437 research outputs found
Ceramic production and raw materials in the Tuscan-Ligurian region: an archaeological and petrographic approach in a diachronic perspective
This contribute focuses on the history of ceramic production of a large geographic area from the
archaeological point of view encompassing Liguria and N-W Tuscany and using a petro-archaeometrical approach ( essentially based on thin-section analyses of more than a thousand of samples)
Isselite, Cu6(SO4)(OH)10(H2O)4·h2O, a new mineral species from Eastern Liguria, Italy
The new mineral isselite, Cu6(SO4)(OH)10(H2O)4·H2O, has been discovered in the Lagoscuro mine, Monte Ramazzo mining complex, Genoa, Eastern Liguria, Italy. It occurs as sprays of blue acicular crystals, up to 0.1 mm long, associated with brochantite and posnjakite. Streak is light blue and the lustre is vitreous. Isselite is brittle, with irregular fracture and good cleavage on {001} and {100}. Measured density is 3.00(2) g/cm3. Isselite is optically biaxial (-), with α = 1.599(2), β = 1.633(2) and γ = 1.647(2) (determined in white light). The measured 2V is 63.6(5)°. Dispersion is moderate, with r > v. The optical orientation is X = b, Y = c and Z = a. Isselite is pleochroic, with X = light blue, Y = blue, Z = blue; X << Z < Y. Electron microprobe analyses give (wt.%): SO3 11.45(21), MgO 0.31(7), CoO 1.07(14), NiO 9.41(90), CuO 51.29(126), ZnO 1.10(20), H2Ocalc 24.21, total 98.84. The empirical formula of isselite, based on Σ(Mg,Co,Ni,Cu,Zn) = 6 atoms per formula unit, is (Cu4.80Ni0.94Co0.11Zn0.10Mg0.06)Σ6.00(S1.06O4.19)(OH)10·5H2O. Isselite is orthorhombic, space group Pmn21, with unit-cell parameters a = 6.8070(14), b = 5.8970(12), c = 20.653(4) Å, V = 829.0(3) Å3 and Z = 2. The crystal structure of isselite was refined from single-crystal X-ray diffraction data to R1 = 0.067 on the basis of 2964 reflections with Fo > 4σ(Fo). It shows a layered structure formed by zig-zag {001} layers of Cu-centred polyhedra. Sulfate groups occur in the interlayer along with one H2O group. Isselite is chemically related to redgillite and montetrisaite
Noves dades sobre la producció de cerà mica medieval de Barcelona. La caracterització arqueomètrica del taller del Carrer de Carders
Arran de la troballa d'un taller cerà mic al carrer de Carders de Barcelona, datat entre els segles XII i XIII, s'ha dut a terme la caracterització arqueomètrica de 31 individus per tal de definir les caracterÃstiques quÃmiques i petrogrà fiques de la seva producció. A més, s'han contrastat els resultats amb els obtinguts per a l'altre taller del segle XIII conegut a la ciutat, el del carrer de l'Hospital. L'estudi ha permès de definir el grup de referència (GR) del carrer de Carders, com també indicar l'existència d"individus procedents d'aquesta excavació però que es relacionen amb la producció del carrer de l'Hospital. I a la inversa, l'existència d'individus procedents del carrer de l'Hospital que es relacionen amb el carrer de Carders. Finalment, entre els materials procedents del carrer de Carders s'han identificat dues noves produccions no conegudes anteriorment
Non-Gaussian bubbles in the sky
We point out a possible generation mechanism of non-Gaussian bubbles in the
sky due to bubble nucleation in the early universe. We consider a curvaton
scenario for inflation and assume that the curvaton field phi, whose energy
density is subdominant during inflation but which is responsible for the
curvature perturbation of the universe, is coupled to another field sigma which
undergoes false vacuum decay through quantum tunneling. For this model, we
compute the skewness of the curvaton fluctuations due to its interaction with
sigma during tunneling, that is, on the background of an instanton solution
that describes false vacuum decay. We find that the resulting skewness of the
curvaton can become large in the spacetime region inside the bubble. We then
compute the corresponding skewness in the statistical distribution of the
cosmic microwave background (CMB) temperature fluctuations. We find a
non-vanishing skewness in a bubble-shaped region in the sky. It can be large
enough to be detected in the near future, and if detected it will bring us
invaluable information about the physics in the early universe.Comment: 6 pages, 6 figure
An Antibiotic Protocol To Minimize Emergence Of Drug-Resistant Tuberculosis
The final publication is available at Elsevier via http://dx.doi.org/10.1016/j.physa.2013.12.039 © 2014. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/A within-host model of the spread of tuberculosis is proposed here where the emergence of drug resistance and bacterial dormancy are simultaneously combined. We consider both sensitive and resistant strains of tuberculosis pathogens as well as a dormant state of these bacteria. The dynamics of the within-host system is modeled by a set of coupled differential equations which are numerically solved to find a relation between the within-host bacterial populations and the host health states. The values of the parameters were taken from the current literature when available; a sensitivity analysis was performed for the others. Antibiotic treatment for standard, intermittent and oscillating intermittent protocols is analyzed for different conditions. Our results suggest that the oscillating protocol is the most effective one, that would imply a lower treatment cost.Natural Sciences and Engineering Research Council of Canada (NSERC)Canadian Institutes of Health Research (CIHR)Brazilian agency CNPq [305738/2010-0, 127151/2012-5]FAPERJCAPE
Assessment of non-invasive ICP during CSF infusion test: an approach with transcranial Doppler.
BACKGROUND: This study aimed to compare four non-invasive intracranial pressure (nICP) methods in a prospective cohort of hydrocephalus patients whose cerebrospinal fluid dynamics was investigated using infusion tests involving controllable test-rise of ICP. METHOD: Cerebral blood flow velocity (FV), ICP and non-invasive arterial blood pressure (ABP) were recorded in 53 patients diagnosed for hydrocephalus. Non-invasive ICP methods were based on: (1) interaction between FV and ABP using black-box model (nICP_BB); (2) diastolic FV (nICP_FVd); (3) critical closing pressure (nICP_CrCP); (4) transcranial Doppler-derived pulsatility index (nICP_PI). Correlation between rise in ICP (∆ICP) and ∆nICP and averaged correlations for changes in time between ICP and nICP during infusion test were investigated. RESULTS: From baseline to plateau, all nICP estimators increased significantly. Correlations between ∆ICP and ∆nICP were better represented by nICP_PI and nICP_BB: 0.45 and 0.30 (p < 0.05). nICP_FVd and nICP_CrCP presented non-significant correlations: -0.17 (p = 0.21), 0.21 (p = 0.13). For changes in ICP during individual infusion test nICP_PI, nICP_BB and nICP_FVd presented similar correlations with ICP: 0.39 ± 0.40, 0.39 ± 0.43 and 0.35 ± 0.41 respectively. However, nICP_CrCP presented a weaker correlation (R = 0.29 ± 0.24). CONCLUSIONS: Out of the four methods, nICP_PI was the one with best performance for predicting changes in ∆ICP during infusion test, followed by nICP_BB. Unreliable correlations were shown by nICP_FVd and nICP_CrCP. Changes of ICP observed during the test were expressed by nICP values with only moderate correlations.DC is supported by a Cambridge Commonwealth, European & International Trust Scholarship, University of Cambridge. JD is supported by a Woolf Fisher Trust Scholarship. XL is supported by a Gates Cambridge Trust Scholarship. BCTC is supported by CNPQ (Research Project 203792/2014-9). DC and MC are partially supported by NIHR Brain Injury Healthcare Technology Co-operative, Cambridge, UK.This is the final version of the article. It was first available from Springer via http://dx.doi.org/10.1007/s00701-015-2661-
Non-invasive Monitoring of Intracranial Pressure Using Transcranial Doppler Ultrasonography: Is It Possible?
Although intracranial pressure (ICP) is essential to guide management of patients suffering from acute brain diseases, this signal is often neglected outside the neurocritical care environment. This is mainly attributed to the intrinsic risks of the available invasive techniques, which have prevented ICP monitoring in many conditions affecting the intracranial homeostasis, from mild traumatic brain injury to liver encephalopathy. In such scenario, methods for non-invasive monitoring of ICP (nICP) could improve clinical management of these conditions. A review of the literature was performed on PUBMED using the search keywords 'Transcranial Doppler non-invasive intracranial pressure.' Transcranial Doppler (TCD) is a technique primarily aimed at assessing the cerebrovascular dynamics through the cerebral blood flow velocity (FV). Its applicability for nICP assessment emerged from observation that some TCD-derived parameters change during increase of ICP, such as the shape of FV pulse waveform or pulsatility index. Methods were grouped as: based on TCD pulsatility index; aimed at non-invasive estimation of cerebral perfusion pressure and model-based methods. Published studies present with different accuracies, with prediction abilities (AUCs) for detection of ICP ≥20 mmHg ranging from 0.62 to 0.92. This discrepancy could result from inconsistent assessment measures and application in different conditions, from traumatic brain injury to hydrocephalus and stroke. Most of the reports stress a potential advantage of TCD as it provides the possibility to monitor changes of ICP in time. Overall accuracy for TCD-based methods ranges around ±12 mmHg, with a great potential of tracing dynamical changes of ICP in time, particularly those of vasogenic nature.Cambridge Commonwealth, European & International Trust Scholarship (University of Cambridge) provided financial support in the form of Scholarship funding for DC. Woolf Fisher Trust provided financial support in the form of Scholarship funding for JD. Gates Cambridge Trust provided financial support in the form of Scholarship funding for XL. CNPQ provided financial support in the form of Scholarship funding for BCTC (Research Project 203792/2014-9). NIHR Brain Injury Healthcare Technology Co-operative, Cambridge, UK provided financial support in the form of equipment funding for DC, BC and MC. The sponsors had no role in the design or conduct of this manuscript.This is the final version of the article. It first appeared from Springer via http://dx.doi.org/10.1007/s12028-016-0258-
Orthotopic induction of CH157MN convexity and skull base meningiomas into nude mice using stereotactic surgery and MRI characterization.
High Order Correction Terms for The Peak-Peak Correlation Function in Nearly-Gaussian Models
One possible way to investigate the nature of the primordial power spectrum
fluctuations is by investigating the statistical properties of the local
maximum in the density fluctuation fields. In this work we present a study of
the mean correlation function, , and the correlation function for high
amplitude fluctuations (the peak-peak correlation) in a slighlty non-Gaussian
context. From the definition of the correlation excess, we compute the Gaussian
two-point correlation function and, using an expansion in Generalized Hermite
polynomials, we estimate the correlation of high density peaks in a
non-Gaussian field with generic distribution and power spectrum. We also apply
the results obtained to a scale-mixed distribution model, which correspond to a
nearly Gaussian model. The results reveal that, even for a small deviation from
Gaussianity, we can expect high density peaks to be much more correlated than
in a Gaussian field with the same power spectrum. In addition, the calculations
reveal how the amplitude of the peaks in the fluctuations field is related to
the existing correlations. Our results may be used as an additional tool to
investigate the behavior of the N-point correlation function, to understand how
non-Gaussian correlations affect the peak-peak statistics and extract more
information about the statistics of the density field.Comment: Accepted for publication in A&
Foreground influence on primordial non-Gaussianity estimates: needlet analysis of WMAP 5-year data
We constrain the amplitude of primordial non-Gaussianity in the CMB data
taking into account the presence of foreground residuals in the maps. We
generalise the needlet bispectrum estimator marginalizing over the amplitudes
of thermal dust, free-free and synchrotron templates. We apply our procedure to
WMAP 5 year data, finding fNL= 38\pm 47 (1 \sigma), while the analysis without
marginalization provides fNL= 35\pm 42. Splitting the marginalization over each
foreground separately, we found that the estimates of fNL are positively cross
correlated of 17%, 12% with the dust and synchrotron respectively, while a
negative cross correlation of about -10% is found for the free-free component.Comment: Submitted to MNRA
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