4,490 research outputs found
Anomalous coupling between topological defects and curvature
We investigate a counterintuitive geometric interaction between defects and
curvature in thin layers of superfluids, superconductors and liquid crystals
deposited on curved surfaces. Each defect feels a geometric potential whose
functional form is determined only by the shape of the surface, but whose sign
and strength depend on the transformation properties of the order parameter.
For superfluids and superconductors, the strength of this interaction is
proportional to the square of the charge and causes all defects to be repelled
(attracted) by regions of positive (negative) Gaussian curvature. For liquid
crystals in the one elastic constant approximation, charges between 0 and
are attracted by regions of positive curvature while all other charges
are repelled.Comment: 5 pages, 4 figures, minor changes, accepted for publication in Phys.
Rev. Let
Assessment of biological kinetics in a conventional municipal WWTP by means of the oxygen uptake rate method
Pollution control of surface water bodies requires stringent checks on wastewater treatment plants performances. The satisfactory operation of biological treatment, commonly performed by means of activated sludge processes, requires a number of controlling and monitoring procedures. Suitable respirometric techniques for the determination of the kinetic parameters that regulate biological processes have been implemented in order to achieve this aim. This paper describes the results of an experimental research carried out in a conventional Italian municipal wastewater treatment plant. Particularly, the research has been finalized to both evaluate the biological process for the removal of biodegradable pollutants, such as carbonaceous substrates and ammonia nitrogen, and to collect data in order to evaluate a possible plant upgrade. Heterotrophic and autotrophic biomass kinetic parameters have been examined using respirometric techniques based on oxygen uptake measurements. The research performed makes a valuable contribution toward verifying the reliability of the values proposed in the literature for some kinetic parameters, which have been commonly used for a long time
Proof of the thermodynamical stability of the E' center in SiO2
The E' center is a paradigmatic radiation-induced defect in SiO2 whose
peculiar EPR and hyperfine activity has been known since over 40 years. This
center has been traditionally identified with a distorted, positively-charged
oxygen vacancy V_O+. However, no direct proof of the stability of this defect
has ever been provided, so that its identification is still strongly
incomplete. Here we prove directly that distorted V_O+ is metastable and that
it satisfies the key requirements for its identification as E', such as thermal
and optical response, and activation-deactivation mechanisms.Comment: RevTeX 4 pages, 2 figure
Detection of Brucella abortus DNA and RNA in different stages of development of the sucking louse Haematopinus tuberculatus
Background: Brucellosis is considered the world’s most widespread zoonotic infection. It causes abortion and
sterility in livestock leading to serious economic losses and has even more serious medical impact in humans, since
it can be a trigger to more than 500,000 infections per year worldwide. The aim of this study was to evaluate the
role of Haematopinus tuberculatus, a louse that can parasitize several ruminants, as a new host of brucellosis. Louse
specimens were collected from seropositive and seronegative water buffaloes and divided in 3 developmental
stages: adults, nymphs and nits. All samples were separately screened for Brucella spp. DNA and RNA detection by
Real Time PCR. In particular, primers and probes potentially targeting the 16S rRNA and the Brucella Cell Surface
31 kDalton Protein (bcsp31) genes were used for Real Time PCR and buffalo β actin was used as a housekeeping
gene to quantify host DNA in the sample. A known amount of B. abortus purified DNA was utilized for standard
curve preparation and the target DNA amount was divided by the housekeeping gene amount to obtain a
normalized target value. A further molecular characterization was performed for Brucella strain typing and
genotyping by the Bruce-ladder, AMOS-PCR and MLVA assays. Data were statistically analysed by ANOVA.
Results: Brucella abortus DNA and RNA were detected in all developmental stages of the louse, suggesting the
presence of viable bacteria. Data obtained by MLVA characterization support this finding, since the strains present
in animals and the relative parasites were not always identical, suggesting bacterial replication. Furthermore, the
detection of Brucella DNA and RNA in nits samples demonstrate, for the first time, a trans-ovarial transmission of the
bacterium into the louse.
Conclusions: These findings identified H. tuberculatus as a new host of brucellosis. Further studies are needed to
establish the role of this louse in the epidemiology of the disease, such as vector or reservoir
Charged particle's flux measurement from PMMA irradiated by 80 MeV/u carbon ion beam
Hadrontherapy is an emerging technique in cancer therapy that uses beams of
charged particles. To meet the improved capability of hadrontherapy in matching
the dose release with the cancer position, new dose monitoring techniques need
to be developed and introduced into clinical use. The measurement of the fluxes
of the secondary particles produced by the hadron beam is of fundamental
importance in the design of any dose monitoring device and is eagerly needed to
tune Monte Carlo simulations. We report the measurements done with charged
secondary particles produced from the interaction of a 80 MeV/u fully stripped
carbon ion beam at the INFN Laboratori Nazionali del Sud, Catania, with a
Poly-methyl methacrylate target. Charged secondary particles, produced at
90 with respect to the beam axis, have been tracked with a drift
chamber, while their energy and time of flight has been measured by means of a
LYSO scintillator. Secondary protons have been identified exploiting the energy
and time of flight information, and their emission region has been
reconstructed backtracking from the drift chamber to the target. Moreover a
position scan of the target indicates that the reconstructed emission region
follows the movement of the expected Bragg peak position. Exploting the
reconstruction of the emission region, an accuracy on the Bragg peak
determination in the submillimeter range has been obtained. The measured
differential production rate for protons produced with 83 MeV and emitted at 90 with respect to the beam line is: .Comment: 13 pages, 9 figure
Inhibitory effect of quercetin on OVCA 433 cells and presence of type II oestrogen binding sites in primary ovarian tumours and cultured cells.
We investigated the effect of the flavonoid quercetin (Q) on the proliferation of the ovarian cancer cell line OVCA 433. Growth experiments demonstrated that Q exerted a reversible dose-dependent inhibition of cell proliferation in the range of concentrations between 10 nM and 10 microM. Two other flavonoids tested, rutin and hesperidin, were ineffective in inhibiting cell growth. Cell cycle analysis showed that the growth inhibitory effect of Q was due to a blocking effect in the GO/G1 phase. Using a whole cell assay with (6.7-3H) oestradiol (3H-E2) as tracer we demonstrated that OVCA 433 cells contain type II oestrogen binding sites (type II EBS). Competition analysis showed that Q competed for 3H-E2 binding to type II EBS while both rutin and hesperidin did not. Appreciable amounts of type II EBS were also detected in seven primary ovarian tumours. Our results suggest that Q may regulate ovarian cancer cell growth through a mechanism involving a binding interaction with type II EBS. This mechanism could also be active in vivo since primary ovarian tumours contain type II EBS
Quantitative assessment of emphysematous parenchyma using multidetector-row computed tomography in patients scheduled for endobronchial treatment with one-way valves.
Whole-exome analysis in osteosarcoma to identify a personalized therapy
Osteosarcoma is the most common pediatric primary non-hematopoietic bone
tumor. Survival of these young patients is related to the response to chemotherapy and
development of metastases. Despite many advances in cancer research, chemotherapy
regimens for osteosarcoma are still based on non-selective cytotoxic drugs. It is essential
to investigate new specific molecular therapies for osteosarcoma to increase the survival
rate of these patients. We performed exomic sequence analyses of 8 diagnostic biopsies
of patients with conventional high grade osteosarcoma to advance our understanding
of their genetic underpinnings and to correlate the genetic alteration with the clinical
and pathological features of each patient to identify a personalized therapy.
We identified 18,275 somatic variations in 8,247 genes and we found three
mutated genes in 7/8 (87%) samples (KIF1B, NEB and KMT2C). KMT2C showed the
highest number of variations; it is an important component of a histone H3 lysine 4
methyltransferase complex and it is one of the histone modifiers previously implicated
in carcinogenesis, never studied in osteosarcoma. Moreover, we found a group of 15
genes that showed variations only in patients that did not respond to therapy and
developed metastasis and some of these genes are involved in carcinogenesis and
tumor progression in other tumors.
These data could offer the opportunity to get a key molecular target to identify
possible new strategies for early diagnosis and new therapeutic approaches for
osteosarcoma and to provide a tailored treatment for each patient based on their
genetic profile
Stability of Ge-related point defects and complexes in Ge-doped SiO_2
We analyze Ge-related defects in Ge-doped SiO_2 using first-principles
density functional techniques. Ge is incorporated at the level of ~ 1 mol % and
above. The growth conditions of Ge:SiO_2 naturally set up oxygen deficiency,
with vacancy concentration increasing by a factor 10^5 over undoped SiO_2, and
O vacancies binding strongly to Ge impurities. All the centers considered
exhibit potentially EPR-active states, candidates for the identification of the
Ge(n) centers. Substitutional Ge produces an apparent gap shrinking via its
extrinsic levels.Comment: RevTeX 4 pages, 2 ps figure
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