495 research outputs found
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Climate and Species Richness Predict the Phylogenetic Structure of African Mammal Communities
We have little knowledge of how climatic variation (and by proxy, habitat variation) influences the phylogenetic structure of tropical communities. Here, we quantified the phylogenetic structure of mammal communities in Africa to investigate how community structure varies with respect to climate and species richness variation across the continent. In addition, we investigated how phylogenetic patterns vary across carnivores, primates, and ungulates. We predicted that climate would differentially affect the structure of communities from different clades due to between-clade biological variation. We examined 203 communities using two metrics, the net relatedness (NRI) and nearest taxon (NTI) indices. We used simultaneous autoregressive models to predict community phylogenetic structure from climate variables and species richness. We found that most individual communities exhibited a phylogenetic structure consistent with a null model, but both climate and species richness significantly predicted variation in community phylogenetic metrics. Using NTI, species rich communities were composed of more distantly related taxa for all mammal communities, as well as for communities of carnivorans or ungulates. Temperature seasonality predicted the phylogenetic structure of mammal, carnivoran, and ungulate communities, and annual rainfall predicted primate community structure. Additional climate variables related to temperature and rainfall also predicted the phylogenetic structure of ungulate communities. We suggest that both past interspecific competition and habitat filtering have shaped variation in tropical mammal communities. The significant effect of climatic factors on community structure has important implications for the diversity of mammal communities given current models of future climate change
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Repetitive high energy pulsed power technology development for industrial applications
The technology base for Repetitive High Energy Pulsed Power (RHEPP) was originally developed to support defense program applications. As RHEPP technology matures, its potential for use in commercial applications can be explored based on inherent strengths of high average power, high dose rate, cost efficient scaling with power, and potential for long life performance. The 300 kW, 2 MeV RHEPP II accelerator is now in operation as a designated DOE User Facility, exploring applications where high dose-rate (> 10{sup 8} Gy/s) may be advantageous, or very high average power is needed to meet throughput requirements. Material surface and bulk property modification, food safety, and large-scale timber disinfestation are applications presently under development. Work is also in progress to generate the reliability database required for the design of 2nd generation systems
A dose-finding study of carboplatin–epirubicin–docetaxel in advanced epithelial ovarian cancer
The docetaxel–carboplatin combination is active and well tolerated in patients with epithelial ovarian cancer. We added epirubicin to this combination to investigate additional benefits of anthracyclines in epithelial ovarian cancer. Twenty-one patients, FIGO Ic-IV, performance status 0–1, were treated in four dose cohorts. Docetaxel was fixed at 75 mg m−2, carboplatin doses were AUC 4–5 and epirubicin doses were 50–60 mg m−2. Drugs were given on day 1, every 3 weeks, except in cohort 3, where epirubicin was given on day 8. Dexamethasone was given prophylactically. One dose-limiting toxicity occurred in cohorts 1, 2 and 4, two occurred in cohort 3. Complicated neutropenia occurred in two patients in cohorts 1 and 2 and one patient in cohorts 3 and 4. Two patients experienced grade III diarrhoea or stomatitis in cohort 1 and two in cohort 3. There were no treatment-related deaths. Grade II sensory neuropathy occurred in one patient. No cardiac toxicity or significant oedema was observed. The overall response rate was 36%, and 62% were CA125 responders. The predefined maximum tolerated dose was exceeded in cohort 3. The cohort 4 dose level (epirubicin 50 mg m−2, carboplatin AUC 4, docetaxel 75 mg m−2), warrants further study
Pharmacologic and Clinical Considerations of Nalmefene, a Long Duration Opioid Antagonist, in Opioid Overdose
Opioid use disorder is a well-established and growing problem in the United States. It is responsible for both psychosocial and physical damage to the affected individuals with a significant mortality rate. Given both the medical and non-medical consequences of this epidemic, it is important to understand the current treatments and approaches to opioid use disorder and acute opioid overdose. Naloxone is a competitive mu-opioid receptor antagonist that is used for the reversal of opioid intoxication. When given intravenously, naloxone has an onset of action of approximately 2 min with a duration of action of 60–90 min. Related to its empirical dosing and short duration of action, frequent monitoring of the patient is required so that the effects of opioid toxicity, namely respiratory depression, do not return to wreak havoc. Nalmefene is a pure opioid antagonist structurally similar to naltrexone that can serve as an alternative antidote for reversing respiratory depression associated with acute opioid overdose. Nalmefene is also known as 6-methylene naltrexone. Its main features of interest are its prolonged duration of action that surpasses most opioids and its ability to serve as an antidote for acute opioid overdose. This can be pivotal in reducing healthcare costs, increasing patient satisfaction, and redistributing the time that healthcare staff spend monitoring opioid overdose patients given naloxone
Adjuvant drugs for peripheral nerve blocks: The role of nmda antagonists, neostigmine, epinephrine, and sodium bicarbonate
The potential for misuse, overdose, and chronic use has led researchers to look for other methods to decrease opioid consumption in patients with acute and chronic pain states. The use of peripheral nerve blocks for surgery has gained increasing popularity as it minimizes peripheral pain signals from the nociceptors of local tissue sustaining trauma and inflammation from surgery. The individualization of peripheral nerve blocks using adjuvant drugs has the potential to improve patient outcomes and reduce chronic pain. The major limitations of peripheral nerve blocks are their limited duration of action and dose-dependent adverse effects. Adjuvant drugs for peripheral nerve blocks show increasing potential as a solution for postoperative and chronic pain with their synergistic effects to increase the duration of action and decrease the required dosage of local anesthetic. N-methyl-d-aspartate (NMDA) receptor antagonists are a viable option for patients with opioid resistance and neuropathic pain due to their affinity to the neurotransmitter glutamate, which is released when patients experience a noxious stimulus. Neostigmine is a cholinesterase inhibitor that exerts its effect by competitively binding at the active site of acetylcholinesterase, which prevents the hydrolysis of acetylcholine and subsequently retaining acetylcholine at the nerve terminal. Epinephrine, also known as adrenaline, can potentially be used as an adjuvant to accelerate and prolong analgesic effects in digital nerve blocks. The theorized role of sodium bicarbonate in local anesthetic preparations is to increase the pH of the anesthetic. The resulting alkaline solution enables the anesthetic to more readily exist in its un-ionized form, which more efficiently crosses lipid membranes of peripheral nerves. However, more research is needed to show the efficacy of these adjuvants for nerve block prolongation as studies have been either mixed or have small sample sizes
Zwicky Transient Facility constraints on the optical emission from the nearby repeating FRB 180916.J0158+65
The discovery rate of fast radio bursts (FRBs) is increasing dramatically
thanks to new radio facilities. Meanwhile, wide-field instruments such as the
47 deg Zwicky Transient Facility (ZTF) survey the optical sky to study
transient and variable sources. We present serendipitous ZTF observations of
the CHIME repeating source FRB 180916.J0158+65, that was localized to a spiral
galaxy 149 Mpc away and is the first FRB suggesting periodic modulation in its
activity. While 147 ZTF exposures corresponded to expected high-activity
periods of this FRB, no single ZTF exposure was at the same time as a CHIME
detection. No optical source was found at the FRB location in 683
ZTF exposures, totalling 5.69 hours of integration time. We combined ZTF upper
limits and expected repetitions from FRB 180916.J0158+65 in a statistical
framework using a Weibull distribution, agnostic of periodic modulation priors.
The analysis yielded a constraint on the ratio between the optical and radio
fluences of , corresponding to an optical energy erg for a fiducial 10 Jy ms FRB (90%
confidence). A deeper (but less statistically robust) constraint of can be placed assuming a rate of Jy ms)= hr and
FRB occurring during exposures taken in high-activity windows. The
constraint can be improved with shorter per-image exposures and longer
integration time, or observing FRBs at higher Galactic latitudes. This work
demonstrated how current surveys can statistically constrain multi-wavelength
counterparts to FRBs even without deliberately scheduled simultaneous radio
observation.Comment: Accepted for publication in ApJL, 9 pages, 4 figures, 1 tabl
SCOTROC 2A: Carboplatin followed by docetaxel or docetaxel–gemcitabine as first-line chemotherapy for ovarian cancer
The feasibility of sequential carboplatin followed by docetaxel-based therapy for untreated ovarian cancer was determined. Patients received four q3w cycles of carboplatin AUC 7, then four q3w cycles of either docetaxel 100 mg m−2 (day 1) (arm A); docetaxel 75 mg m−2 (day 8) and gemcitabine 1250 mg m−2 (days 1,8) (arm B) or docetaxel 25 mg m−2 and gemcitabine 800 mg m−2 (both given weekly (days 1,8,15)) (arm C). A total of 44 patients were randomised to each treatment arm. None of the arms demonstrated an eight cycle completion rate (70.5/72.7/45.5% in arms A/B/C, respectively), which was statistically greater than 60% (P=0.102, P=0.056, P=0.982) which was our formal feasibility criteria, although only the completion rate in arm C was clearly worse than this level. The overall response rate (ORR) after carboplatin was 65.7% in 70 evaluable patients. In evaluable patients, ORRs after docetaxel-based cycles were: arm A 84.0% (21 out of 25); arm B 77.3% (17 out of 22); arm C 69.6% (16 out of 23). At follow-up (median 30 months), median progression-free survival times were: arm A 15.5 months (95% CI: 10.5–20.6); arm B 18.1 months (95% CI: 15.9–20.3); arm C, 13.7 months (95% CI: 12.8–14.6). Neutropenia was the predominant grade 3–4 haematological toxicity: 77.8/85.7/54.4% in arms A/B/C, respectively. Dyspnoea was markedly increased in both gemcitabine-containing arms (P=0.001) but was worse in arm C. Although just failing to rule out eight cycle completion rates less than 60%, within the statistical limitations of these small cohorts, the overall results for arms A and B are encouraging. Larger phase III studies are required to test these combinations
A new class of large-amplitude radial-mode hot subdwarf pulsators
Using high-cadence observations from the Zwicky Transient Facility at low Galactic latitudes, we have discovered a new class of pulsating, hot compact stars. We have found four candidates, exhibiting blue colors (g − r ≤ −0.1 mag), pulsation amplitudes of >5%, and pulsation periods of 200–475 s. Fourier transforms of the light curves show only one dominant frequency. Phase-resolved spectroscopy for three objects reveals significant radial velocity, T eff, and log(g) variations over the pulsation cycle, which are consistent with large-amplitude radial oscillations. The mean T eff and log(g) for these stars are consistent with hot subdwarf B (sdB) effective temperatures and surface gravities. We calculate evolutionary tracks using MESA and adiabatic pulsations using GYRE for low-mass, helium-core pre-white dwarfs (pre-WDs) and low-mass helium-burning stars. Comparison of low-order radial oscillation mode periods with the observed pulsation periods show better agreement with the pre-WD models. Therefore, we suggest that these new pulsators and blue large-amplitude pulsators (BLAPs) could be members of the same class of pulsators, composed of young ≈0.25–0.35 M ⊙ helium-core pre-WDs.Published versio
Docetaxel-carboplatin as first line chemotherapy for epithelial ovarian cancer
A prospective, non-randomized, multicentre, open, dose-finding study of a carboplatin-docetaxel (C-D) combination as first-line chemotherapy in FIGO stage Ic–IV epithelial ovarian cancer. C-D was given 3-weekly for 6 planned cycles, with a 3-day prophylactic dexamethasone regimen (8 mg b.i.d.). 139 eligible patients (Pts) (median age 56 years, range 28–85) were given a total of 750 cycles of chemotherapy in 5 cohorts: Co1, 32 pts, 169 cycles (C at AUC 5 + D 60 mg/m2); Co2, 22 pts, 122 cycles (5 + 75), Co3, 29 pts, 156 cycles (6 + 75), Co4, 27 pts, 146 cycles (7 + 75), Co5, 30 pts, 157 cycles (6 + 85). 110 patients (79%) completed 6 cycles; 17 (12%) stopped due to toxicity. 104 patients (75%) had CTC grade IV neutropenia, and 5 patients (4%) had this associated with fever. There were 2 probable treatment-related deaths. Only 8 patients (6%) experienced grade II–III neurotoxicity (all sensory; no motor > grade I). The maximum tolerated dose was reached in cohorts 4 and 5, and the dose limiting toxicities were myelosuppression and diarrhoea. The overall response rate for the study was 66% (49/74); CA125 response was 75% (70/93). Median progression-free survival was 16.6 months (95% CI 13.3–19.1). Recommended doses are carboplatin AUC 5 (via51 Cr EDTA) or AUC 6 (if calculated) plus docetaxel 75 mg/m2. A randomized trial comparing this regimen with carboplatin-paclitaxel has just completed recruitment. © 2001 Cancer Research Campaign http://www.bjcancer.co
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