Energy and environmental stability are positively correlated with species richness along broad‐scale spatial gradients in terrestrial ecosystems, so their relative importance in generating and ...preserving diversity cannot be readily disentangled. This study seeks to exploit the negative correlation between energy and stability along the oceanic depth gradient to better understand their relative contribution in shaping broadscale biodiversity patterns. We develop a conceptual framework by simulating speciation and extinction along energy and stability gradients to generate expected patterns of biodiversity for a suite of complementary phylogenetic diversity metrics. Using a time‐calibrated molecular phylogeny for New Zealand marine ray‐finned fishes and a replicated community ecological sampling design, we then modelled these metrics along large‐scale depth and latitude gradients. Our results indicate that energy‐rich shallow waters may be an engine of diversity for percomorphs, but also suggest that recent speciation occurs in ancient fish lineages in the deep sea, hence questioning the role of energy as a key driver of speciation. Despite potentially facing high extinction early in their evolution, ancient phylogenetic lineages specialized for the deep‐sea were likely preserved by environmental stability during the Cenozoic. Furthermore, intermediate depths might be a ‘museum’ (or zone of overlap) for distinct lineages that occur predominantly in either shallow or deep‐sea waters. These intermediate depths (500–900 m) may form a ‘phylogenetic diversity bank’, perhaps providing a refuge during ancient (Mesozoic) extreme anoxic events affecting the deep sea and more recent (Pliocene–Pleistocene) climatic events occurring in shallow ecosystems. Finally, the phylogenetic structures observed in fish communities at intermediate depths suggest other processes might restrict the co‐occurrence of closely related species. Overall, by combining a conceptual framework with models of empirical phylogenetic diversity patterns, our study paves the way for understanding the determinants of biodiversity across the largest habitat on earth.
Elevated levels of somatostatin blunt glucagon counterregulation during hypoglycemia in type 1 diabetes (T1D) and this can be improved using somatostatin receptor 2 (SSTR2) antagonists. Hypoglycemia ...also occurs in late-stage type 2 diabetes (T2D), particularly when insulin therapy is initiated, but the utility of SSTR2 antagonists in ameliorating hypoglycemia in this disease state is unknown. We examined the efficacy of a single-dose of SSTR2 antagonists in a rodent model of T2D.
High-fat fed (HFF), low dose streptozotocin (STZ, 35 mg/kg)-induced T2D and HFF only, nondiabetic (controls-no STZ) rats were treated with the SSTR2 antagonists ZT-01/PRL-2903 or vehicle (
= 9-11/group) 60 min before an insulin tolerance test (ITT; 2-12 U/kg insulin aspart) or an oral glucose tolerance test (OGTT; 2 g/kg glucose via oral gavage) on separate days.
This rodent model of T2D is characterized by higher baseline glucose and HbA1c levels relative to HFF controls. T2D rats also had lower c-peptide levels at baseline and a blunted glucagon counterregulatory response to hypoglycemia when subjected to the ITT. SSTR2 antagonists increased the glucagon response and reduced incidence of hypoglycemia, which was more pronounced with ZT-01 than PRL-2903. ZT-01 treatment in the T2D rats increased glucagon levels above the control response within 60 min of dosing, and values remained elevated during the ITT (glucagon Cmax: 156 ± 50 vs. 77 ± 46 pg/mL,
< 0.01). Hypoglycemia incidence was attenuated with ZT-01 vs. controls (63% vs. 100%) and average time to hypoglycemia onset was also delayed (103.1 ± 24.6 vs. 66.1 ± 23.6 min,
< 0.05). ZT-01 administration at the OGTT onset increased the glucagon response without exacerbating hyperglycemia (2877 ± 806 vs. 2982 ± 781), potentially due to the corresponding increase in c-peptide levels (6251 ± 5463 vs. 14008 ± 5495,
= 0.013).
Treatment with SSTR2 antagonists increases glucagon responses in a rat model of T2D and results in less hypoglycemia exposure. Future studies are required to determine the best dosing periods for chronic SSTR2 antagonism treatment in T2D.
The diadematid sea urchin
Centrostephanus rodgersii
occurs in Australia and New Zealand and has undergone recent southward range extension in Australia as a result of regional warming. Clarifying the ...population genetic structure of this species across its New Zealand range would allow a better understanding of recent and future mechanisms driving range changes in the species. Here, we use microsatellite DNA data to assess connectivity and genetic structure in 385 individuals from 14 locations across the Australian and New Zealand ranges of the species. We detected substantial genetic differentiation among
C. rodgersii
populations from Australia and New Zealand. However, the population from Port Stephens (located north of Newcastle), Australia, strongly clustered with New Zealand samples. This suggests that the New Zealand populations recently originated from this area, likely via larval transport in the Tasman Front flow that arises in this region. The weak population genetic structure and relatively low genetic diversity detected in New Zealand (global
F
st
= 0.0021) relative to Australia (global
F
st
= 0.0339) is consistent with the former population’s inferred history of recent climate-driven expansion. Population-level inbreeding is low in most populations, but were higher in New Zealand (global
F
is
= 0.0833) than in Australia (global
F
is
= 0.0202), suggesting that self-recruitment is playing an increasingly important role in the New Zealand region. Our results suggest that
C. rodgersii
is likely to spread southwards as ocean temperatures increase; therefore, it is crucial that researchers develop a clearer understanding of how New Zealand ecosystems will be reshaped by this species (and others) under climate change.
Biogeographic barriers, some transitory in duration, are likely to have been important contributing factors to modern marine biodiversity in the Indo-Pacific region. One such barrier was the Torres ...Strait land bridge between continental Australia and New Guinea that persisted through much of the late Pleistocene and separated Indian and Pacific Ocean taxa. Here, we examine the patterns of mitochondrial DNA diversity for marine animals with present-day distributions spanning the Torres Strait. Specifically, we investigate whether there are concordant signatures across species, consistent with either vicariance or recent colonization from either ocean basin. We survey four species of reef fishes (
Apogon doederleini
,
Pomacentrus coelestis
,
Dascyllus trimaculatus
, and
Acanthurus triostegus
) for mtDNA cytochrome oxidase 1 and control region variation and contrast these results to previous mtDNA studies in diverse marine animals with similar distributions. We find substantial genetic partitioning (estimated from
F
-statistics and coalescent approaches) between Indian and Pacific Ocean populations for many species, consistent with regional persistence through the late Pleistocene in both ocean basins. The species-specific estimates of genetic divergence, however, vary greatly and for reef fishes we estimate substantially different divergence times among species. It is likely that Indian and Pacific Ocean populations have been isolated for multiple glacial cycles for some species, whereas for other species genetic connections have been more recent. Regional estimates of genetic diversity and directionality of gene flow also vary among species. Thus, there is no apparent consistency among historical patterns across the Torres Strait for these co-distributed marine animals.
Daily increments of Pomacentrus coelestis, an abundant and well‐studied fish, were validated for the life of the fish and depending on the location, age‐maxima were estimated to be 127–160 days on ...reefs separated by tens to hundreds of kilometres on the Great Barrier Reef. This contrasts with congeners and other damselfishes that live for 5 years or more. Otoliths of P. coelestis were thinner and had different patterns of banding when compared with relatively long‐lived congeners. It is suggested that banding patterns in P. coelestis may be related to patterns of maturation and spawning. The consequences of a short life would have a great influence on the population dynamics of this widespread species. Further, the demographics and habitat preferences of this species suggest rapid colonization and establishment of breeding populations that would quickly change the relative abundance of sympatric fishes.
The National Institutes of Health (NIH) Office of Disease Prevention (ODP) sponsors Pathways to Prevention (P2P), an evidence-based scientific workshop program that helps advance prevention research. ...Each P2P workshop is presided over by an independent expert panel and informed by a systematic evidence review, scientific presentations, and public input. Post-workshop activities include collaborating with federal agency partners to develop an action plan for addressing key research gaps. Primary outcomes of P2P workshops include developing a research agenda and creating or enhancing initiatives to implement the agenda. In 2014, ODP partnered with the NIH Pain Consortium and two NIH institutes to convene “The Role of Opioids in the Treatment of Chronic Pain.” This workshop assessed the state-of-the-science on the long-term effectiveness, safety, and harms of opioid use for managing chronic pain. In 2021, ODP initiated an assessment of the outcomes and impact of the Opioids P2P workshop. We applied an evaluation framework and a mixed methods approach encompassing web analytics, bibliometric assessment, grant portfolio analysis, policy assessment, and key informant interviews. Our data showed that the workshop attracted a broad audience, and its published reports had high impact. The workshop also helped inform over 100 new research projects through grants funded by three federal agencies, as well as national legislation and practice guidelines from influential organizations. In sum, the Opioids P2P workshop and follow-up activities have identified gaps in scientific knowledge, informed clinical practice, and catalyzed change on a national level for addressing the prescription opioid crisis.
Cable R&D for the LHC Accelerator Research Program Dietderich, D.R.; Barzi, E.; Ghosh, A.K. ...
IEEE transactions on applied superconductivity,
06/2007, Letnik:
17, Številka:
2
Journal Article, Conference Proceeding
Recenzirano
Future luminosity upgrades for the LHC at CERN will require higher field magnets than those presently being utilized. The US LHC Accelerator Research Program (LARP) is addressing this need with the ...design and fabrication of prototype quadrupole magnets utilizing Nb 3 Sn technology. A part of the R&D effort is the development of suitable cables for the magnet designs being considered by LARP. The cable parameter limits for LARP prototype and production cables are presented. At present the standard strand for LARP is the Restack Rod Processed (RRP) strand being produced by Oxford Superconducting Technologies. The present strand has 54 sub-elements and 53% Cu. An optimal cable for the first generation of LARP quadrupole magnets has a width of 10 mm, thickness of 1.26 mm, and a keystone angle of 1 degree. This work shows that if a strand is properly cabled a nearly degradation-free mechanically-stable cable can be produced.
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