1,552 research outputs found
Primes and prime ideals in short intervals
We prove the analog of Cram\'er's short intervals theorem for primes in
arithmetic progressions and prime ideals, under the relevant Riemann
Hypothesis. Both results are uniform in the data of the underlying structure.
Our approach is based mainly on the inertia property of the counting functions
of primes and prime ideals.Comment: minor change to Proposition
Backscattering Differential Ghost Imaging in Turbid Media
In this Letter we present experimental results concerning the retrieval of
images of absorbing objects immersed in turbid media via differential ghost
imaging (DGI) in a backscattering configuration. The method has been applied,
for the first time to our knowledge, to the imaging of small thin black objects
located at different depths inside a turbid solution of polystyrene nanospheres
and its performances assessed via comparison with standard imaging techniques.
A simple theoretical model capable of describing the basic optics of DGI in
turbid media is proposed.Comment: 5 pages, 6 figure
Explicit bounds for generators of the class group
Assuming Generalized Riemann's Hypothesis, Bach proved that the class group SICK of a number field K may be generated using prime ideals whose norm is bounded by 121og(2)delta(K), and by (4 + o(l)) log(2) delta(K) asymptotically, where delta(K) is the absolute value of the discriminant of K. Under the same assumption, Belabas, Diaz y Diaz and Friedman showed a way to determine a set of prime ideals that generates SICK and which performs better than Bach's bound in computations, but which is asymptotically worse. In this paper we show that SICK is generated by prime ideals whose norm is bounded by the minimum of 4.01 log(2) delta(K), 4(l + (2 pi e(gamma))N-_(K))(2) log(2) delta(k) and 4( log delta(k) + log log delta(K) - (gamma + log 2 pi)N-K + 1 + (N-K + 1) log(7log delta(K)/log delta(K))(2). Moreover, we prove explicit upper bounds for the size of the set determined by Belabas, Diaz y Diaz and Friedma's algorithms, confirming that it has size SIC (log delta(K) log log delta(K))(2). In addition, we propose a different algorithm which produces a set of generators which satisfies the above mentioned bounds and in explicit computations turns out to be smaller than log(2) delta(K) except for 7 out of the 31292 fields we tested
Nucleosynthesis in Advective Accretion Disks Around Galactic and Extra-Galactic Black Holes
We compute the nucleosynthesis of materials inside advective disks around
black holes. We show that composition of incoming matter can change
significantly depending on the accretion rate and accretion disks. These works
are improvements on the earlier works in thick accretion disks of Chakrabarti,
Jin & Arnett (1987) in presence of advection in the flow.Comment: Latex pages including figures. Kluwer Style files included. Appearing
in `Observational Evidence for Black Holes in the Universe', ed. Sandip K.
Chakrabarti, Kluwer Academic Publishers (DORDRECHT: Holland
Explicit short intervals for primes in arithmetic progressions on GRH
We prove explicit versions of Cram\ue9r's theorem for primes in arithmetic progressions, on the assumption of the generalised Riemann hypothesis
Trans-nasal endoscopic and intra-oral combined approach for odontogenic cysts
Maxillary cysts are a common finding in maxillofacial surgery, dentistry and otolaryngology. Treatment is surgical; a traditional approach includes Caldwell-Luc and other intra-oral approaches. In this article, we analyse the outcomes of 9 patients operated on using a combined intra-oral and trans-nasal approach to the aforementioned disease. Although the number of patients is small, the good results of this study suggest that the combined approach might be a reliable treatment option
Étude cytogénétique sur certaines races bovines italiennes en voie de diminution ou menacées de disparition
International audienc
SHORT COMMUNICATION: Urban malaria in Dodoma and Iringa, Tanzania
Cross sectional malaria parasitaemia and entomological surveys were carried out in urban Iringa and Dodoma in Tanzania. A total of 395 and 392 schoolchildren (age range= 6-15 years) were screened for malaria parasites in Iringa and Dodoma, respectively. Plasmodium falciparum was the predominant malaria parasite (Iringa= 100%, Dodoma= 97.8%). Malaria parasitaemia was observed in 14.9% and 12% of the schoolchildren in Iringa and Dodoma, respectively. The geometric mean parasite density for P. falciparum was higher (632 parasites/μl) in Iringa than in Dodoma (74.1 parasites/μl). The average spleen rates were 0.5% and 2% in Iringa and Dodoma, respectively. A slightly higher haemoglobin level was observed among schoolchildren in Dodoma (10.2g/dl) than in Iringa (9.5g/dl). Only a few Anopheles gambiae sensu lato were collected indoors in the two areas. On the average 47.3% and 80% of the children in Iringa and Dodoma, respectively were sleeping under mosquito nets. Although malaria endemicity in the two municipalities is low, unplanned rapid urbanisation is likely to change malaria epidemiology in Tanzania. Continuous malaria and mosquito density surveillance should therefore, form an in integral part of the malaria control strategies in urban areas. Communities should be continuously sensitised to use insecticide-treated mosquito nets and strengthen community-based environmental management to minimise malaria breeding sites. Keywords: urban, malaria, schoolchildren, Tanzania Tanzania Health Research Bulletin Vol. 8 (2) 2006: pp. 115-11
Dihydrotanshinone I exhibits antitumor effects via β-catenin downregulation in papillary thyroid cancer cell lines
Thyroid cancer is the most common endocrine carcinoma and, among its different subtypes, the papillary subtype (PTC) is the most frequent. Generally, PTCs are well differentiated, but a minor percentage of PTCs are characterized by a worse prognosis and more aggressive behavior. Phytochemicals, naturally found in plant products, represent a heterogeneous group of bioactive compounds that can interfere with cell proliferation and the regulation of the cell cycle, taking part in multiple signaling pathways that are often disrupted in tumor initiation, proliferation, and progression. In this work, we focused on 15,16-dihydrotanshinone I (DHT), a tanshinone isolated from Salvia miltiorrhiza Bunge (Danshen). We first evaluated DHT biological effect on PTC cells regarding cell viability, colony formation ability, and migration capacity. All of these parameters were downregulated by DHT treatment. We then investigated gene expression changes after DHT treatment by performing RNA-seq. The analysis revealed that DHT significantly reduced the Wnt signaling pathway, which plays a role in various diseases, including cancer. Finally, we demonstrate that DHT treatment decreases protein levels of β-catenin, a final effector of canonical Wnt signaling pathway. Overall, our data suggest a possible use of this nutraceutical as an adjuvant in the treatment of aggressive papillary thyroid carcinoma
GSK2801 Reverses Paclitaxel Resistance in Anaplastic Thyroid Cancer Cell Lines through MYCN Downregulation
Anaplastic thyroid cancer (ATC) is a very rare, but extremely aggressive form of thyroid malignancy, responsible for the highest mortality rate registered for thyroid cancer. Treatment with taxanes (such as paclitaxel) is an important approach in counteracting ATC or slowing its progression in tumors without known genetic aberrations or those which are unresponsive to other treatments. Unfortunately, resistance often develops and, for this reason, new therapies that overcome taxane resistance are needed. In this study, effects of inhibition of several bromodomain proteins in paclitaxel-resistant ATC cell lines were investigated. GSK2801, a specific inhibitor of BAZ2A, BAZ2B and BRD9, was effective in resensitizing cells to paclitaxel. In fact, when used in combination with paclitaxel, it was able to reduce cell viability, block the ability to form colonies in an anchor-independent manner, and strongly decrease cell motility. After RNA-seq following treatment with GSK2801, we focused our attention on MYCN. Based on the hypothesis that MYCN was a major downstream player in the biological effects of GSK2801, we tested a specific inhibitor, VPC-70619, which showed effective biological effects when used in association with paclitaxel. This suggests that the functional deficiency of MYCN determines a partial resensitization of the cells examined and, ultimately, that a substantial part of the effect of GSK2801 results from inhibition of MYCN expression
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