189 research outputs found
Winner, Loser, or Innocent Victim? Has Renewable Energy Performed As Expected?
This study provides an evaluation of the performance of five renewable energy technologies used to generate electricity: biomass, geothermal, solar photovoltaics, solar thermal, and wind. The authors compared the actual performance of these technologies against stated projections that helped shape public policy goals over the last three decades. Their findings document a significant difference between the success of renewable technologies in penetrating the U.S. electricity generation market and in meeting cost-related goals, when compared with historic projections. In general, renewable technologies have failed to meet expectations with respect to market penetration. They have succeeded, however, in meeting or exceeding expectations with respect to their cost. To a significant degree, the difference in performance in meeting projections of penetration and cost stem from the declining price of conventional generation, which constitutes a moving baseline against which renewable technologies have had to compete.
of Airport Landing Slots
Abstract: We investigate the competitive effects of exchanges or sales of airport landing slots. In our model, airlines with potentially asymmetric slot allocations must decide upon which routes to use their landing slots. When all airlines serve the same routes in a slot-constrained Cournot-Nash equilibrium, small changes in slot allocations among airlines do not affect the overall allocation of slots across routes or air fares. In a symmetric equilibrium where slot-holding airlines have the same number of slots, we find that an increase in the number of slot-holding airlines leads to higher social welfare and consumer surplus, although the number of served routes may decline. Under asymmetric slot allocations, larger slot holders serve “thin” demand routes that are not served by smaller slot holders. In this situation, transfers of slots from larger to smaller slot holders increase social welfare and consumer surplus, even though fewer routes may be served. More generally, our results suggest that increases in slot concentration are harmful to consumers and social welfare, although consumers on relatively thin routes may gain air transportation service as a result.
Pre-exposure Prophylaxis (PrEP) for HIV prevention among men who have sex with men (MSM): A scoping review on PrEP service delivery and programming.
Background: Intimate partner violence (IPV) is a risk factor for developmental problems in offspring. Despite a high prevalence of IPV in the UK and elsewhere, the longer-term outcomes of offspring born to exposed mothers remain under-researched. Methods: Population-based cohort study. We assessed IPV prevalence by type and timing for 3,153 mother-child pairs with complete data within our study population and examined associations between IPV and offspring IQ. We used multiple-imputation to evaluate bias due to our exclusion of observations with missing covariate data. Results: Nearly one in five mothers reported IPV during the study period, with 17.6% reporting emotional violence and 6.8% reporting physical violence. Taking into account potential confounders, the IQ scores of children born to mothers exposed to physical violence remained lower than those of maternally unexposed children (full-scale IQ = −2.8 points [95%CI −4.9 to −0.7], verbal IQ = −2.2 [95%CI −4.4 to −0.1], performance IQ = −2.7 [95%CI −5.0 to −0.5]) and odds of below-average intelligence (IQ<90) remained increased for full-scale (OR 1.48 [95%CI 1.03 to 2.14] and performance IQ (OR 1.48 [95%CI 1.08 to 2.04]) but not verbal IQ (OR 1.06 [95%CI 0.69 to 1.64]). Most physical violence occurred postnatally, and relative odds were most substantial when mothers were exposed to violence across pre-/perinatal and postnatal study periods (OR performance IQ<90 = 2.97 [95%CI 1.30 to 6.82]). Conclusions: Maternal exposure to physical IPV is associated with lower offspring IQ at age 8. Associations persisted after adjusting for potential confounders and were driven by violence occurring postnatally
Integra ® Dermal Regeneration Template in Complex Scalp Reconstruction
Background/Objectives: The need for surgical reconstruction of scalp defects following the excision of cutaneous skin cancers is an increasingly common procedure. Particular challenges arise when considering options for reconstruction of large defects not amenable to local skin flap coverage. The use of skin grafts poses the risk of donor site morbidity. This paper investigates the emerging use of Integra®, a synthetic acellular dermal regeneration template, as an alternative or adjunct to skin grafting in scalp reconstruction. Methods: The study presents a retrospective analysis of 101 patients who underwent Integra®-based reconstruction of scalp defects. Demographics, procedure details, complications, need for further surgery, and time to healing were evaluated. Results: The overall success rate of the one-stage Integra®-only procedure was 95%, with a minor complication rate of 30.7%. Anticoagulation medication was identified as an independent risk factor for post-operative infection, while previous head and neck radiotherapy and increased defect depth were associated with the requirement for a second-stage skin graft. Conclusions: These findings support the consideration of Integra® as a safe and viable alternative for both partial and full thickness scalp defects in a select cohort of complex highly co-morbid patients, reducing complications and the need for additional procedures
A Sentinel Population: The public health benefits of monitoring enhanced body builders
There is heightened recognition of the public health implications of anabolic androgenic steroids (AAS) for the use of image and performance enhancement; with increasing evidence of their long-term negative health impacts, the hazards associated with their administration (often via injection), and the variability and unpredictability of their contents. In order to optimise the effects of these drugs, together with strict dietary and training regimes, AAS users typically supplement their use with an expansive and continually evolving range of ancillary drugs. The discovery and subsequent adoption of these drugs by the broader AAS user population is largely dependent upon a minority of social influencers within the bodybuilding community. Pioneering enhanced bodybuilders who self-experiment with a diverse range of image and performance enhancing drugs (IPEDs) and ancillary drugs have been the forerunners in the development of an underground user-led literature, online discussion forums, and were early adopters of internet-facilitated drug markets. Yet the impact of their self-experimentations extends well beyond the enhanced bodybuilding community, particularly in their use of ancillary drugs. Most significantly has been their role in the diffusion of various enhancement and psychoactive drugs to the wider population. Using the theoretical framework of the 'diffusion of innovation' we consider the role that pioneering enhanced bodybuilders have played in the diffusion of various enhancement and psychoactive drugs to the wider population through a focus on three substances –dinitrophenol (DNP), melanotan II and gamma-hydroxybtyrate (GHB). With an increasing range of drugs used by bodybuilders, coupled with an expansion in the use of online forums and online platforms to purchase pharmacological and new psychoactive drugs, we anticipate this trend of diffusion amongst the wider population will continue to flourish. Therefore, we highlight the need for policy makers to monitor emergent trends, not only in the general AAS population but particularly amongst enhanced bodybuilders
The use of anabolic androgenic steroids as a public health issue
In recent years there have been increasing calls for the use of anabolic androgenic steroids (AAS) and associated drugs to be recognized as a public health issue. In the domain of the competitive athlete and professional bodybuilder, recent decades have seen the diffusion of AAS from the hardcore gyms of the 1980s and 1990s to the mainstream exercise and fitness environments of the twenty-first century. Alongside the apparent increases in the use of these drugs, there is a growing evidence base in relation to harms – physical, psychological and (to some extent) social. But is this form of drug use a public health issue? What criteria should we use to make this judgement? What is the available evidence and has our understanding of the issue improved? By drawing on the authors' research in the United Kingdom and the wider international literature this chapter will explore these issues and attempt to answer the fundamental question – is the use of anabolic steroids a public health issue
Exploring and Expanding the Fatty-Acid-Binding Protein Superfamily in Fasciola Species
The liver flukes Fasciola hepatica and F. gigantica infect livestock worldwide and threaten food security with climate change and problematic control measures spreading disease. Fascioliasis is also a food borne disease with up to 17 million humans infected. In the absence of vaccines, treatment depends on Triclabendazole (TCBZ) and over-use has led to widespread resistance, compromising future TCBZ control. Reductionist biology from many laboratories has predicted new therapeutic targets. To this end, the fatty acid binding protein (FABP) superfamily have proposed multi-functional roles, including functions intersecting vaccine and drug therapy, such as immune modulation and anthelmintic sequestration. Research is hindered by a lack of understanding of the full FABP superfamily complement. Although discovery studies predicted FABPs as promising vaccine candidates, it is unclear if uncharacterised FABPs are more relevant for vaccine formulations. We have coupled genome, transcriptome and EST data mining with proteomics and phylogenetics, to reveal a liver fluke FABP superfamily of 7 clades: previously identified clades I-III and newly identified clades IV-VII. All new clade FABPs were analysed using bioinformatics and cloned from both liver flukes. The extended FABP dataset will provide new study tools to research the role of FABPs in parasite biology and as therapy targets
Optical tweezers for the study of microbubble dynamics in ultrasound
2005/2006Optical tweezers enable for non-destructive, contact-free manipulation of ultrasound
contrast agent (UCA) microbubbles, which are used in medical imaging
for enhancing the echogenicity of the blood pool and to quantify organ perfusion.
Understanding the dynamics of ultrasound-driven contrast agent microbubbles
from a fundamental physical standpoint is a first step for exploiting their
acoustical properties and to develop new diagnostic and therapeutic applications.
However, experiments on bubble dynamics presently suffer from a lack of control
on bubble position, because of buoyancy, microstreaming and bubble clustering.
In this respect, optical tweezers can be used to study UCA microbubbles under
controlled and repeatable conditions, by positioning them away from interfaces
and from neighboring bubbles. In addition, an ultra-high speed imaging system
is required to record the dynamics of UCA microbubbles in ultrasound, as their
oscillations occur on the nanoseconds timescale.
In this thesis, optical tweezers and an ultra-high speed camera are integrated
into an experimental setup to control the boundary conditions and record the
oscillations of the microbubbles. Optical tweezers are commonly obtained by focusing
a laser beam through a microscope objective, as the high intensity gradient
in the focal region causes dielectric microparticles to be attracted in the focus.
In the special case of microbubbles, which exhibit a lower refractive index than
the surrounding liquid, the opposite situation arises: they are pushed away from
the region of maximum intensity. Nevertheless, microbubbles can be trapped in
the dark core of a donut-shaped trap, which can be obtained e.g. by focusing
a Laguerre-Gaussian beam. In our setup, a Gaussian beam is converted to a
Laguerre-Gaussian mode by using diffractive optical elements implemented on a
spatial light modulator. This allows to trap and manipulate single or multiple
microbubbles, and to control the distance from interfaces as well as the bubbleto-
bubble distance. The “Brandaris 128” ultra-high speed camera is used, in
combination with the optical tweezers, to recorded the bubble oscillations at a
frame rate of 15 million frames per second.
The influence of a rigid wall on the resonance frequency and oscillation amplitude
was experimentally investigated. An experimental phospholipid-coated
agent (BR-14, Bracco Research S.A., Geneva, Switzerland) was used throughout
the experiments. A resonance frequency curve was recorded for the same
bubble positioned at the wall and at controlled distance from the wall. The experiments
show a drop in the resonance frequency for the bubble close to the
ii Abstract
wall, as expected from the theoretical models. These results are highly relevant
for molecular imaging applications, where the response of targeted microbubbles
needs to be discriminated from that of freely flowing ones. We also quantify the
bubble-to-bubble interaction, in two ways: first, we compare the change of the radial
oscillations of one bubble with and without a neighboring bubble. Second, we
resolve the change in distance between two bubbles during ultrasonic insonation.
This results from an acoustical, generally attractive, interaction force between the
bubbles, termed secondary Bjerknes force. To understand this rich two-bubble
dynamics, we couple a recent single-bubble model, accounting for both gas and
monolayer properties with a model quantifying the mutual interaction of bubbles
in their translation and oscillations.
Experiments where optical tweezers are used as a force sensor to measure the
binding force in an antigen-antibody complex at the single molecule level are also
presented. In the future, the possibility of combining optical micromanipulation
with the force-sensing capabilities of optical tweezers will open the way to a new
class of experiments which will give us a deeper insight into fundamental bubble
phenomena and find direct application to new ultrasound-assisted targeting
strategies.XIX Ciclo197
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