Gastric carcinoma is one of the most frequent malignancies in the world and its clinical behavior depends on the metastatic potential of the tumour. Particularly, lymphatic metastasis is one of the ...main predictor of tumour recurrence and survival and current pathologic staging systems reflect the concept that lymphatic spread is the most relevant prognostic factor in patients resected with curative intent. This is deducted by the observation that two thirds of gastric cancers in the western world present at an advanced stage, with nearly 85% of tumors accompanied by lymph node metastasis at diagnosis. To date most therapeutic efforts are directed toward individualization of therapeutic protocols, tailoring the extent of resection integrated by the administration of preoperative and postoperative treatment. The goal of such strategies is to improve prognosis towards the achievement of a curative resection (R0-resection) with minimal morbidity and mortality, with better postoperative quality of life. A brief review of literature about preoperative therapy for gastric carcinoma will be herein illustrated. The rationale and the general drawbacks of preoperative treatments will be both discussed in order to demonstrate its value in terms of safety and efficacy.
We report on a search for electronic recoil event rate modulation signatures in the XENON100 data accumulated over a period of 4 yr, from January 2010 to January 2014. A profile likelihood method, ...which incorporates the stability of the XENON100 detector and the known electronic recoil background model, is used to quantify the significance of periodicity in the time distribution of events. There is a weak modulation signature at a period of 431_{-14}^{+16} day in the low energy region of (2.0-5.8) keV in the single scatter event sample, with a global significance of 1.9σ; however, no other more significant modulation is observed. The significance of an annual modulation signature drops from 2.8σ, from a previous analysis of a subset of this data, to 1.8σ with all data combined. Single scatter events in the low energy region are thus used to exclude the DAMA/LIBRA annual modulation as being due to dark matter electron interactions via axial vector coupling at 5.7σ.
The XENON1T dark matter experiment aims to detect weakly interacting massive particles (WIMPs) through low-energy interactions with xenon atoms. To detect such a rare event necessitates the use of ...radiopure materials to minimize the number of background events within the expected WIMP signal region. In this paper we report the results of an extensive material radioassay campaign for the XENON1T experiment. Using gamma-ray spectroscopy and mass spectrometry techniques, systematic measurements of trace radioactive impurities in over one hundred samples within a wide range of materials were performed. The measured activities allowed for stringent selection and placement of materials during the detector construction phase and provided the input for XENON1T detection sensitivity estimates through Monte Carlo simulations.
The low-background, VUV-sensitive 3-inch diameter photomultiplier tube R11410 has been developed by Hamamatsu for dark matter direct detection experiments using liquid xenon as the target material. ...We present the results from the joint effort between the XENON collaboration and the Hamamatsu company to produce a highly radio-pure photosensor (version R11410-21) for the XENON1T dark matter experiment. After introducing the photosensor and its components, we show the methods and results of the radioactive contamination measurements of the individual materials employed in the photomultiplier production. We then discuss the adopted strategies to reduce the radioactivity of the various PMT versions. Finally, we detail the results from screening 286 tubes with ultra-low background germanium detectors, as well as their implications for the expected electronic and nuclear recoil background of the XENON1T experiment.
The XENON1T experiment aims for the direct detection of dark matter in a detector filled with 3.3 tons of liquid xenon. In order to achieve the desired sensitivity, the background induced by ...radioactive decays inside the detector has to be sufficiently low. One major contributor is the
β
-emitter
85
Kr which is present in the xenon. For XENON1T a concentration of natural krypton in xenon
nat
Kr
/
Xe
<
200
ppq
(parts per quadrillion,
1
ppq
=
10
-
15
mol
/
mol
) is required. In this work, the design, construction and test of a novel cryogenic distillation column using the common McCabe–Thiele approach is described. The system demonstrated a krypton reduction factor of
6.4
·
10
5
with thermodynamic stability at process speeds above 3 kg/h. The resulting concentration of
nat
Kr
/
Xe
<
26
ppq
is the lowest ever achieved, almost one order of magnitude below the requirements for XENON1T and even sufficient for future dark matter experiments using liquid xenon, such as XENONnT and DARWIN.
The present study is a prospective evaluation of immediate preoperative laparoscopy compared to ultrasound/computed tomography (US/CT) staging for gastric cancer in a series of 100 patients observed ...at two major Italian hospitals from April 1995 through September 1996.
After a complete preoperative work-up all c-M0 patients underwent laparoscopy immediately prior to an eventual surgical exploration. pTNM was considered as the gold standard for the evaluation of the results.
Laparoscopy detected 21 unsuspected M+ cases out of 100. As regards locally advanced tumors, laparoscopy showed a sensibility of 69.7% for T3 and 89.6% for T4, significantly higher than US/CT staging (23.2% and 48.3%, respectively; p < 0.02). In this series laparoscopic staging altered clinical staging in 58% of cases.
This procedure plays two crucial roles in the preoperative evaluation of advanced gastric cancer: It makes it possible to avoid unnecessary surgical exploration in M+ cases and, to date, it represents the most reliable and economic tool for the selection of locally advanced tumors in the light of neoadjuvant treatment.
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