1,338 research outputs found
Industrial precipitation of zirconyl chloride: the effect of pH and solution concentration on calcination of zirconia
In situ and ex situ X-ray diffraction, and transmission electron microscopy were used to investigate thecalcination of four samples of zirconia manufactured using two different zirconia reactant solution concentrations (0.81M and 1.62M) with precipitation carried out at pH 3 and 12. The calcinations wereinvestigated over the temperature range from room temperature to 1000"C. It was found that varyingthe precipitation conditions resulted in differing calcination routes; it is believed that variations in particlesize and initial degree of hydration are responsible for these differences. It was also found that theinitial phase produced after calcination was tetragonal zirconia, which underwent a process of crystallitegrowth to a size of # 30nm before transformation from tetragonal to monoclinic
Lacunar-canalicular network in femoral cortical bone is reduced in aged women and is predominantly due to a loss of canalicular porosity
The lacunar-canalicular network (LCN) of bone contains osteocytes and their dendritic extensions, which allow for intercellular communication, and are believed to serve as the mechanosensors that coordinate the processes of bone modeling and remodeling. Imbalances in remodeling, for example, are linked to bone disease, including fragility associated with aging. We have reported that there is a reduction in scale for one component of the LCN, osteocyte lacunar volume, across the human lifespan in females. In the present study, we explore the hypothesis that canalicular porosity also declines with age. To visualize the LCN and to determine how its components are altered with aging, we examined samples from young (age: 20-23 y; n = 5) and aged (age: 70-86 y; n = 6) healthy women donors utilizing a fluorescent labelling technique in combination with confocal laser scanning microscopy. A large cross-sectional area of cortical bone spanning the endosteal to periosteal surfaces from the anterior proximal femoral shaft was examined in order to account for potential trans-cortical variation in the LCN. Overall, we found that LCN areal fraction was reduced by 40.6% in the samples from aged women. This reduction was due, in part, to a reduction in lacunar density (21.4% decline in lacunae number per given area of bone), but much more so due to a 44.6% decline in canalicular areal fraction. While the areal fraction of larger vascular canals was higher in endosteal vs. periosteal regions for both age groups, no regional differences were observed in the areal fractions of the LCN and its components for either age group. Our data indicate that the LCN is diminished in aged women, and is largely due to a decline in the canalicular areal fraction, and that, unlike vascular canal porosity, this diminished LCN is uniform across the cortex
Legal coercion, respect & reason-responsive agency
Legal coercion seems morally problematic because it is susceptible to the Hegelian objection that it fails to respect individuals in a way that is âdue to them as menâ. But in what sense does legal coercion fail to do so? And what are the grounds for this requirement to respect? This paper is an attempt to answer these questions. It argues that (a) legal coercion fails to respect individuals as reason-responsive agents; and (b) individuals ought to be respected as such in virtue of the fact that they are human beings. Thus it is in this sense that legal coercion fails to treat individuals with the kind of respect âdue to them as menâ.The Leverhulme Trust (ECF-2012-032); AHRC (AH/H015655/1
Multilocus sequence typing of pathogenic treponemes isolated from cloven-hoofed animals and comparison to treponemes isolated from humans
Treponema species are implicated in many diseases of humans and animals. Digital dermatitis (DD) treponemes are reported to cause severe lesions in cattle, sheep, pigs, goats, and wild elk, causing substantial global animal welfare issues and economic losses. The fastidiousness of these spirochetes has previously precluded studies investigating within-phylogroup genetic diversity. An archive of treponemes that we isolated enabled multilocus sequence typing to quantify the diversity and population structure of DD treponemes. Isolates (n = 121) were obtained from different animal hosts in nine countries on three continents. The analyses herein of currently isolated DD treponemes at seven housekeeping gene loci confirm the classification of the three previously designated phylogroups: the Treponema medium, Treponema phagedenis, and Treponema pedis phylogroups. Sequence analysis of seven DD treponeme housekeeping genes revealed a generally low level of diversity among the strains within each phylogroup, removing the need for the previously used "-like" suffix. Surprisingly, all isolates within each phylogroup clustered together, regardless of host or geographic origin, suggesting that the same sequence types (STs) can infect different animals. Some STs were derived from multiple animals from the same farm, highlighting probable within-farm transmissions. Several STs infected multiple hosts from similar geographic regions, identifying probable frequent between-host transmissions. Interestingly, T. pedis appears to be evolving more quickly than the T. medium or T. phagedenis DD treponeme phylogroup, by forming two unique ST complexes. The lack of phylogenetic discrimination between treponemes isolated from different hosts or geographic regions substantially contrasts with the data for other clinically relevant spirochetes
A Hybrid Global Minimization Scheme for Accurate Source Localization in Sensor Networks
We consider the localization problem of multiple wideband sources in a
multi-path environment by coherently taking into account the attenuation
characteristics and the time delays in the reception of the signal. Our
proposed method leaves the space for unavailability of an accurate signal
attenuation model in the environment by considering the model as an unknown
function with reasonable prior assumptions about its functional space. Such
approach is capable of enhancing the localization performance compared to only
utilizing the signal attenuation information or the time delays. In this paper,
the localization problem is modeled as a cost function in terms of the source
locations, attenuation model parameters and the multi-path parameters. To
globally perform the minimization, we propose a hybrid algorithm combining the
differential evolution algorithm with the Levenberg-Marquardt algorithm.
Besides the proposed combination of optimization schemes, supporting the
technical details such as closed forms of cost function sensitivity matrices
are provided. Finally, the validity of the proposed method is examined in
several localization scenarios, taking into account the noise in the
environment, the multi-path phenomenon and considering the sensors not being
synchronized
How Do Aspirations Matter?
This paper explores the complex roles of aspirations in relation to human
development, drawing upon the capability approach. The paper examines the
notion of feasibility of aspirations and the impact feasibility judgements have on
aspiration formation and aspiration realisation, in terms of both capabilities and
functionings. In particular this paper extends existing theory by building on
Hartâs (2004, 2012) dynamic multi-dimensional model of aspiration and Hartâs
(2012) aspiration set. The theorization builds on empirical work, undertaken in
the UK, seeking to understand pupilâs aspirations on leaving school and college at
age 17-19 as well as reviewing wider empirical and theoretical literature in this
field. The discussion contributes to capability theory by extending
understanding regarding first, the way that aspirations are connected to
capabilities and functionings, secondly, the processes by which aspirations are
converted into capabilities and thirdly, how certain capabilities become
functionings. The paper reflects on the criteria that inform choices about the
cultivation and selection of different aspirations on individual and collective
bases. )n concluding the paper the question of âhow do aspirations matter?â is
addressed. Ultimately an argument is made for the need to âreclaimâ a rich
multi-dimensional concept of aspiration in order to pursue human development
and flourishing for all
Magnetic fields and differential rotation on the pre-main sequence I: The early-G star HD 141943 - brightness and magnetic topologies
Spectroscopic and spectropolarimetric observations of the pre-main sequence
early-G star HD 141943 were obtained at four observing epochs (in 2006, 2007,
2009 and 2010). The observations were undertaken at the 3.9-m Anglo-Australian
Telescope using the UCLES echelle spectrograph and the SEMPOL
spectropolarimeter visitor instrument. Brightness and surface magnetic field
topologies were reconstructed for the star using the technique of least-squares
deconvolution to increase the signal-to-noise of the data.
The reconstructed brightness maps show that HD 141943 had a weak polar spot
and a significant amount of low latitude features, with little change in the
latitude distribution of the spots over the 4 years of observations. The
surface magnetic field was reconstructed at three of the epochs from a high
order (l <= 30) spherical harmonic expansion of the spectropolarimetric
observations. The reconstructed magnetic topologies show that in 2007 and 2010
the surface magnetic field was reasonably balanced between poloidal and
toroidal components. However we find tentative evidence of a change in the
poloidal/toroidal ratio in 2009 with the poloidal component becoming more
dominant. At all epochs the radial magnetic field is predominantly
non-axisymmetric while the azimuthal field is predominantly axisymmetric with a
ring of positive azimuthal field around the pole similar to that seen on other
active stars.Comment: 18 pages, 17 figures, accepted by MNRA
Exploring concepts of health with male prisoners in three category-C English prisons
Lay understandings of health and illness have a well established track record and a plethora of research now exists which has examined these issues. However, there is a dearth of research which has examined the perspectives of those who are imprisoned. This paper attempts to address this research gap. The paper is timely given that calls have been made to examine lay perspectives in different geographical locations and a need to re-examine health promotion approaches in prison settings. Qualitative data from thirty-six male sentenced prisoners from three prisons in England were collected. The data was analysed in accordance with Attride-Stirling's (2001) thematic network approach. Although the men's perceptions of health were broadly similar to the general population, some interesting findings emerged which were directly related to prison life and its associated structures. These included access to the outdoors and time out of their prison cell, as well as maintaining relationships with family members through visits. The paper proposes that prisoners' lay views should be given higher priority given that prison health has traditionally been associated with medical treatment and the bio-medical paradigm more generally. It also suggests that in order to fulfil the World Health Organization's (WHO) vision of viewing prisons as health promoting settings, lay views should be recognised to shape future health promotion policy and practice
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Mitigation of Moral Hazard and Adverse Selection in Venture Capital Financing: The Influence of the Countryâs Institutional Setting
A venture capitalist (VC) needs to trade off benefits and costs when attempting to mitigate agency problems in their investor-investee relationship. We argue that signals of ventures complement the VCâs capacity to screen and conduct a due diligence during the pre-investment phase, but its attractiveness may diminish in institutional settings supporting greater transparency. Similarly, whereas a VC may opt for contractual covenants to curb potential opportunism by ventures in the post-investment phase, this may only be effective in settings supportive of shareholder rights enforcement. Using an international sample of VC contracts, our study finds broad support for these conjectures. It delineates theoretical and practical implications for how investors can best deploy their capital in different institutional settings whilst nurturing their relationships with entrepreneurs
The Weddell Gyre, Southern Ocean: present knowledge and future challenges
The Weddell Gyre (WG) is one of the main oceanographic features of the Southern Ocean south of the Antarctic Circumpolar Current which plays an influential role in global ocean circulation as well as gas exchange with the atmosphere. We review the stateâofâthe art knowledge concerning the WG from an interdisciplinary perspective, uncovering critical aspects needed to understand this system's role in shaping the future evolution of oceanic heat and carbon uptake over the next decades. The main limitations in our knowledge are related to the conditions in this extreme and remote environment, where the polar night, very low air temperatures and presence of sea ice yearâround hamper field and remotely sensed measurements. We highlight the importance of winter and underâice conditions in the southern WG, the role that new technology will play to overcome presentâday sampling limitations, the importance of the WG connectivity to the lowâlatitude oceans and atmosphere, and the expected intensification of the WG circulation as the westerly winds intensify. Greater international cooperation is needed to define key sampling locations that can be visited by any research vessel in the region. Existing transects sampled since the 1980s along the Prime Meridian and along an EastâWest section at ~62°S should be maintained with regularity to provide answers to the relevant questions. This approach will provide longâterm data to determine trends and will improve representation of processes for regional, Antarcticâwide and global modeling efforts â thereby enhancing predictions of the WG in global ocean circulation and climate
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