176 research outputs found
Integration of bow-tie plasmonic nano-antennas on tapered fibers
FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPIn this article, a new and flexible approach to control the electric field enhancement of bow-tie nano-antennas by integrating them on the lateral of a tapered optical fiber is proposed. The device is driven by a Q-switched laser and the performance of a fabricated nano-antenna in a quartz slide is tested by a Surface Enhanced Raman Scattering (SERS) experiment. A refractive index sensing experiment is also performed and a sensitivity of (240 +/- 30) nm/RIU is found in the 1.33-1.35 index range.25889868996FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP2014/50632-6The Asian Office of Aerospace Research and Development (AOARD US Air Force FA2386-15-1-4084); Australian Research Council (ARC LP160100253); and Sao Paulo Research Foundation (FAPESP) (#2014/50632-6)
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Futures trading, spot price volatility and market efficiency: evidence from European real estate securities futures
In 2007 futures contracts were introduced based upon the listed real estate market in Europe. Following their launch they have received increasing attention from property investors, however, few studies have considered the impact their introduction has had. This study considers two key elements. Firstly, a traditional Generalized Autoregressive Conditional Heteroskedasticity (GARCH) model, the approach of Bessembinder & Seguin (1992) and the Gray’s (1996) Markov-switching-GARCH model are used to examine the impact of futures trading on the European real estate securities market. The results show that futures trading did not destabilize the underlying listed market. Importantly, the results also reveal that the introduction of a futures market has improved the speed and quality of information flowing to the spot market. Secondly, we assess the hedging effectiveness of the contracts using two alternative strategies (naïve and Ordinary Least Squares models). The empirical results also show that the contracts are effective hedging instruments, leading to a reduction in risk of 64 %
Laser-Assisted In Vitro Fertilization Facilitates Fertilization of Vitrified-Warmed C57BL/6 Mouse Oocytes with Fresh and Frozen-Thawed Spermatozoa, Producing Live Pups
The utility of cryopreserved mouse gametes for reproduction of transgenic mice depends on development of assisted reproductive technologies, including vitrification of unfertilized mouse oocytes. Due to hardening of the zona pellucida, spermatozoa are often unable to penetrate vitrified-warmed (V-W) oocytes. Laser-assisted in vitro fertilization (LAIVF) facilitates fertilization by allowing easier penetration of spermatozoa through a perforation in the zona. We investigated the efficiency of V-W C57BL/6NTac oocytes drilled by the XYClone laser, compared to fresh oocytes. By using DAP213 for cryoprotection, 83% (1,470/1,762) of vitrified oocytes were recovered after warming and 78% were viable. Four groups were evaluated for two-cell embryo and live offspring efficiency: 1) LAIVF using V-W oocytes, 2) LAIVF using fresh oocytes, 3) conventional IVF using V-W oocytes and 4) conventional IVF using fresh oocytes. First, the groups were tested using fresh C57BL/6NTac spermatozoa (74% motile, 15 million/ml). LAIVF markedly improved the two-cell embryo efficiency using both V-W (76%, 229/298) and fresh oocytes (69%, 135/197), compared to conventional IVF (7%, 12/182; 6%, 14/235, respectively). Then, frozen-thawed C57BL/6NTac spermatozoa (35% motile, 15 million/ml) were used and LAIVF was again found to enhance fertilization efficiency, with two-cell embryo rates of 87% (298/343) using V-W oocytes (P<0.05, compared to fresh spermatozoa), and 73% (195/266) using fresh oocytes. Conventional IVF with frozen-thawed spermatozoa using V-W (6%, 10/168) and fresh (5%, 15/323) oocytes produced few two-cell embryos. Although live offspring efficiency following embryo transfer was greater with conventional IVF (35%, 18/51; LAIVF: 6%, 50/784), advantage was seen with LAIVF in live offspring obtained from total oocytes (5%, 50/1,010; conventional IVF: 2%, 18/908). Our results demonstrated that zona-drilled V-W mouse oocytes can be used for IVF procedures using both fresh and frozen-thawed spermatozoa, producing live pups. The ability to cryopreserve mouse gametes for LAIVF may facilitate management of large-scale transgenic mouse production facilities.National Institutes of Health (U.S.) (NIH National Research Service Award (T32-RR070036))National Institutes of Health (U.S.) (NIH National Cancer Institute Program Project (P01CA10451)
Species Interactions Alter Evolutionary Responses to a Novel Environment
Adaptation to a novel environment is altered by the presence of co-occurring species. Species in diverse communities evolved complementary resource use, which altered the functioning of the experimental ecosystems
Climatic and topographic changes since the Miocene influenced the diversification and biogeography of the tent tortoise (Psammobates tentorius) species complex in Southern Africa
Background: Climatic and topographic changes function as key drivers in shaping genetic structure and cladogenic
radiation in many organisms. Southern Africa has an exceptionally diverse tortoise fauna, harbouring one-third of
the world’s tortoise genera. The distribution of Psammobates tentorius (Kuhl, 1820) covers two of the 25 biodiversity
hotspots in the world, the Succulent Karoo and Cape Floristic Region. The highly diverged P. tentorius represents an
excellent model species for exploring biogeographic and radiation patterns of reptiles in Southern Africa.
Results: We investigated genetic structure and radiation patterns against temporal and spatial dimensions since the
Miocene in the Psammobates tentorius species complex, using multiple types of DNA markers and niche modelling
analyses. Cladogenesis in P. tentorius started in the late Miocene (11.63–5.33 Ma) when populations dispersed from
north to south to form two geographically isolated groups. The northern group diverged into a clade north of the
Orange River (OR), followed by the splitting of the group south of the OR into a western and an interior clade. The
latter divergence corresponded to the intensifcation of the cold Benguela current, which caused western aridifcation
and rainfall seasonality. In the south, tectonic uplift and subsequent exhumation, together with climatic fuctuations
seemed responsible for radiations among the four southern clades since the late Miocene. We found that each clade
occurred in a habitat shaped by diferent climatic parameters, and that the niches difered substantially among the
clades of the northern group but were similar among clades of the southern group.
Conclusion: Climatic shifts, and biome and geographic changes were possibly the three major driving forces shaping cladogenesis and genetic structure in Southern African tortoise species. Our results revealed that the cladogenesis
of the P. tentorius species complex was probably shaped by environmental cooling, biome shifts and topographic
uplift in Southern Africa since the late Miocene. The Last Glacial Maximum (LGM) may have impacted the distribution
of P. tentorius substantially. We found the taxonomic diversify of the P. tentorius species complex to be highest in the
Greater Cape Floristic Region. All seven clades discovered warrant conservation attention, particularly Ptt-B–Ptr, Ptt-A
and Pv-
Silicon optical modulators
Optical technology is poised to revolutionize short-reach interconnects. The leading candidate technology is silicon photonics, and the workhorse of such an interconnect is the optical modulator. Modulators have been improved dramatically in recent years, with a notable increase in bandwidth from the megahertz to the multigigahertz regime in just over half a decade. However, the demands of optical interconnects are significant, and many questions remain unanswered as to whether silicon can meet the required performance metrics. Minimizing metrics such as the device footprint and energy requirement per bit, while also maximizing bandwidth and modulation depth, is non-trivial. All of this must be achieved within an acceptable thermal tolerance and optical spectral width using CMOS-compatible fabrication processes. This Review discusses the techniques that have been (and will continue to be) used to implement silicon optical modulators, as well as providing an outlook for these devices and the candidate solutions of the future
Treatments for people who use anabolic androgenic steroids: a scoping review.
BACKGROUND: A growing body of evidence suggests that anabolic androgenic steroids (AAS) are used globally by a diverse population with varying motivations. Evidence has increased greatly in recent years to support understanding of this form of substance use and the associated health harms, but there remains little evidence regarding interventions to support cessation and treat the consequences of use. In this scoping review, we identify and describe what is known about interventions that aim to support and achieve cessation of AAS, and treat and prevent associated health problems. METHODS: A comprehensive search strategy was developed in four bibliographic databases, supported by an iterative citation searching process to identify eligible studies. Studies of any psychological or medical treatment interventions delivered in response to non-prescribed use of AAS or an associated harm in any setting were eligible. RESULTS: In total, 109 eligible studies were identified, which included case reports representing a diverse range of disciplines and sources. Studies predominantly focussed on treatments for harms associated with AAS use, with scant evidence on interventions to support cessation of AAS use or responding to dependence. The types of conditions requiring treatment included psychiatric, neuroendocrine, hepatic, kidney, cardiovascular, musculoskeletal and infectious. There was limited evidence of engagement with users or delivery of psychosocial interventions as part of treatment for any condition, and of harm reduction interventions initiated alongside, or following, treatment. Findings were limited throughout by the case report study designs and limited information was provided. CONCLUSION: This scoping review indicates that while a range of case reports describe treatments provided to AAS users, there is scarce evidence on treating dependence, managing withdrawal, or initiating behaviour change in users in any settings. Evidence is urgently required to support the development of effective services for users and of evidence-based guidance and interventions to respond to users in a range of healthcare settings. More consistent reporting in articles of whether engagement or assessment relating to AAS was initiated, and publication within broader health- or drug-related journals, will support development of the evidence base
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