450 research outputs found
Synthesis of MCM-41 nanomaterial from Algerian bentonite: influence of synthesis pH
Mesoporous materials of the MCM-41 type were synthesized from Algerian bentonite as an aluminosilicate source without the addition of pure silica and aluminum reagents. The samples were synthesized under hydrothermal condition using cetyltrimithylammonium bromide (CTAB) as surfactant. The influence of initial synthesis pH on the material properties of as-synthesis MCM-41 samples was studied at different temperatures of crystallization. The samples were characterized using several techniques e.g. X-ray diffraction (XRD), N2 adsorption-desorption and transmission electron microscope (TEM). The experimental results showed that bentonite can be used as an aluminosilicate source for the synthesis of Al-MCM-41. By decreasing the synthesis temperature of crystallization, it is necessary to decrease the synthesis pH value to form the best ordered hexagonal phase and eliminate the lamellar phase.Keywords: bentonite; alkaline fusion; pH; Al-MCM-4
Anomalous density dependence of static friction in sand
We measured experimentally the static friction force on the surface of
a glass rod immersed in dry sand. We observed that is extremely sensitive
to the closeness of packing of grains. A linear increase of the grain-density
yields to an exponentially increasing friction force. We also report on a novel
periodicity of during gradual pulling out of the rod. Our observations
demonstrate the central role of grain bridges and arches in the macroscopic
properties of granular packings.Comment: plain tex, 6 pages, to appear in Phys.Rev.
Domination spaces and factorization of linear and multilinear summing operators
[EN] It is well known that not every summability property for multilinear operators leads to a factorization theorem. In this paper we undertake a detailed study of factorization schemes for summing linear and nonlinear operators. Our aim is to integrate under the same theory a wide family of classes of mappings for which a Pietsch type factorization theorem holds. Our construction includes the cases of absolutely p-summing linear operators, (p, sigma)-absolutely continuous linear operators, factorable strongly p-summing multilinear operators, (p(1), ... , p(n))-dominated multilinear operators and dominated (p(1), ... , p(n); sigma)-continuous multilinear operators.Supported by the Ministerio de Economia y Competitividad (Spain) under Grant MTM2015-66823-C2-2. Supported by the Ministerio de Economia y Competitividad (Spain) under Grant MTM2012-36740-C02-02.Achour, D.; Dahia, E.; Rueda, P.; Sánchez Pérez, EA. (2016). Domination spaces and factorization of linear and multilinear summing operators. Quaestiones Mathematicae. 39(8):1071-1092. https://doi.org/10.2989/16073606.2016.1253627S1071109239
Intelligent Detection of MAC Spoofing Attack in 802.11 Network
In 802.11, all devices are uniquely identified by a Media
Access Control (MAC) address. However, legitimate MAC
addresses can be easily spoofed to launch various forms of
attacks, such as Denial of Service attacks. Impersonating
the MAC address of a legitimate user poses a big challenge
for cyber crime investigators. Indeed, MAC spoofing makes
the task of identifying the source of the attack very diffi-
cult. Sequence number analysis is a common technique used
to detect MAC spoofing attack. Existing solutions relying
on sequence number analysis, adopt a threshold-based approach
where the gap between consecutive sequence numbers
is compared to a threshold to decide the presence of
a MAC spoofing attack. Nevertheless, threshold-based approach
may lead to a high rate of false alerts due to lost or
duplicated frames.
To overcome the limitations of threshold-based approach,
this paper proposes a detection method that relies on a machine
learning approach, namely Artificial Neural Network
(ANN). ANNs provide the potential to identify and classify
network behavior from limited, noisy, incomplete and nonlinear
data sources. The experimentation results showed
the effectiveness of the proposed detection technique. Moreover,
we proposed a user-friendly graphical representation
of information to support the interpretation of quantitative
results
Prospective assessment of CYP2D6 by genotyping, phenotyping and measurement of tamoxifen, PD 05-09 4-hydroxy-tamoxifen and endoxifen in breast cancer patients treated with tamoxifen.
Tamoxifen (tam) is a widely used endocrine therapy in the treatment of early and advanced stage breast cancer in women and men. It is a pro-drug having weak affinity with the estrogen receptor and needs to be converted to its main metabolite, endoxifen (endox), to have full anticancer activity.
Cytochrome 2D6 (CYP2D6) plays a major role in the metabolism of tamoxifen to endoxifen. It is genetically highly polymorphic and its activity influences profoundly the synthesis of endoxifen and potentially the efficacy of tamoxifen treatment.
Genotyping is currently the most widely used approach in studies and also in clinical practice to categorize patients as poor- (PM), intermediate- (IM), extensive- (EM) and ultra rapid-metabolizers (UM). Some clinicians already use genotyping in order to tailor the endocrine therapy of their patients.
Owing to the large inter-individual variations in concentrations of the active moitey due to genetic and non-genetic influences renders the predictive value of the test uncertain for an individual patient. A significant number of patients classified as EM or IM by genotyping have indeed relatively low endoxifen levels similar to PMs1. This suggests that genotyping is probably not the opti ma l meth o d f or predi cti ng end oxif en l evels
Combined use of zoledronic acid and 153Sm-EDTMP in hormone-refractory prostate cancer patients with bone metastases
Purpose: 153Sm-ethylenediaminetetramethylenephosphonic
acid (EDTMP; Quadramet®) is indicated for the treatment of
painful bone metastases, whereas zoledronic acid (Zometa®)
is indicated for the prevention of skeletal complications.
Because of the different therapeutic effects, combining the
treatments may be beneficial. Both, however, accumulate in
areas with increased osteoblastic activity. Possible drug
interactions were investigated.
Methods: Patients with hormone-refractory prostate cancer
were treated with 18.5 MBq/kg 153Sm-EDTMP in weeks 1
and 3 and with 37 MBq/kg in week 15. Treatment with 4 mg
zoledronic acid began in week 3 and continued every
4 weeks through week 23. In weeks 3 and 15, zoledronic
acid was administered 2 days before 153Sm-EDTMP
treatment. Urine was collected 48 h after injection of
153Sm-EDTMP, and whole-body images were obtained 6,
24 and 48 h post-injection. The effect of zoledronic acid on
total bone uptake of 153Sm-EDTMP was measured indirectly
by the cumulative activity excreted in the urine in weeks 1, 3
and 15. Biodistribution, safety, tolerability and effect on
prostate-specific antigen level were also studied.
Results: The urinary excretion in week 3 divided by the
urinary excretion in week 1 (baseline) times 100% was
mean 98.4±11.6% (median 96.2%). From week 1 to 15,
after four zoledronic acid treatments, the mean ratio was
101.9±10.7% (median 101.8%). Bioequivalence could be
concluded by using a two-sample t test for both perprotocol
(n=13) and full-analysis sets (n=18). Toxicity was
comparable to of monotherapy with 153Sm-EDTMP.
Conclusion: Zoledronic acid treatment does not influence
153Sm-EDTMP skeletal uptake. Combined treatment is
feasible and safe
Sonic hedgehog expression in zebrafish forebrain identifies the teleostean pallidal signaling center and shows preglomerular complex and posterior tubercular dopamine cells to arise from shh cells
Ventralization, a major patterning process in the developing vertebrate neural tube (central nervous system, CNS), depends on Sonic hedgehog (SHH) as a main signaling morphogen. We studied the CNS of late larval and young adult zebrafish in a transgenic shh‐GFP line revealing increased neuroanatomical detail due to the progressed differentiation state compared to earlier stages. Some major findings emerge from the present study. (a) shh –GFP is still expressed along the adult zebrafish CNS neuraxis in most locations seen in larvae. (b) We newly identify a ventroposterior shh pallidal domain representing the basal telencephalic signaling center important for basal ganglia development known in other vertebrates (i.e., the anterior entopeduncular area—basal medial ganglionic eminence of mammals). (c) We further show late‐emerging shh‐GFP positive radial glia cells in the medial zone of the dorsal telencephalon (i.e., the teleostan pallial amygdala). (d) Immunostains for tyrosine hydroxylase demonstrate that there is selective colocalization in adult dopamine cells with shh‐GFP in the posterior tuberculum, including in projection cells to striatum, which represents a striking parallel to amniote mesodiencephalic dopamine cell origin from shh expressing floor plate cells. (e) There is no colocalization of shh and islet1 as shown by respective shh‐GFP and islet1‐GFP lines. (f) The only radially far migrated shh‐GFP cells are located in the preglomerular area. (g) There are no adult cerebellar and tectal shh‐GFP cells confirming their exclusive role during early development as previously reported by our laboratory
Hedgehog-interacting protein is highly expressed in endothelial cells but down-regulated during angiogenesis and in several human tumors
BACKGROUND: The Hedgehog (Hh) signaling pathway regulates a variety of developmental processes, including vasculogenesis, and can also induce the expression of pro-angiogenic factors in fibroblasts postnatally. Misregulation of the Hh pathway has been implicated in a variety of different types of cancer, including pancreatic and small-cell lung cancer. Recently a putative antagonist of the pathway, Hedgehog-interacting protein (HIP), was identified as a Hh binding protein that is also a target of Hh signaling. We sought to clarify possible roles for HIP in angiogenesis and cancer. METHODS: Inhibition of Hh signaling by HIP was assayed by measuring the induction of Ptc-1 mRNA in TM3 cells treated with conditioned medium containing Sonic hedgehog (Shh). Angiogenesis was assayed in vitro by EC tube formation on Matrigel. Expression of HIP mRNA was assayed in cells and tissues by Q-RT-PCR and Western blot. HIP expression in human tumors or mouse xenograft tumors compared to normal tissues was assayed by Q-RT-PCR or hybridization of RNA probes to a cancer profiling array. RESULTS: We show that Hedgehog-interacting protein (HIP) is abundantly expressed in vascular endothelial cells (EC) but at low or undetectable levels in other cell types. Expression of HIP in mouse epithelial cells attenuated their response to Shh, demonstrating that HIP can antagonize Hh signaling when expressed in the responding cell, and supporting the hypothesis that HIP blocks Hh signaling in EC. HIP expression was significantly reduced in tissues undergoing angiogenesis, including PC3 human prostate cancer and A549 human lung cancer xenograft tumors, as well as in EC undergoing tube formation on Matrigel. HIP expression was also decreased in several human tumors of the liver, lung, stomach, colon and rectum when compared to the corresponding normal tissue. CONCLUSION: These results suggest that reduced expression of HIP, a naturally occurring Hh pathway antagonist, in tumor neo-vasculature may contribute to increased Hh signaling within the tumor and possibly promote angiogenesis
Improved coherence of ultrafast spin-transfer-driven precessional switching with synthetic antiferromagnet perpendicular polarizer
International audienceThe coherence of the precessional switching was compared in planar spin-valves comprising either an additional simple perpendicular polarizer or a synthetic antiferromagnet perpendicular polarizer. A significant improvement in the precession coherence was observed experimentally in the second type of samples. Micromagnetic simulations were performed to study the effect of the stray field from the perpendicular polarizer. They provide an explanation for the gradual loss of coherence of the precession in terms of vortex formation, which occurs much faster when a simple perpendicular polarizer is used
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