1,697 research outputs found
Modeling Lepton-Nucleon Inelastic Scattering from High to Low Momentum Transfer
We present a model for inclusive charged lepton-nucleon and
(anti)neutrino-nucleon cross sections at momentum transfer squared, ,
. We quantify the impact of existing low-Q charged-lepton
deep-inelastic scattering (DIS) data on effects due to high-twist operators and
on the extraction of parton distribution functions (PDFs). No evidence is found
for twist-6 contributions to structure functions (SF), and for a twist-4 term
in the logitudinal SF at . We find that DIS data are consistent
with the NNLO QCD approximation with the target mass and phenomenological high
twist corrections. For , we extend extrapolation of the
operator product expansion, preserving the low- current-conservation
theorems. The procedure yields a good description of data down to . An updated set of PDFs with reduced uncertainty and applicable
down to small momentum transfers in the lepton-nucleon scattering is obtained.Comment: 10 pages, 6 figures, proceedings of the 5th International Workshop on
Neutrino-Nucleus Interactions in the Few-GeV Region (NuInt07), Batavia,
Illinois, 30 May - 3 Jun 200
APPLICAZIONE DI TECNICHE DI COLLASSAMENTO IPOCENTRALE A DUE SEQUENZE SISMICHE DI BASSA ENERGIA NELL’APPENNINO MERIDIONALE
In this study we analyse two recent low energy (Mdmax = 4.1) seismic sequences (1990-1997) that affected the northern sector (Sannio-Benevento area) of the Southern Apennines chain. We applied the Best Estimate Method to earthquake locations in order to constrain the position and geometry of the seismogenic structures. The most striking features of the obtained fault geometries indicate that earthquakes of the 1990 Benevento sequence align along a NW-SE striking structure, while the earthquakes of the 1997 Sannio sequence outline a NNE-SSW striking structure. The southernmost NW-SE structure dips towards the NE, is characterized by a conjugate fault arrangement and overlies the fault responsible for a larger historical earthquake (Iomax = XI MCS, 1688 earthquake). Available focal mechanisms from earthquakes that occurred on the recognized NW-SE and NE-SW faults are consistent with dip-slip normal solutions. This suggests the occurrence of coexisting NW-SE and NE-SW extension in the Southern Apennines
Focused ultrasound-enabled brain tumor liquid biopsy
Abstract Although blood-based liquid biopsies have emerged as a promising non-invasive method to detect biomarkers in various cancers, limited progress has been made for brain tumors. One major obstacle is the blood-brain barrier (BBB), which hinders efficient passage of tumor biomarkers into the peripheral circulation. The objective of this study was to determine whether FUS in combination with microbubbles can enhance the release of biomarkers from the brain tumor to the blood circulation. Two glioblastoma tumor models (U87 and GL261), developed by intracranial injection of respective enhanced green fluorescent protein (eGFP)-transduced glioblastoma cells, were treated by FUS in the presence of systemically injected microbubbles. Effect of FUS on plasma eGFP mRNA levels was determined using quantitative polymerase chain reaction. eGFP mRNA were only detectable in the FUS-treated U87 mice and undetectable in the untreated U87 mice (maximum cycle number set to 40). This finding was replicated in GL261 mice across three different acoustic pressures. The circulating levels of eGFP mRNA were 1,500–4,800 fold higher in the FUS-treated GL261 mice than that of the untreated mice for the three acoustic pressures. This study demonstrated the feasibility of FUS-enabled brain tumor liquid biopsies in two different murine glioma models across different acoustic pressures
Numerical and structural aberrations in advanced neuroblastoma tumours by CGH analysis; survival correlates with chromosome 17 status
Rapid tumour progression in neuroblastoma is associated with MYCN amplification, deletion of the short arm of chromosome 1 and gain of 17q. However, patients with advanced disease without MYCN amplification and/or 1p deletion have a very poor outcome too, which suggests other genetic defects may predict an unfavourable prognosis. We employed CGH to study 22 tumours of patients at stages 3 and 4 over one year of age (6 and 16 cases respectively). Patients were divided in groups (A) long-term survivors and (B) short-term survivors. CGH showed a total of 226 chromosome imbalances (110 in group A and 116 in group B). The neuroblastoma cells of long-term survivors showed a preponderance of numerical aberrations (54%vs 43%); particularly gains of entire chromosomes 1 (P< 0.03), 7 (P< 0.04) and 19 (P< 0.05). An extra copy of 17 was detected in 6/8 (75%) samples of group A and only 1/14 (7%) samples of group B (P< 0.002). Conversely, tumours of patients who died from disease progression displayed a higher frequency of structural abnormalities (43%vs 35%), including loss of 1p, 9p, 11q, 15q and 18q and gain of 12q, although the difference was not significant (P= 0.24). Unbalanced gain of 17q was detected in 8/14 (57%) tumours of group B and only 1/8 (13%) tumours of group A (P< 0.05). The peculiar genetic difference observed in the tumours of long and short-term survivors may have prognostic relevance. © 2000 Cancer Research Campaig
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Finite element analysis of the Arquin-designed CMU wall under a dynamic (blast) load.
The Arquin Corporation designed a CMU (concrete masonry unit) wall construction and reinforcement technique that includes steel wire and polymer spacers that is intended to facilitate a faster and stronger wall construction. Since the construction method for an Arquin-designed wall is different from current wall construction practices, finite element computer analyses were performed to estimate the ability of the wall to withstand a hypothetical dynamic load, similar to that of a blast from a nearby explosion. The response of the Arquin wall was compared to the response of an idealized standard masonry wall exposed to the same dynamic load. Results from the simulations show that the Arquin wall deformed less than the idealized standard wall under such loading conditions. As part of a different effort, Sandia National Laboratories also looked at the relative static response of the Arquin wall, results that are summarized in a separate SAND Report
Nuclear Effects in Neutrino Structure Functions
We discuss calculation of nuclear corrections to the structure functions for
the deep-inelastic scattering of muon and (anti)neutrino. Our approach includes
a QCD description of the nucleon structure functions as well as the treatment
of Fermi motion and nuclear binding, off-shell correction to bound nucleon
structure functions, nuclear pion excess and nuclear shadowing. We emphasize
the dependence of nuclear effects on the type and C-parity of (anti)neutrino
structure functions. We also examine the interplay between different nuclear
effects in the Adler and the Gross-Llewellyn-Smith sum rules for nuclei.Comment: 8 pages, 2 figures, to appear in the proceedings of 5th International
Workshop on Neutrino-Nucleus Interactions in the Few-GeV Region (NuInt07),
Batavia, Illinois, 30 May - 3 Jun 200
Towards an on-chip platform for the controlled application of forces via magnetic particles: A novel device for mechanobiology
In-vitro tests and analyses are of fundamental importance for investigating biological mechanisms in
cells and bio-molecules. The controlled application of forces to activate specific bio-pathways and
investigate their effects, mimicking the role of the cellular environment, is becoming a prominent
approach in this field. In this work, we present a non-invasive magnetic on-chip platform which allows
for the manipulation of magnetic particles, through micrometric magnetic conduits of Permalloy patterned
on-chip. We show, from simulations and experiments, that this technology permits to exert a
finely controlled force on magnetic beads along the chip surface. This force can be tuned from few to
hundreds pN by applying a variable external magnetic field
MANAGEMENT DELLO SCHWANNOMA INTRALABIRINTICO
Lo schwannoma intralabirintico (SIL) è un raro tumore benigno (prevalenza 0.1-0.4%) che origina dalle cellule di Schwann perineurali del nervo cocleovestibolare prossimale al labirinto membranoso (coclea, vestibolo o canali semicircolari). E’ stato descritto per la prima volta da Meter nel 1917. I sintomi clinici di esordio includono ipoacusia neurosensoriale monolaterale progressiva (95%) e in alcuni casi improvvisa o fluttuante, acufeni (51%), disequilibrio (35%), vertigine (22%), fullness (2%). Alla risonanza magnetica (RM) il tumore si presenta come una massa circoscritta, ipointensa nelle sequenze T2-pesate e con un forte enhancement dopo somministrazione di gadolinio nelle immagini T1-pesate. Lo SIL si pone in diagnosi differenziale con M. di Meniere o neurite vestibolare. La mancanza di sintomi specifici e il lento pattern di crescita spiega la diagnosi tardiva. Oggigiorno la RM permette una diagnosi sempre più precoce e l’ adozione di un appropriato protocollo terapeutico
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