1,925 research outputs found
Potential to use Cyperus rotundus in areas of industrial waste disposal
A fitorremediação é um processo promissor de descontaminação de solos em que a planta é utilizada como um mecanismo de alocação do agente contaminante e indesejável ao sistema tratado. Plantas de Cyperus rotundus, colhidas em área onde ocorreram descartes de resíduos industriais, foram avaliadas utilizando microscopia óptica (MO) e plasma de argônio indutivamente acoplado (ICP-AES). O trabalho objetivou avaliar as alterações causadas pelos poluentes químicos na estrutura morfológica do corpo epígeo de plantas juvenis de C. rotundus e seu potencial fitorremediador em comparação a plantas colhidas em região não poluída do mesmo solo (testemunha). As alterações anatômicas estruturais identificadas demonstram o potencial efeito poluidor dos contaminantes e também sugerem o comportamento hiperacumulador da planta avaliada.Phytoremediation is a promising process of soil decontamination when the plant is used as a mechanism of allocation of the undesirable contaminant agent in the treated system. Samples of Cyperus rotundus collected in a contaminated area with industrial residues were evaluated through optical microscopy and inductively coupled plasma atomic emission spectroscopy (ICP - AES). This work aimed to evaluate the phytoremediator potential and the morphological alterations in young epigeous body of C. rotundus caused by pollutant chemicals in comparison with plants collected in the same soil with no contamination (witness). The observed anatomic alterations compared with the witnesses demonstrated the potential polluting effect of contaminants and also indicated the hyperaccumulating behavior of the analyzed plants.FAPES
Condensate fraction in liquid 4He at zero temperature
We present results of the one-body density matrix (OBDM) and the condensate
fraction n_0 of liquid 4He calculated at zero temperature by means of the Path
Integral Ground State Monte Carlo method. This technique allows to generate a
highly accurate approximation for the ground state wave function Psi_0 in a
totally model-independent way, that depends only on the Hamiltonian of the
system and on the symmetry properties of Psi_0. With this unbiased estimation
of the OBDM, we obtain precise results for the condensate fraction n_0 and the
kinetic energy K of the system. The dependence of n_0 with the pressure shows
an excellent agreement of our results with recent experimental measurements.
Above the melting pressure, overpressurized liquid 4He shows a small condensate
fraction that has dropped to 0.8% at the highest pressure of p = 87 bar.Comment: 12 pages. 4 figures. Accepted for publication on "Journal of Low
Temperature Physics
Study of solid 4He in two dimensions. The issue of zero-point defects and study of confined crystal
Defects are believed to play a fundamental role in the supersolid state of
4He. We report on studies by exact Quantum Monte Carlo (QMC) simulations at
zero temperature of the properties of solid 4He in presence of many vacancies,
up to 30 in two dimensions (2D). In all studied cases the crystalline order is
stable at least as long as the concentration of vacancies is below 2.5%. In the
2D system for a small number, n_v, of vacancies such defects can be identified
in the crystalline lattice and are strongly correlated with an attractive
interaction. On the contrary when n_v~10 vacancies in the relaxed system
disappear and in their place one finds dislocations and a revival of the
Bose-Einstein condensation. Thus, should zero-point motion defects be present
in solid 4He, such defects would be dislocations and not vacancies, at least in
2D. In order to avoid using periodic boundary conditions we have studied the
exact ground state of solid 4He confined in a circular region by an external
potential. We find that defects tend to be localized in an interfacial region
of width of about 15 A. Our computation allows to put as upper bound limit to
zero--point defects the concentration 0.003 in the 2D system close to melting
density.Comment: 17 pages, accepted for publication in J. Low Temp. Phys., Special
Issue on Supersolid
New insights in the management of Hepatocellular Adenoma
Hepatocellular adenoma (HCA) are benign liver tumours that may be complicated by haemorrhage or malignant transformation to hepatocellular carcinoma. Epidemiological data are fairly outdated, but it is likely to assume that the incidence has increased over the past decades as HCA are more often incidentally found due to the more widespread use of imaging techniques and the increased incidence of obesity. Various molecular subgroups have been described. Each of these molecular subgroups are defined by specific gene mutations and pathway activations. Additionally, they are all related to specific risk factors and show a various biological behaviour. These molecular subgroups may be identified using immunohistochemistry and molecular characterization. Contrast-enhanced MRI is the recommended imaging modality to analyse patients with suspected hepatocellular adenoma allowing to determine the subtype in up to 80%. Surgical resection remains to be the golden standard in treating HCA, although resection is deemed unnecessary in a large number of cases, as studies have shown that the majority of HCA will regress over time without complications such as haemorrhage or malignant transformation occurring. It is preferable to treat patients with suspected HCA in high volume centres with combined expertise of liver surgeons, hepatologists, radiologists and (molecular) pathologists
Spectrum of the Y=2 Pentaquarks
By assuming a mass formula for the spectrum of the Y=2 pentaquarks, where the
chromo-magnetic interaction plays a main role, and identifying the lightest
state with the Theta^+(1540), we predict a spectrum in good agreement with the
few I=0 and I=1 candidates proposed in the past.Comment: 12 pages, 4 figures, LaTe
Current-Induced Torques in Magnetic Metals: Beyond Spin Transfer
Current-induced torques on ferromagnetic nanoparticles and on domain walls in
ferromagnetic nanowires are normally understood in terms of transfer of
conserved spin angular momentum between spin-polarized currents and the
magnetic condensate. In a series of recent articles we have discussed a
microscopic picture of current-induced torques in which they are viewed as
following from exchange fields produced by the misaligned spins of current
carrying quasiparticles. This picture has the advantage that it can be applied
to systems in which spin is not approximately conserved. More importantly, this
point of view makes it clear that current-induced torques can also act on the
order parameter of an antiferromagnetic metal, even though this quantity is not
related to total spin. In this informal and intentionally provocative review we
explain this picture and discuss its application to antiferromagnets.Comment: 5 figures, to appear in Journal of Magnetism and
The SWAP EUV Imaging Telescope Part I: Instrument Overview and Pre-Flight Testing
The Sun Watcher with Active Pixels and Image Processing (SWAP) is an EUV
solar telescope on board ESA's Project for Onboard Autonomy 2 (PROBA2) mission
launched on 2 November 2009. SWAP has a spectral bandpass centered on 17.4 nm
and provides images of the low solar corona over a 54x54 arcmin field-of-view
with 3.2 arcsec pixels and an imaging cadence of about two minutes. SWAP is
designed to monitor all space-weather-relevant events and features in the low
solar corona. Given the limited resources of the PROBA2 microsatellite, the
SWAP telescope is designed with various innovative technologies, including an
off-axis optical design and a CMOS-APS detector. This article provides
reference documentation for users of the SWAP image data.Comment: 26 pages, 9 figures, 1 movi
A community jury study exploring the public acceptability of using risk stratification to determine eligibility for cancer screening
Introduction
Using risk stratification to determine eligibility for cancer screening is likely to improve the efficiency of screening programmes by targeting resources towards those most likely to benefit. We aimed to explore the implications of this approach from a societal perspective by understanding public views on the most acceptable stratification strategies.
Methods
We conducted three online community juries with 9 or 10 participants in each. Participants were purposefully sampled by age (40–79 years), sex, ethnicity, social grade and English region. On the first day, participants were informed of the potential benefits and harms of cancer screening and the implications of different ways of introducing stratification using scenarios based on phenotypic and genetic risk scores. On the second day, participants deliberated to reach a verdict on the research question, ‘Which approach(es) to inviting people to screening are acceptable, and under what circumstances?’ Deliberations and feedback were recorded and analysed using thematic analysis.
Results
Across the juries, the principle of risk stratification was generally considered to be an acceptable approach for determining eligibility for screening. Disregarding increasing capacity, the participants considered it to enable efficient resource allocation to high-risk individuals and could see how it might help to save lives. However, there were concerns regarding fair implementation, particularly how the risk assessment would be performed at scale and how people at low risk would be managed. Some favoured using the most accurate risk prediction model whereas others thought that certain risk factors should be prioritized (particularly factors considered as non-modifiable and relatively stable, such as genetics and family history). Transparently justifying the programme and public education about cancer risk emerged as important contributors to acceptability.
Conclusion
Using risk stratification to determine eligibility for cancer screening was acceptable to informed members of the public, particularly if it included risk factors they considered fair and when communicated transparently.
Patient or Public Contribution
Two patient and public involvement representatives were involved throughout this study. They were not involved in synthesizing the results but contributed to producing study materials, co-facilitated the community juries and commented on the interpretation of the findings and final report
Calorimetric and transport investigations of CePd_{2+x}Ge_{2-x} (x=0 and 0.02) up to 22 GPa
The influence of pressure on the magnetically ordered CePd_{2.02}Ge_{1.98}
has been investigated by a combined measurement of electrical resistivity,
, and ac-calorimetry, C(T), for temperatures in the range 0.3 K<T<10 K
and pressures, p, up to 22 GPa. Simultaneously CePd_2Ge_2 has been examined by
down to 40 mK. In CePd_{2.02}Ge_{1.98} and CePd_2Ge_2 the magnetic
order is suppressed at a critical pressure p_c=11.0 GPa and p_c=13.8 GPa,
respectively. In the case of CePd_{2.02}Ge_{1.98} not only the temperature
coefficient of , A, indicates the loss of magnetic order but also the
ac-signal recorded at low temperature. The residual
resistivity is extremely pressure sensitive and passes through a maximum and
then a minimum in the vicinity of p_c. The (T,p) phase diagram and the
A(p)-dependence of both compounds can be qualitatively understood in terms of a
pressure-tuned competition between magnetic order and the Kondo effect
according to the Doniach picture. The temperature-volume (T,V) phase diagram of
CePd_2Ge_2 combined with that of CePd_2Si_2 shows that in stoichiometric
compounds mainly the change of interatomic distances influences the exchange
interaction. It will be argued that in contrast to this the much lower
p_c-value of CePd_{2.02}Ge_{1.98} is caused by an enhanced hybridization
between 4f and conduction electrons.Comment: 9 pages, 7 figure
Zero-point vacancies in quantum solids
A Jastrow wave function (JWF) and a shadow wave function (SWF) describe a
quantum solid with Bose--Einstein condensate; i.e. a supersolid. It is known
that both JWF and SWF describe a quantum solid with also a finite equilibrium
concentration of vacancies x_v. We outline a route for estimating x_v by
exploiting the existing formal equivalence between the absolute square of the
ground state wave function and the Boltzmann weight of a classical solid. We
compute x_v for the quantum solids described by JWF and SWF employing very
accurate numerical techniques. For JWF we find a very small value for the zero
point vacancy concentration, x_v=(1.4\pm0.1) x 10^-6. For SWF, which presently
gives the best variational description of solid 4He, we find the significantly
larger value x_v=(1.4\pm0.1) x 10^-3 at a density close to melting. We also
study two and three vacancies. We find that there is a strong short range
attraction but the vacancies do not form a bound state.Comment: 19 pages, submitted to J. Low Temp. Phy
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