatellite markers, and particle exchange was tested. Specimens of M. edulis were found at each location, although the PTM indicated that locations >85 km offshore were isolated from coastal subpopulations. The fixation coefficient FST correlated with the number of arrivals in the PTM. However, the number of effective migrants per generation as inferred from coalescent simulations did not show a strong correlation with the arriving particles. Isolation by distance analysis showed no increase in isolation with increasing distance and we did not find clear structure among the populations. The marine steppingâstone effect is obviously important for the distribution of M. edulis in the North Sea and it may influence ecologically comparable species in a similar way. In the absence of artificial shallow hard substrates, M. edulis would be unlikely to survive in offshore North Sea waters
Humpback whales interfering when mammal-eating killer whales attack other species: mobbing behavior and interspecific altruism?
Humpback whales (Megaptera novaeangliae) are known to interfere with attacking killer whales (Orcinus orca). To investigate why, we reviewed accounts of 115 interactions between them. Humpbacks initiated the majority of interactions (57% vs. 43%; n=72), although the killer whales were almost exclusively mammal-eating forms (MEKWs, 95%) vs. fish-eaters (5%; n=108). When MEKWs approached humpbacks (n=27), they attacked 85% of the time and targeted only calves. When humpbacks approached killer whales (n=41), 93% were MEKWs, and >87% of them were attacking or feeding on prey at the time. When humpbacks interacted with attacking MEKWs, 11% of the prey were humpbacks and 89% comprised 10 other species, including 3 cetaceans, 6 pinnipeds, and 1 teleost fish. Approaching humpbacks often harassed attacking MEKWs (>55% of 56 interactions), regardless of the prey species, which we argue was mobbing behavior. Humpback mobbing sometimes allowed MEKW prey, including nonhumpbacks, to escape. We suggest that humpbacks initially responded to vocalizations of attacking MEKWs without knowing the prey species targeted. Although reciprocity or kin selection might explain communal defense of conspecific calves, there was no apparent benefit to humpbacks continuing to interfere when other species were being attacked. Interspecific altruism, even if unintentional, could not be ruled out
The self-perceived palliative care barriers and educational needs of clinicians working in hospital primary care teams and referral patterns: lessons learned from a single-center survey and cohort study
Background: Within the generalist-plus-specialist palliative care model, palliative care is mainly provided by nurses and physicians of hospital primary care teams. Palliative care consultation teams (PCCTs) support these clinicians in adequately caring for patients with advanced illnesses. Our team started in 2012. The aim of this study was to assess the self-perceived barriers, educational needs and awareness of available palliative care support options among our hospital primary care teams. In addition, palliative care referral patterns were evaluated.Methods: Single-center mixed methods study. Outcomes of two surveys of primary care team clinicians (2012 and 2016) on barriers to palliative care, educational needs and awareness of palliative care support options were compared ( chi-square, Mann-Whitney U tests, qualitative analysis). Palliative care referral characteristics were evaluated [2012- 2017], including referral timing (survival since referral) (descriptive statistics, Kaplan-Meier methodology). Predictions of survival at referral were analyzed (weighted Kappa).Results: In 2012 and 2016, the most frequently reported barrier was the late initiation of the palliative care approach. Clinicians reported a need for education on physical symptom management and basic palliative care principles. Awareness of support options increased from 2012 to 2016, including improved familiarity with the PCCT (56% vs. 85%, P= 3 months after referral) (P=0.016). Median survival after referral was 0.9 (range, 0-83.3) months. Referring physicians overestimated survival in 44% of patients (kappa 0.36, 95% CI: 0.30-0.42).Conclusions: Primary care team clinicians persistently reported needing support with basic palliative care skills. PCCTs should continuously focus on educating primary care teams and promoting the use of guidelines. Because physicians tend to overestimate survival and usually referred patients late for specialist palliative care, consultation teams should support primary care teams to identify, treat and refer patients with palliative care needs in a timely manner.Biological, physical and clinical aspects of cancer treatment with ionising radiatio
Simulated land ice: latitudinal changes (0-2.6 Ma) and importance of CO2-glaciation divergence during times of decreasing obliquity (0-800 ka)
Following Milankovitch's theory the incoming insolation or summer energy at 65°N is typically analysed to predict the waxing or waning of land ice. We here use a model-based deconvolution of the LR04 benthic-d18O stack into land ice distribution (de Boer et al., 2014, Köhler et al., 2015) to verify if the latitudinal focal point of land ice dynamics has changed over the last 2 Myr or whether this choice of 65°N in orbital data is indeed well justified. We find that the 5°-latitudinal band which contributes most to land ice albedo radiative forcing (ÎR_[LI]) is 70-75°N between 2.0-1.5 Myr, which is then until 1.0 Myr gradually substituted by 65-70°N. During the last 1 Myr both 60-65°N and 65-70°N dominate ÎR_[LI] and contribute approximately the same amount, while the relative importance of 70-75°N is shrinking. Our analyses illustrates that the choice of 65°N seems for the last 1 Myr to be well justified, while for earlier parts of the last 2 Myr the dominant land ice changes seems to happen up to 10° further to the north.
Focusing on the last 800 kyr (the time for which precise data on atmospheric CO2 concentration exists) we furthermore find that the multi-millennial land ice growth and proxy-based reconstruction of global cooling (= the glaciation) appear synchronously to each other and to decreasing obliquity, but diverge from CO2. This suggests that the global cooling associated with Earth's way into an ice age as deduced in the reconstructions has to be mainly caused by the land ice albedo feedback, and is not dominated by the CO2 greenhouse forcing. One way of perceiving this CO2-glaciation divergence in reconstructions is that the reduced incoming insolation at high latitudes causes land ice growth and cooling, while there is a coexisting process that keeps CO2 at a relatively constant level. Solid Earth modeling experiments have indicated that falling sea level might lead to enhanced magma and CO2 production at mid-ocean ridges. Hasenclever et al. (2017) suggested that the combination of marine volcanism at mid-ocean ridges and at hot spot island volcanoes might react to decreasing sea level and be a potential cause for this CO2-glaciation divergence.
This CO2-glaciation divergence needs to be considered, when using paleo data to quantify paleoclimate sensitivity: periods with diverging CO2 and global temperature change should be filtered out when approximating the relationship between global temperature rise and CO2 concentrations (Köhler et al., 2018).
References:
de Boer et al. (2014). https://doi.org/10.1038/ncomms3999.
Köhler et al. (2015). https://doi.org/10.5194/cp-11-1801-2015.
Hasenclever et al. (2017). https://doi.org/10.1038/ncomms15867.
KoÌhler et al. (2018). https://doi.org/10.1029/2018GL077717
The transient response of ice volume to orbital forcing during the warm Late Pliocene
Examining the nature of ice sheet and sea level response to past episodes of enhanced greenhouse gas forcing may help constrain future sea level change. Here, for the first time, we present the transient nature of ice sheets and sea level during the late Pliocene. The transient ice sheet predictions are forced by multiple climate snapshots derived from a climate model set up with late Pliocene boundary conditions, forced with different orbital forcing scenarios appropriate to two Marine Isotope Stages (MISs), MIS KM5c, and K1. Our results indicate that during MIS KM5c both the Antarctic and Greenland ice sheets contributed to sea level rise relative to present and were relatively stable. Insolation forcing between the hemispheres was out of phase during MIS K1 and led to an asynchronous response of ice volume globally. Therefore, when variations of precession were high, inferring the behavior of ice sheets from benthic isotope or sea level records is complex
Feasibility and first results of the 'Trials-within-Cohorts' (TwiCs) design in patients undergoing radiotherapy for lung cancer
Background: 'Trials-within-Cohorts' (TwiCs), previously known as 'cohort multiple randomized controlled trials' is a pragmatic trial design, supporting an efficient and representative recruitment of patients for (future) trials. To our knowledge, the 'COhort for Lung cancer Outcome Reporting and trial inclusion' (COLOR) is the first TwiCs in lung cancer patients. In this study we aimed to assess the feasibility and first year results of COLOR. Material and Methods: All patients diagnosed with lung cancer referred to the Radiotherapy department were eligible to participate in the ongoing prospective COLOR study. At inclusion, written informed consent was requested for use of patient data, participation in patient-reported outcomes (PROs), and willingness to participate in (future) trials. Feasibility was studied by assessing participation and comparing baseline PROs to EORTC reference values. First-year results of PROs at baseline and 3âmonths after inclusion were evaluated separately for stereotactic body radiotherapy (SBRT) and conventional radiotherapy patients. Results: Of the 338 eligible patients between July 2020 and July 2021, 169 (50%) participated. Among these, 127 (75%) gave informed consent to PROs participation and 110 (65%) were willing to participate in (future) trials. The inclusion percentage dropped from 77% to 33% when the information procedure was switched from in-person to by phone (due to COVID-19 pandemic measures). Baseline PROs for physical and cognitive functioning were comparable in COLOR patients compared to the EORTC reference values. No significant changes in PROs were observed 3âmonths after inclusion, except for a slight increase in pain scores in the SBRT group ( n â=â97). Conclusions: The TwiCs-design appears feasible in lung cancer patients with fair participation rates (although negatively impacted by the COVID-19 pandemic). With a planned expansion to other centers, the COLOR-study is expected to enable multiple (randomized) evaluations of experimental interventions with important advantages for recruitment, generalizability, and long-term outcome data collection
An ultrasoft X-ray multi-microbeam irradiation system for studies of DNA damage responses by fixed- and live-cell fluorescence microscopy
Localized induction of DNA damage is a valuable tool for studying cellular DNA damage responses. In recent decades, methods have been developed to generate DNA damage using radiation of various types, including photons and charged particles. Here we describe a simple ultrasoft X-ray multi-microbeam system for high dose-rate, localized induction of DNA strand breaks in cells at spatially and geometrically adjustable sites. Our system can be combined with fixed- and live-cell microscopy to study responses of cells to DNA damage
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