2,144 research outputs found
A decidable policy language for history-based transaction monitoring
Online trading invariably involves dealings between strangers, so it is
important for one party to be able to judge objectively the trustworthiness of
the other. In such a setting, the decision to trust a user may sensibly be
based on that user's past behaviour. We introduce a specification language
based on linear temporal logic for expressing a policy for categorising the
behaviour patterns of a user depending on its transaction history. We also
present an algorithm for checking whether the transaction history obeys the
stated policy. To be useful in a real setting, such a language should allow one
to express realistic policies which may involve parameter quantification and
quantitative or statistical patterns. We introduce several extensions of linear
temporal logic to cater for such needs: a restricted form of universal and
existential quantification; arbitrary computable functions and relations in the
term language; and a "counting" quantifier for counting how many times a
formula holds in the past. We then show that model checking a transaction
history against a policy, which we call the history-based transaction
monitoring problem, is PSPACE-complete in the size of the policy formula and
the length of the history. The problem becomes decidable in polynomial time
when the policies are fixed. We also consider the problem of transaction
monitoring in the case where not all the parameters of actions are observable.
We formulate two such "partial observability" monitoring problems, and show
their decidability under certain restrictions
Estudio paleoestomatolĂłgico de la poblaciĂłn tardorromana de La Muela (Valencia de Don Juan, LeĂłn)
X Congreso Nacional de PaleopatologĂa. Univesidad AutĂłnoma de Madrid, septiembre de 200
Transcranial Magnetic Resonance Imaging-Guided Focused Ultrasound Treatment at 1.5 T: A Retrospective Study on Treatment- and Patient-Related Parameters Obtained From 52 Procedures
Objective: To present a retrospective analysis of patient- and sonication-related parameters of a group of patients treated with a transcranial magnetic resonance imaging (MRI)-guided focused ultrasound (tcMRgFUS) system integrated with a 1.5-T MRI unit. Methods: The data obtained from 59 patients, who underwent the tcMRgFUS procedure from January 2015 to April 2019, were retrospectively reviewed for this study. The following data, among others, were mainly collected: skull density ratio (SDR), skull area (SA), number of available transducer elements (Tx), and estimated focal power at target (FP). For each of the four different treatment stages, we calculated the number of sonication processes (S-n), user-defined sonication power (S-p), effective measured power (S-mp), sonication duration (S-d), user-defined energy (E), effective measured energy (E-m), maximum temperature (T-max), and MR thermometry plane orientation. Furthermore, the time delay between each sonication (S-t) and the total treatment time (T-t) were recorded. Results: Fifty-two patients (40 males and 12 females; age 64.51 +/- SD 11.90 years; range 26-86 years), who underwent unilateral Vim thalamotomy (left = 50, 96.15%; right = 2, 3.85%) for medication-refractory essential tremor (n = 39; 78%) or Parkinson tremor (n = 13; 22%) were considered. A total of 1,068 (95.10%) sonication processes were included in our final analysis (average S-n per treatment: 20.65 +/- 6.18; range 13-41). The energy released onto the planned target was found to decrease with the SDR for all temperature ranges. A positive correlation was observed between the slope of T-max vs. E-m plot and the SDR (R-2 = 0.765; p < 0.001). In addition, the T-max was positively correlated with SDR (R-2 = 0.398; p < 0.005). On the contrary, no significant correlation was found between SDR and SA or Tx. An analysis of the MR thermometry scanning plane indicated that, at our site, the axial and the coronal planes were used (on average) 10.4 (SD +/- 3.8) and 7.7 (SD +/- 3.0) times, respectively, whereas the sagittal plane was used only 2.5 (SD +/- 3.0) times per treatment. Conclusion: Our results confirm the factors that significantly influence the course of a tcMRgFUS procedure even when a 1.5-T MRI scanner is used for procedure guidance. The experience we gained in this study indicates that the SDR remains one of the most significant technical parameters to be considered in a tcMRgFUS procedure. The possibility of prospectively setting the sonication energy according to the presented curves of energy delivery as a function of SDR for each treatment stage could provide a further understanding and a greater awareness of this emerging technology
Ziziphus lotus (L.) Lam. as a source of health promoting products: metabolomic profile, antioxidant and tyrosinase inhibitory activities
The methanolic extract of the stem bark of a wild species of jujube, Ziziphus lotus (L.) Lam., growing in Sicily, was chemically and biologically investigated. The chemical profile was defined by UHPLC-HR-ESI-Orbitrap/MS analysis whereas antioxidant and tyrosinase inhibitory activities were investigated by in vitro assays. The extract showed a high total phenolic and flavonoid content (TPC = 271.65 GAE/g and TFC = 188.11 RE/g extract). Metabolomic analysis revealed a rich phytocomplex characterized by phenols, cyclopeptide alkaloids, and triterpenoid saponins, some of which here detected for the first time. The mushroom tyrosinase inhibition assay displayed that the methanolic extract efficiently inhibits the monophenolase and diphenolase activity. Furthermore, the extract showed a strong ability to scavenge DPPH, a good Fe3+ reducing antioxidant power, in addition to a Fe2+ chelating activity. Taken together, these results suggest possible novel applications of wild jujube stem bark as a source of potential skin-care agents with several uses in pharmaceutical and cosmetic industries
Measurements of polarized photo-pion production on longitudinally polarized HD and Implications for Convergence of the GDH Integral
We report new measurements of inclusive pion production from frozen-spin HD
for polarized photon beams covering the Delta(1232) resonance. These provide
data simultaneously on both H and D with nearly complete angular distributions
of the spin-difference cross sections entering the Gerasimov-Drell-Hearn (GDH)
sum rule. Recent results from Mainz and Bonn exceed the GDH prediction for the
proton by 22 microbarns, suggesting as yet unmeasured high-energy components.
Our pi0 data reveal a different angular dependence than assumed in Mainz
analyses and integrate to a value that is 18 microbarns lower, suggesting a
more rapid convergence. Our results for deuterium are somewhat lower than
published data, considerably more precise and generally lower than available
calculations.Comment: 4 pages, 4 figures. Submitted for publication in Physical Review
Letter
Internationalisation, cultural distance and country characteristics: a Bayesian analysis of SME's financial performance
Relying on the accounting data of a panel of 403 Italian manufacturing SMEs collected over a period of 5 years, we find results suggesting that multinationality per se does not impact on the economic performance of international small and medium sized firms. It is the characteristics of the country selected i.e. the political hazard, the financial stability and the economic performance that significantly influence SMEs financial performance. The management implication for small and medium sized firms selecting and entering new geographic markets is significant, since our results show that for SMEs it is the market selection process that really matters and not the degree of multinationality
Organic film thickness influence on the bias stress instability in Sexithiophene Field Effect Transistors
In this paper, the dynamics of bias stress phenomenon in Sexithiophene (T6)
Field Effect Transistors (FETs) has been investigated. T6 FETs have been
fabricated by vacuum depositing films with thickness from 10 nm to 130 nm on
Si/SiO2 substrates. After the T6 film structural analysis by X-Ray diffraction
and the FET electrical investigation focused on carrier mobility evaluation,
bias stress instability parameters have been estimated and discussed in the
context of existing models. By increasing the film thickness, a clear
correlation between the stress parameters and the structural properties of the
organic layer has been highlighted. Conversely, the mobility values result
almost thickness independent
Dispersion enhancement and damping by buoyancy driven flows in 2D networks of capillaries
The influence of a small relative density difference on the displacement of
two miscible liquids is studied experimentally in transparent 2D networks of
micro channels. Both stable displacements in which the denser fluid enters at
the bottom of the cell and displaces the lighter one and unstable displacements
in which the lighter fluid is injected at the bottom and displaces the denser
one are realized. Except at the lowest mean flow velocity U, the average
of the relative concentration satisfies a convection-dispersion
equation. The dispersion coefficient is studied as function of the relative
magnitude of fluid velocity and of the velocity of buoyancy driven fluid
motion. A model is suggested and its applicability to previous results obtained
in 3D media is discussed
Food habits, Life style, Genetic background in tumour initiation and progression of Reproductive system
The relationship between diet and health is really engaging, it has been showed that modifications in dietary intake and the benefits of the Mediterranean diet, can importantly increase life expectancy, reducing the risk of chronic disease and improve quality of life. In this way, several studies assigned a highest reduction in tumor incidence to monosaturated and saturated lipids present in vegetables, such olive oil. On these basis, this study will be focused on the comprehension and understanding of initiation and progression phases linked to environmental stressors and food habits in the tumours of the reproductive system (breast and ovarian cancer). Recently it has been described the potential effect of the olive tree (Olea europaea) leaves, oil and fruits to inhibit proliferation and to induce apoptosis in different cancer cell lines. The phenolic fraction of Olive extract becomes specially interesting, including a polyphenol called Oleuropein (OL) present at higher levels in olives and leaves- as well as its hydrolysis metabolite, Hydroxytyrosol (HT). Taking this background into account, we have focused our research in the analysis of Olive leaf extracts with a high content in OL (48%) as a potential cell viability reducing agent on a malignant triple negative breast
cancer cell line, MDA-MB- 231, which is highly aggressive. On this model, cell viability was measured with a MTS assay 24 and 48 h after the treatment with the Olive extract. The preliminary results seem to indicate that this extract at high concentrations (200-400µg/mL) determines a reduction in the MDA- MB-231 cell viability
Gathering Anonymous, Oblivious Robots on a Grid
We consider a swarm of autonomous mobile robots, distributed on a
2-dimensional grid. A basic task for such a swarm is the gathering process: All
robots have to gather at one (not predefined) place. A common local model for
extremely simple robots is the following: The robots do not have a common
compass, only have a constant viewing radius, are autonomous and
indistinguishable, can move at most a constant distance in each step, cannot
communicate, are oblivious and do not have flags or states. The only gathering
algorithm under this robot model, with known runtime bounds, needs
rounds and works in the Euclidean plane. The underlying time
model for the algorithm is the fully synchronous model. On
the other side, in the case of the 2-dimensional grid, the only known gathering
algorithms for the same time and a similar local model additionally require a
constant memory, states and "flags" to communicate these states to neighbors in
viewing range. They gather in time .
In this paper we contribute the (to the best of our knowledge) first
gathering algorithm on the grid that works under the same simple local model as
the above mentioned Euclidean plane strategy, i.e., without memory (oblivious),
"flags" and states. We prove its correctness and an time
bound in the fully synchronous time model. This time bound
matches the time bound of the best known algorithm for the Euclidean plane
mentioned above. We say gathering is done if all robots are located within a
square, because in such configurations cannot be
solved
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