20 research outputs found

    Nest survival in year-round breeding tropical red-capped larks <i>Calandrella cinerea </i>increases with higher nest abundance but decreases with higher invertebrate availability and rainfall

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    Nest survival is critical to breeding in birds and plays an important role in life-history evolution and population dynamics. Studies evaluating the proximate factors involved in explaining nest survival and the resulting temporal patterns are biased in favor of temperate regions. Yet, such studies are especially pertinent to the tropics, where nest predation rates are typically high and environmental conditions often allow for year-round breeding. To tease apart the effects of calendar month and year, population-level breeding activity and environmental conditions, we studied nest survival over a 64-month period in equatorial, year-round breeding red-capped larks Calandrella cinerea in Kenya. We show that daily nest survival rates varied with time, but not in a predictable seasonal fashion among months or consistently among years. We found negative influences of flying invertebrate biomass and rain on nest survival and higher survival of nests when nests were more abundant, which suggests that nest predation resulted from incidental predation. Although an increase in nest predation is often attributed to an increase in nest predators, we suggest that in our study, it may be caused by altered predator activity resulting from increased activity of the primary prey, invertebrates, rather than activity of the red-capped larks. Our results emphasize the need to conduct more studies in Afro-tropical regions because proximate mechanisms explaining nest predation can be different in the unpredictable and highly variable environments of the tropics compared with the relatively predictable seasonal changes found in temperate regions. Such studies will aid in better understanding of the environmental influences on life-history variation and population dynamics in birds

    Politics, 1641-1660

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    Towards coordinated regional multi-satellite InSAR volcano observations:results from the Latin America pilot project

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    Within Latin America, about 319 volcanoes have been active in the Holocene, but 202 of these volcanoes have no seismic, deformation or gas monitoring. Following the 2012 Santorini Report on satellite Earth Observation and Geohazards, the Committee on Earth Observation Satellites (CEOS) developed a 4-year pilot project (2013-2017) to demonstrate how satellite observations can be used to monitor large numbers of volcanoes cost-effectively, particularly in areas with scarce instrumentation and/or difficult access. The pilot aims to improve disaster risk management (DRM) by working directly with the volcano observatories that are governmentally responsible for volcano monitoring as well as with the international space agencies (ESA, CSA, ASI, DLR, JAXA, NASA, CNES). The goal is to make sure that the most useful data are collected at each volcano following the guidelines of the Santorini report that observation frequency is related to volcano activity, and to communicate the results to the local institutions in a timely fashion. Here we highlight how coordinated multi-satellite observations have been used by volcano observatories to monitor volcanoes and respond to crises. Our primary tool is measurements of ground deformation made by Interferometric Synthetic Aperture Radar (InSAR), which have been used in conjunction with other observations to determine the alert level at these volcanoes, served as an independent check on ground sensors, guided the deployment of ground instruments, and aided situational awareness. During this time period, we find 26 volcanoes deforming, including 18 of the 28 volcanoes that erupted – those eruptions without deformation were less than 2 on the VEI scale. Another 7 volcanoes were restless and the volcano observatories requested satellite observations, but no deformation was detected. We describe the lessons learned about the data products and information that are most needed by the volcano observatories in the different countries using information collected by questionnaires. We propose a practical strategy for regional to global satellite volcano monitoring for use by volcano observatories in Latin America and elsewhere to realize the vision of the Santorini report

    Foreign body reaction associated with polyethylene mesh interposition used for treatment of trapeziometacarpal osteoarthritis: Report of 8 cases

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    Purpose To report the incidence of foreign body reactions associated with placement of a polyethylenemesh implant in patients treated with trapiezectomy for trapeziometacarpal osteoarthritis. Methods Between November 2008 and September 2012, 70 hands in 66 adults with stage IV trapeziometacarpal osteoarthritis had a trapiezectomy with interposition of a spacer made of polyethylene terephthalate mesh (Anchois Ligastic, Orthomed SA, St Jeannet, France). Out of these 70 implants, 8 implants (11%) in 8 patients (mean age, 60 y; range, 49e75 y) were removed because of persistent swelling, synovitis, and pain. Results The mean interval between primary and revision surgery was 14 (range, 5e27) months. Histological analysis in all cases showed a foreign body giant cell reaction. Two hands showed bone resorption or carpal bone cysts similar to silicone particle synovitis. The cysts resolved after implant removal and bone grafting. Conclusions In the light of these results and the available literature, we recommend not using this material for interposition in the treatment of osteoarthritis of the trapeziometacarpal joint

    Conservative treatment of thumb base osteoarthritis : A systematic review

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    Purpose To provide a systematic review of randomized controlled trials regarding the conservative treatment of thumb base osteoarthritis (OA). Methods A systematic literature search was conducted in the electronic bibliographic databases Medline (Pubmed) and Embase (both starting year to May 2014) using predetermined criteria for studies on nonoperative treatment of thumb base OA. Results Twenty-three articles fulfilled our inclusion criteria. Systematic evaluation demonstrated the following: (1) Hand therapy can possibly reduce pain. However, owing to the lack of good-quality (randomized controlled) trials with sufficient follow-up time, no proper conclusions can be drawn. (2) Although both steroid and hyaluronate intra-articular injections can provide pain relief, most authors conclude that injection of hyaluronate is more effective. Follow-up is rather short with a maximum of 12 months in 1 study. Furthermore, study comparison is hampered by heterogeneity of study design and outcome parameters. (3) The use of orthoses reduces pain without effect on function, strength, or dexterity. Included studies used various types of orthoses. Follow-up times varied (2 wk-7 y). (4) There is no justification for the use of transdermal steroid delivery. (5) There is insufficient evidence justifying the use of leech therapy. (6) There are no high-level evidence studies specifically evaluating the effect of analgesics and patient education in joint protection in patients with thumb base OA. Conclusions There are only a few high-quality studies addressing the conservative treatment of trapeziometacarpal OA. Available evidence suggests only some effect of orthoses and intra-articular hyaluronate or steroid injections. Type of study/level of evidence Therapeutic II

    Variant CCG and GGC repeats within the CTG expansion dramatically modify mutational dynamics and likely contribute toward unusual symptoms in some myotonic dystrophy type 1 patients

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    Myotonic dystrophy type 1 (DM1) is one of the most variable inherited human disorders. It is characterized by the involvement of multiple tissues and is caused by the expansion of a highly unstable CTG repeat. Variation in disease severity is partially accounted for by the number of CTG repeats inherited. However, the basis of the variable tissue-specific symptoms is unknown. We have determined that an unusual Dutch family co-segregating DM1, Charcot-Marie-Tooth neuropathy, encephalopathic attacks and early hearing loss, carries a complex variant repeat at the DM1 locus. The mutation comprises an expanded CTG tract at the 5'-end and a complex array of CTG repeats interspersed with multiple GGC and CCG repeats at the 3'-end. The complex variant repeat tract at the 3'-end of the array is relatively stable in both blood DNA and the maternal germ line, whilst the 5'-CTG tract remains genetically unstable and prone to expansion. Surprisingly though, even the pure 5'-CTG tract is more stable in blood DNA and the maternal germ line than archetypal DM1 alleles of a similar size. Complex variant repeats were also identified at the 3'-end of the CTG array of [~]3-4% of unrelated DM1 patients. The observed polarity and the stabilizing effect of the variant repeats implicate a cis-acting modifier of mutational dynamics in the 3'-flanking DNA. The presence of such variant repeats very likely contributes toward the unusual symptoms in the Dutch family and additional symptomatic variation in DM1 via affects on both RNA toxicity and somatic instability

    Dark-bellied Brent geese aggregate to cope with increased levels of primary production

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    We report on an aggregative response of Dark-bellied Brent geese to increased productivity of the vegetation during the growing season on agricultural fields on the island of Schiermonnikoog, the Netherlands. Plant standing crop was found to be maintained at low levels in the fields where geese activity focussed, whereas the remainder of the fields escaped herbivore control and developed a high standing crop. This pattern can be explained by a decreased efficiency of grazing in vegetation with a high standing crop. In other words, the functional response of the geese is not monotonically increasing but dome-shaped. As a consequence, continuously grazed swards are more suitable for feeding than temporarily ungrazed swards. We present a model showing that, for a dome-shaped functional response, optimal foraging under increasing primary productivity leads to spatial heterogeneity in standing crop. Beyond a certain threshold value, a further increase in productivity leads to a progressive release of vegetation from herbivore control and to the development of a high standing crop. Interestingly, our model suggests that only in a stable and predictable environment the aggregative behaviour of herbivores is able to maintain the intake rate close to its potential maximum. Misjudgement of patch quality by the herbivore or any other process disrupting the match between local primary production and consumption leads to a less than optimal intake, as suitable vegetation becomes depleted. This has important implications for ecological inferences, such as the prediction of carrying capacities in herbivore-dominated ecosystems.
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