Electronic compressibility of layer polarized bilayer graphene

We report on a capacitance study of dual gated bilayer graphene. The measured capacitance allows us to probe the electronic compressibility as a function of carrier density, temperature, and applied perpendicular electrical displacement D. As a band gap is induced with increasing D, the compressibility minimum at charge neutrality becomes deeper but remains finite, suggesting the presence of localized states within the energy gap. Temperature dependent capacitance measurements show that compressibility is sensitive to the intrinsic band gap. For large displacements, an additional peak appears in the compressibility as a function of density, corresponding to the presence of a 1-dimensional van Hove singularity (vHs) at the band edge arising from the quartic bilayer graphene band structure. For D > 0, the additional peak is observed only for electrons, while D < 0 the peak appears only for holes. This asymmetry that can be understood in terms of the finite interlayer separation and may be useful as a direct probe of the layer polarization

MET nucleotide variations and amplification in advanced ovarian cancer: characteristics and outcomes with c-Met inhibitors.

PurposeMET alterations including amplifications and nucleotide variations have been associated with resistance to therapy and aggressive clinical behavior.Experimental designThe medical records of patients presenting to the University of Texas MD Anderson Cancer Center Phase I Clinic with relapsed or metastatic ovarian cancers and known MET nucleotide variation or amplification status were reviewed retrospectively (n=178). Categorical and continuous clinical and molecular characteristics were compared using Fisher's exact and Wilcoxon rank-sum tests, respectively. Univariate and multivariate survival were assessed via Kaplan-Meier and Cox regression analysis, respectively.ResultsMET amplification occurred in 4 (3.5%) of 113 patients, whereas nonsynonomous nucleotide variations were present in 9 (7.4%) of 122 patients. No patients exhibited concomitant amplification and variation. MET variations were observed only in white women with high-grade ovarian tumors, whereas amplifications were observed in both black and white women with high-grade serous ovarian primary tumors. No patients (n=4) exhibiting a MET alteration achieved an objective response when treated on a c-Met inhibitor phase I trial. In addition, ovarian cancer patients treated with a c-Met inhibitor with multikinase activity trended towards a longer time-to-failure compared with those treated with a c-Met-specific inhibitor (median: 1.5 vs. 4.5 months, p=0.07).ConclusionsMET alterations occur in a minority of patients with ovarian cancer. c-Met inhibitors with multikinase activity may exhibit less activity in ovarian cancer than c-Met specific drugs. These findings warrant further investigation

Proton tracking in a high-granularity Digital Tracking Calorimeter for proton CT purposes

Radiation therapy with protons as of today utilizes information from x-ray CT in order to estimate the proton stopping power of the traversed tissue in a patient. The conversion from x-ray attenuation to proton stopping power in tissue introduces range uncertainties of the order of 2-3% of the range, uncertainties that are contributing to an increase of the necessary planning margins added to the target volume in a patient. Imaging methods and modalities, such as Dual Energy CT and proton CT, have come into consideration in the pursuit of obtaining an as good as possible estimate of the proton stopping power. In this study, a Digital Tracking Calorimeter is benchmarked for proof-of-concept for proton CT purposes. The Digital Tracking Calorimeteris applied for reconstruction of the tracks and energies of individual high energy protons. The presented prototype forms the basis for a proton CT system using a single technology for tracking and calorimetry. This advantage simplifies the setup and reduces the cost of a proton CT system assembly, and it is a unique feature of the Digital Tracking Calorimeter. Data from the AGORFIRM beamline at KVI-CART in Groningen in the Netherlands and Monte Carlo simulation results are used to in order to develop a tracking algorithm for the estimation of the residual ranges of a high number of concurrent proton tracks. The range of the individual protons can at present be estimated with a resolution of 4%. The readout system for this prototype is able to handle an effective proton frequency of 1 MHz by using 500 concurrent proton tracks in each readout frame, which is at the high end range of present similar prototypes. A future further optimized prototype will enable a high-speed and more accurate determination of the ranges of individual protons in a therapeutic beam.Comment: 21 pages, 8 figure

Retreatment with anti-EGFR based therapies in metastatic colorectal cancer: impact of intervening time interval and prior anti-EGFR response.

BackgroundThis retrospective study aims to investigate the activity of retreatment with anti-EGFR-based therapies in order to explore the concept of clonal evolution by evaluating the impact of prior activity and intervening time interval.MethodsEighty-nine KRAS exon 2-wild-type metastatic colorectal patients were retreated on phase I/II clinical trials containing anti-EGFR therapies after progressing on prior cetuximab or panitumumab. Response on prior anti-EGFR therapy was defined retrospectively per physician-records as response or stable disease ≥6 months. Multivariable statistical methods included a multiple logistic regression model for response, and Cox proportional hazards model for progression-free survival.ResultsRetreatment anti-EGFR agents were cetuximab (n = 76) or cetuximab plus erlotinib (n = 13). The median interval time between prior and retreatment regimens was 4.57 months (range: 0.46-58.7). Patients who responded to the prior cetuximab or panitumumab were more likely to obtain clinical benefit to the retreatment compared to the non-responders in both univariate (p = 0.007) and multivariate analyses (OR: 3.38, 95 % CI: 1.27, 9.31, p = 0.019). The clinical benefit rate on retreatment also showed a marginally significant association with interval time between the two anti-EGFR based therapies (p = 0.053). Median progression-free survival on retreatment was increased in prior responders (4.9 months, 95 % CI: 3.6, 6.2) compared to prior non-responders (2.5 months, 95 % CI, 1.58, 3.42) in univariate (p = 0.064) and multivariate analysis (HR: 0.70, 95 % CI: 0.43-1.15, p = 0.156).ConclusionOur data lends support to the concept of clonal evolution, though the clinical impact appears less robust than previously reported. Further work to determine which patients benefit from retreatment post progression is needed

Creatives after the crash

We examine recent evidence concerning the fate of creative workers since the economic crash of 2007-2008. There is some consensus that the creative economy is an important economic driver and does represent a source of fundamental economic change. There is less agreement on what this change means for the creative worker and workforce. Some studies suggest that the creative workforce has weathered the storm much better than those in lower-order service and manufacturing occupations. Others challenge this finding and some studies point to the growing precariousness and vulnerability of creative work. What does seem clear is that the nature and degree of vulnerability is shaped and influenced by the wider macro-institutional architectures within which this economic activity is situated

The response of benthic foraminifer, ostracod and mollusc assemblages to environmental conditions: a case study from the Camalti Saltpan (Izmir-Western Turkey)

The subject of this report is benthic foraminifer populations preserved in the saltpan of Camalti in the Province of Izmir. High salinity in certain habitats of Ammonia tepida Cushman may be the primary cause of the high rate of twins and triplets as well as other morphological abnormalities recorded within this species (50 % as compared to an anomaly rate of 1 % in normal marine waters). Thicker cyst membrane developing in extremely saline environments may encourage twins and other morphological deformities by denying free movement of the offspring. Ecological factors such as heavy metal contamination of ambient waters as well as contamination by other wastes are also not ruled out as leading to such developmental anomalies. Of the 27 collected samples, Number 5 (that is closest to the sea) includes the typical marine foraminifers. Nonion depressulum (Walker & Jacob), Ammonia tepida Cushman and Porosononion subgronosum(Egger) are the dominant species in other samples. A total of 63 abnormal individuals (8 triplets, 24 twins, and 31 morphological anomalies) was found within seven of the 27 samples collected. Ten samples contained freshwater ostracods: Darwinula stevensoni(Brady and Robertson), Leptocythere lacertosa Hirschmann, Cyprideis torasa (Jones), Cyprideis (C.) anatolica Bassiouni, and Loxochoncha elliptica Brady. Among these samples (some of which contained only a few species of ostracods - and those limited in number of offspring), one had an unusually high ratio of healthy foraminifers vs those with anomalies. Worthy of note in another sample was a high abundance of molluscs. Among pelecypods, were found Ostrea edulis Linné, Lucinella divaricata (Linné), Pseudocama gryphina Lamarck,Cerastoderma edule (Linné), and Scrobicularia plana da Costa; and among gastropods were identified Hydrobi (Hydrobia) acuta(Draparnaud), Rissoa labiosa (Montagu), R. parva (da Costa), R. violacea Desmarest, Pirenella conica (Blainville), Bittium desayesi(Cerulli and Irelli), B. lacteum Philippi and B. reticulatum Philippi