We demonstrate lasing into counterpropagating modes of a ring cavity using a gas of cold atoms as a gain medium. The laser operates under the usual conditions of magneto-optical trapping with no ...additional fields. We characterize the threshold behavior of the laser and measure the second-order optical coherence. The laser emission exhibits directional bistability, switching randomly between clockwise and counterclockwise modes, and a tunable nonreciprocity is observed as the atoms are displaced along the cavity axis.
We present experiments on ensemble cavity quantum electrodynamics with cold potassium atoms in a high-finesse ring cavity. Potassium-39 atoms are cooled in a two-dimensional magneto-optical trap and ...transferred to a three-dimensional trap which intersects the cavity mode. The apparatus is described in detail and the first observations of strong coupling with potassium atoms are presented. Collective strong coupling of atoms and light is demonstrated via the splitting of the cavity transmission spectrum and the avoided crossing of the normal modes.
Background: It has been reported that KRAS mutations (and to a lesser extent KRAS mutations with the BRAF V600E mutation) negatively affect response to anti-epidermal growth factor receptor (EGFR) ...mAbs in metastatic colorectal cancer (mCRC) patients, while the biological impact of the EGFR pathway represented by PI3K/PTEN/AKT on anti-EGFR treatment is still not clear.
Patients and methods: We analysed formalin-fixed samples from a cohort of 32 mCRC patients treated with cetuximab by means of EGFR immunohistochemistry, EGFR and PTEN FISH analysis, and KRAS, BRAF, PI3KCA, and PTEN genomic sequencing.
Results: Ten (31%) of 32 patients showed a partial response to cetuximab and 22 (69%) did not nonresponder (NR). EGFR immunophenotype and FISH-based gene status did not predict an anti-EGFR mAb response, whereas KRAS mutations (24%) and PI3K pathway activation, by means of PI3KCA mutations (13%) or PTEN mutation (10%)/loss (13%), were significantly restricted to, respectively, 41% and 37% of NRs.
Conclusion: These findings suggested that KRAS mutations and PI3KCA/PTEN deregulation significantly correlate with resistance to cetuximab. In line with this, patients carrying KRAS mutations or with activated PI3K profiles can benefit from targeted treatments only by switching off molecules belonging to the downstream signalling of activated EGFR, such as mammalian target of rapamycin.
In the last years, high-resolution time tagging has emerged as a promising tool to tackle the problem of high-track density in the detectors of the next generation of experiments at particle ...colliders. Time resolutions below 50 ps and event average repetition rates of tens of MHz on sensor pixels having a pitch of 50 μm are typical minimum requirements. This poses an important scientific and technological challenge on the development of particle sensors and processing electronics. The TIMESPOT initiative (which stands for TIME and SPace real-time Operating Tracker) aims at the development of a full prototype detection system suitable for the particle trackers of the next-to-come particle physics experiments. This paper describes the results obtained on the first batch of TIMESPOT silicon sensors, based on a novel 3D MEMS (micro electro-mechanical systems) design. We demonstrate that following this approach, the performance of other ongoing silicon sensor developments can be matched and overcome. In addition, 3D technology has already been proved to be robust against radiation damage. A time resolution of the order of 20 ps has been measured at room temperature suggesting also possible improvements after further optimisations of the front-end electronics processing stage.
Following neoadjuvant chemotherapy for operable gastroesophageal cancer, lymph node metastasis is the only validated prognostic variable; however, within lymph node groups there is still ...heterogeneity with risk of relapse. We hypothesized that gene profiles from neoadjuvant chemotherapy treated resection specimens from gastroesophageal cancer patients can be used to define prognostic risk groups to identify patients at risk for relapse.
The Medical Research Council Adjuvant Gastric Infusional Chemotherapy (MAGIC) trial (n = 202 with high quality RNA) samples treated with perioperative chemotherapy were profiled for a custom gastric cancer gene panel using the NanoString platform. Genes associated with overall survival (OS) were identified using penalized and standard Cox regression, followed by generation of risk scores and development of a NanoString biomarker assay to stratify patients into risk groups associated with OS. An independent dataset served as a validation cohort.
Regression and clustering analysis of MAGIC patients defined a seven-Gene Signature and two risk groups with different OS hazard ratio (HR) 5.1; P < 0.0001. The median OS of high- and low-risk groups were 10.2 95% confidence interval (CI) of 6.5 and 13.2 months and 80.9 months (CI: 43.0 months and not assessable), respectively. Risk groups were independently prognostic of lymph node metastasis by multivariate analysis (HR 3.6 in node positive group, P = 0.02; HR 3.6 in high-risk group, P = 0.0002), and not prognostic in surgery only patients (n = 118; log rank P = 0.2). A validation cohort independently confirmed these findings.
These results suggest that gene-based risk groups can independently predict prognosis in gastroesophageal cancer patients treated with neoadjuvant chemotherapy. This signature and associated assay may help risk stratify these patients for post-surgery chemotherapy in future perioperative chemotherapy-based clinical trials.
Abstract
This paper presents the detailed simulation of a
double-pixel structure for charged particle detection based on the
3D-trench silicon sensor developed for the TIMESPOT project and a
...comparison of the simulation results with measurements performed at
the π-M1 beam at PSI laboratory. The simulation is based on the
combined use of several software tools (TCAD, GEANT4, TCoDe and
TFBoost) which allow to fully design and simulate the device physics
response in very short computational time,
O(1–100 s) per simulated signal, by exploiting
parallel computation using single or multi-thread processors. This
allowed to produce large samples of simulated signals, perform
detailed studies of the sensor characteristics and make precise
comparisons with experimental results.
We discuss the prospects for enhancing absorption and scattering of light from a weakly coupled atom in a high-finesse optical cavity by adding a medium with large, positive group index of ...refraction. The slow-light effect is known to narrow the cavity transmission spectrum and increase the photon lifetime, but the quality factor of the cavity may not be increased in a metrologically useful sense. Specifically, detection of the weakly coupled atom through either cavity ringdown measurements or the Purcell effect fails to improve with the addition of material slow light. A single-atom model of the dispersive medium helps elucidate why this is the case.
Abstract
In this paper the results of a beam test characterization campaign of 3D trench silicon pixel sensors are presented. A time resolution in the order of 10 ps was measured both for ...non-irradiated and irradiated sensors up to a fluence of 2.5 × 10
16
1 MeV n
eq
cm
−2
. This feature and a detection efficiency close to 99% make this sensors one of the best candidates for 4D tracking detectors in High-Energy-Physics experiments.
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