4,876 research outputs found
Exploiting non-constant safe memory in resilient algorithms and data structures
We extend the Faulty RAM model by Finocchi and Italiano (2008) by adding a
safe memory of arbitrary size , and we then derive tradeoffs between the
performance of resilient algorithmic techniques and the size of the safe
memory. Let and denote, respectively, the maximum amount of
faults which can happen during the execution of an algorithm and the actual
number of occurred faults, with . We propose a resilient
algorithm for sorting entries which requires time and uses safe memory words. Our
algorithm outperforms previous resilient sorting algorithms which do not
exploit the available safe memory and require time. Finally, we exploit our sorting algorithm for
deriving a resilient priority queue. Our implementation uses safe
memory words and faulty memory words for storing keys, and
requires amortized time for each insert and
deletemin operation. Our resilient priority queue improves the amortized time required by the state of the art.Comment: To appear in Theoretical Computer Science, 201
Real time vibronic coupling dynamics in organic conjugated systems
In this work we show the potentialities of applying impulsive coherent vibrational spectroscopy to conjugated systems relevant for applications. We studied films of sexithiophene, a candidate for large area molecular electronics, poly-phenylene vinylene, a prototype electroluminescent material, and polydiacetylene, very promising for applications in photonic devices. These experiments demonstrate the possibility of studying coherent molecular dynamics in organic systems with extremely high time resolution
PREDICTIONS ON THE SEISMIC RESPONSE OF MONUMENTAL TOWERS ON SOFT SOIL
After the damages to the cultural heritage caused by the most recent earthquakes, the protection of ancient buildings is an urgent and relevant theme in Europe, especially in the Mediterranean countries, characterized by high seismic hazard. The fine tuning of the seismic protection requires analyses on refined models in order to catch the dynamic behaviour of the soilâfoundationâ structure system in a lifelike way. Neglecting soil structure interaction effects, in fact, may be conservative or not, depending on the structural pattern and the nature of the subsoil. Focusing on the historical towers, the most symbolic building among monuments, a method is here proposed for preliminary predictions on the variation of natural period and damping ratio due to the dynamic interaction between soil and structure. The simplified approach is then applied to three cases of monumental towers on soft soil, located in three European cities, characterized by high seismic hazard
Charge carrier generation in a conjugated polymer studied via ultrafast pump-push-probe experiments
Conjugated polymers find rapidly growing application in electroluminescent displays and are extensively studied for use in photovoltaics and laser diodes. For a wide range of conjugated materials ultrafast pump-probe experiments have revealed the excited state dynamics of singlet and triplet excitons as well as positively and negatively charged polarons. Charge carriers play a key role in all the above mentioned applications. However, there is yet no clear picture of the mechanisms which lead to their generation. Photocurrent excitation cross-correlation measurement on methyl-substituted ladder-type poly(para)phenyl (m-LPPP), a prototypical conjugated polymer with very appealing properties for the above mentioned applications, have suggested that charge carrier generation occurs preferentially from higher lying states during energy migration. Our approach to examining this mechanism consists of an innovative modification of the ultrafast time-resolved pump-probe technique
A 22-Week-Old Fetus with Nager Syndrome and Congenital Diaphragmatic Hernia due to a Novel SF3B4 Mutation.
Nager syndrome, or acrofacial dysostosis type 1 (AFD1), is a rare multiple malformation syndrome characterized by hypoplasia of first and second branchial arches derivatives and appendicular anomalies with variable involvement of the radial/axial ray. In 2012, AFD1 has been associated with dominant mutations in SF3B4. We report a 22-week-old fetus with AFD1 associated with diaphragmatic hernia due to a previously unreported SF3B4 mutation (c.35-2A>G). Defective diaphragmatic development is a rare manifestation in AFD1 as it is described in only 2 previous cases, with molecular confirmation in 1 of them. Our molecular finding adds a novel pathogenic splicing variant to the SF3B4 mutational spectrum and contributes to defining its prenatal/fetal phenotype
Primary Hyperparathyroidism in Older People: Surgical Treatment with Minimally Invasive Approaches and Outcome
Introduction. Elderly patients with primary hyperparathyroidism (pHPT) are often not referred to surgery because of their associated comorbidities that may increase surgical risk. The aim of the study was to review indications and results of minimally invasive approach parathyroidectomy in elderly patients to evaluate its impact on outcome. Materials and Methods. All patients of 70 years of age or older undergoing minimally approach parathyroidectomy at our Department from May 2005 to May 2011 were reviewed. Data collected included patients demographic information, biochemical pathology, time elapsed from pHPT diagnosis to surgical intervention, operative findings, complications, and results of postoperative biochemical studies. Results and Discussion. 37 patients were analysed. The average length of stay was 2.8 days. 11 patients were discharged within 24 hours after their operation. Morbidity included 6 transient symptomatic postoperative hypocalcemias while one patient developed a transient laryngeal nerve palsy. Time elapsed from pHPT diagnosis to first surgical visit evidences that the elderly patients were referred after their disease had progressed. Conclusions. Our data show that minimally invasive approach to parathyroid surgery seems to be safe and curative also in elderly patients with few associated risks because of combination of modern preoperative imaging, advances in surgical technique, and advances in anesthesia care
The kinesin Eg5 inhibitor K858 induces apoptosis but also survivin-related chemoresistance in breast cancer cells
Inhibitors of kinesin spindle protein Eg5 are characterized by pronounced antitumor activity. Our group has recently synthesized and screened a library of 1,3,4-thiadiazoline analogues with the pharmacophoric structure of K858, an Eg5 inhibitor. We herein report the effects of K858 on four different breast cancer cell lines: MCF7 (luminal A), BT474 (luminal B), SKBR3 (HER2 like) and MDA-MB231 (basal like). We demonstrated that K858 displayed anti-proliferative activity on every analyzed breast cancer cell line by inducing apoptosis. However, at the same time, we showed that K858 up-regulated survivin, an anti-apoptotic molecule. We then performed a negative regulation of survivin expression, with the utilization of wortmannin, an AKT inhibitor, and obtained a significant increase of K858-dependent apoptosis.
These data demonstrate that K858 is a potent inhibitor of replication and induces apoptosis in breast tumor cells, independently from the tumor phenotype. This anti-proliferative response of tumor cells to K858 can be limited by the contemporaneous over-expression of survivin; consequently, the reduction of survivin levels, obtained with AKT inhibitors, can sensitize tumor cells to K858-induced apoptosis
Studying the universality of field induced tunnel ionization times via high-order harmonic spectroscopy
High-harmonics generation spectroscopy is a promising tool for resolving
electron dynamics and structure in atomic and molecular systems. This scheme,
commonly described by the strong field approximation, requires a deep insight
into the basic mechanism that leads to the harmonics generation. Recently, we
have demonstrated the ability to resolve the first stage of the process --
field induced tunnel ionization -- by adding a weak perturbation to the strong
fundamental field. Here we generalize this approach and show that the
assumptions behind the strong field approximation are valid over a wide range
of tunnel ionization conditions. Performing a systematic study -- modifying the
fundamental wavelength, intensity and atomic system -- we observed a good
agreement with quantum path analysis over a range of Keldysh parameters. The
generality of this scheme opens new perspectives in high harmonics
spectroscopy, holding the potential of probing large, complex molecular
systems.Comment: 11 pages, 5 figure
The coherent dynamics of photoexcited green fluorescent proteins
The coherent dynamics of vibronic wave packets in the green fluorescent
protein is reported. At room temperature the non-stationary dynamics following
impulsive photoexcitation displays an oscillating optical transmissivity
pattern with components at 67 fs (497 cm-1) and 59 fs (593 cm-1). Our results
are complemented by ab initio calculations of the vibrational spectrum of the
chromophore. This analysis shows the interplay between the dynamics of the
aminoacidic structure and the electronic excitation in the primary optical
events of green fluorescent proteins.Comment: accepted for publication in Physical Review Letter
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