Electron Cloud Mitigation by Fast Bunch Compression in the CERN PS

A fast transverse instability has been observed with nominal LHC beams in the CERN Proton Synchrotron (PS) in 2006. The instability develops within less than 1 ms, starting when the bunch length decreases below a threshold of 11.5 ns during the RF procedure to shorten the bunches immediately prior to extraction. An alternative longitudinal beam manipulation, double bunch rotation, has been proposed to compress the bunches from 14 ns to the 4 ns required at extraction within 0.9 ms, saving some 4.5 ms with respect to the present compression scheme. The resultant bunch length is found to be equivalent for both schemes. In addition, electron cloud and vacuum measurements confirm that the development of an electron cloud and the onset of an associated fast pressure rise are delayed with the new compression scheme. Beam dynamics simulations and measurements of the double bunch rotation are presented as well as evidence for its beneficial effect from the electron cloud standpoint

Radiation zoning for vacuum equipment of the CERN Large Hadron Collider

Beam losses in high-energy particle accelerators are responsible for beam lifetime degradation. In the LHC beam losses will create a shower of particles while interacting with materials from the beam pipes and surroundings, resulting in a partial activation of material in the tunnel. Efforts have been made during the accelerator design to monitor and to reduce the activation induced by beam losses. Traceability for all vacuum components has been established providing a tool to follow-up individually each component or subcomponents installed in the tunnel, regardless of their future destination e.g. recycling or disposal. In the latter case, the history of vacuum components will allow calculating the beam-induced activation and permit comparisons with in-situ and ex-situ measurements. This zoning will also help to reduce collective and individual radiation doses to personnel during interventions. The paper presents the vacuum system layout and describes the LHC vacuum zoning and its implementation using an ORACLE© database

Stabilizing effect of a double-harmonic RF system in the CERN PS

Motivated by the discussions on scenarios for LHC upgrades, beam studies on the stability of flat bunches in a double-harmonic RF system have been conducted in the CERN Proton Synchrotron (PS). Injecting nearly nominal LHC beam intensity per cycle, 18 bunches are accelerated on harmonic h = 21 to 26GeV with the 10MHz RF system. On the flat-top, all bunches are then transformed to flat bunches by adiabatically adding RF voltage at h = 42 from a 20MHz cavity in anti-phase to the h = 21 system. The voltage ratio V (h42)/V (h21) of about 0.5 was set according to simulations. For the next 140 ms, longitudinal profiles show stable bunches in the double-harmonic RF bucket until extraction. Without the second harmonic component, coupled-bunch oscillations are observed. The flatness of the bunches along the batch is analyzed as a measure of the relative phase error between the RF systems due to beam loading. The results of beam dynamics simulations and their comparison with the measured data are presented

Dependence of e-cloud on the longitudinal bunch profile: studies in the PS & extension to the HL-LHC

Recent studies have shown that the prospects for significantly increasing bunch intensities in the LHC for the luminosity upgrade (HL-LHC) may be severely limited by the available cryogenic cooling capacity and the electron-cloud (EC) driven beam instability. However, it is planned that during the HL-LHC era the bunch intensities in the LHC will go up by nearly a factor of two compared to the LHC-design values. This motivates the exploration of additional EC mitigation techniques that can be adopted in addition to those already in place. Preliminary simulations indicated that long flat bunches can be beneficial over Gaussian bunches to reduce the EC build up. Rigorous studies using realistic bunch profiles have never been done. Therefore, we have undertaken an in-depth investigation in the CERN 26 GeV PS to see if we can validate the previous findings and, in particular, if flattening the bunch can mitigate the EC. Here we present the results from dedicated EC measurements in the PS using a variety of bunch shapes and a comparison with simulations. Finally, we investigate if reshaping the bunch profiles using a 2nd harmonic rf cavity can mitigate EC in the HL-LHC

Whose Science and whose Religion? Reflections on the Relations between Scientific and Religious Worldviews

Arguments about the relationship between science and religion often proceed by identifying a set of essential characteristics of scientific and religious worldviews and arguing on the basis of these characteristics for claims about a relationship of conflict or compatibility between them. Such a strategy is doomed to failure because science, to some extent, and religion, to a much larger extent, are cultural phenomena that are too diverse in their expressions to be characterized in terms of a unified worldview. In this paper I follow a different strategy. Having offered a loose characterization of the nature of science, I pose five questions about specific areas where religious and scientific worldviews may conflict - questions about the nature of faith, the belief in a God or Gods, the authority of sacred texts, the relationship between scientific and religious conceptions of the mind/soul, and the relationship between scientific and religious understandings of moral behavior. My review of these questions will show that they cannot be answered unequivocally because there is no agreement amongst religious believers as to the meaning of important religious concepts. Thus, whether scientific and religious worldviews conflict depends essentially upon whose science and whose religion one is considering. In closing, I consider the implications of this conundrum for science education

The perspective of science and religion in high school biology teachers in Argentina, Brazil and Uruguay: a comparative study

7th World Conference on Educational Sciences, (WCES-2015), 05-07 February 2015, Athens, Greece.The relationship between science and religion has been marked by historically constructed movements of proximity and conflict. We have investigated how high school biology teachers from three countries with different relationships between State and religion, Argentina, Brazil and Uruguay, conceive the science-religion relationship. Uruguay has consolidated secularism, Argentina has an official religion and Brazil calls itself secular, but its secularism is only relative. Fifty high school biology teachers from each country answered the European BIOHEAD-CITIZEN data collection questionnaire, which investigates teachers' conceptions of biological evolution, health, sexuality, and other topics. The question used was "Should science and religion be separate?" Conflict, independence, dialogue and integration categories were considered in the analysis and the results were submitted to parametric testing. Most Uruguayan high school biology teachers tended to agree with the investigated question, with a lower ratio in Brazil, followed by Argentina. Uruguayan teachers tended to be more assertive in their agreement. The main category was partially confirmed as teachers from Uruguay, the country with a greater secular tradition, tended to agree with the separation between science and religion. In Brazil and Argentina, the category was not confirmed. In Brazil, a self-proclaimed secular country, high school biology teachers were more opposed to the separation between science and religion, while in Argentina, a country with an official religion, they supported the possibility of dialogue and integration between them. We concluded that the respondents felt that science and religion should be separate, but trends varied according to the historical and cultural religiosity features of the selected countries, with a partial influence of secularism on the responses.CIEC – Research Centre on Child Studies, IE, UMinho (FCT R&D unit 317), Portuga

Changes in stem cell regulation and epithelial organisation during carcinogenesis and disease progression in gynaecological malignancies

Gynaecological malignancies represent a heterogeneous group of neoplasms with vastly different aetiology, risk factors, molecular drivers, and disease outcomes. From HPV-driven cervical cancer where early screening and molecular diagnostics efficiently reduced the number of advanced-stage diagnosis, prevalent and relatively well-treated endometrial cancers, to highly aggressive and mostly lethal high-grade serous ovarian cancer, malignancies of the female genital tract have unique presentations and distinct cell biology features. Recent discoveries of stem cell regulatory mechanisms, development of organoid cultures, and NGS analysis have provided valuable insights into the basic biology of these cancers that could help advance new-targeted therapeutic approaches. This review revisits new findings on stemness and differentiation, considering main challenges and open questions. We focus on the role of stem cell niche and tumour microenvironment in early and metastatic stages of the disease progression and highlight the potential of patient-derived organoid models to study key events in tumour evolution, the appearance of resistance mechanisms, and as screening tools to enable personalisation of drug treatments

Experimental Studies of Carbon Coatings as Possible Means of Suppressing Beam Induced Electron Multipacting in the CERN SPS

Electron cloud build-up is a major limitation for the operation of the SPS with LHC beam above nominal intensity. These beams are envisaged in the frame of the LHC luminosity upgrade and will be available from the new injectors LPSPL and PS2. A series of studies have been conducted in order to identify possible means to suppress electron multipacting by coating the existing SPS vacuum chambers with thin films of amorphous carbon. After a description of the experimental apparatus installed in the SPS, the results of the tests performed with beam in 2008 will be presented

STABILIZING EFFECT OF A DOUBLE-HARMONIC RF SYSTEM IN THE CERN PS

Abstract Motivated by the discussions on scenarios for LHC upgrades, beam studies on the stability of flat bunches in a double-harmonic RF system have been conducted in the CERN Proton Synchrotron (PS). Injecting nearly nominal LHC beam intensity per cycle, 18 bunches are accelerated on harmonic h = 21 to 26 GeV with the 10 MHz RF system. On the flat-top, all bunches are then transformed to flat bunches by adiabatically adding RF voltage at h = 42 from a 20 MHz cavity in anti-phase to the h = 21 system. The voltage ratio V (h42)/V (h21) of about 0.5 was set according to simulations. For the next 140 ms, longitudinal profiles show stable bunches in the double-harmonic RF bucket until extraction. Without the second harmonic component, coupled-bunch oscillations are observed. The flatness of the bunches along the batch is analyzed as a measure of the relative phase error between the RF systems due to beam loading. The results of beam dynamics simulations and their comparison with the measured data are presented

Safety and dose modification for patients receiving niraparib

Background: Niraparib is a poly(ADP-ribose) polymerase (PARP) inhibitor approved in the United States and Europe for maintenance treatment of adult patients with recurrent epithelial ovarian, fallopian tube, or primary peritoneal cancer who are in complete or partial response to platinum-based chemotherapy. In the pivotal ENGOT-OV16/NOVA trial, the dose reduction rate due to TEAE was 68.9%, and the discontinuation rate due to TEAE was 14.7%, including 3.3% due to thrombocytopenia. A retrospective analysis was performed to identify clinical parameters that predict dose reductions. Patients and methods: All analyses were performed on the safety population, comprising all patients who received at least one dose of study drug. Patients were analyzed according to the study drug consumed (ie, as treated). A predictive modeling method (decision trees) was used to identify important variables for predicting the likelihood of developing grade ≥3 thrombocytopenia within 30 days after the first dose of niraparib and determine cutoff points for chosen variables. Results: Following dose modification, 200 mg was the most commonly administered dose in the ENGOT-OV16/NOVA trial. Baseline platelet count and baseline body weight were identified as risk factors for increased incidence of grade ≥3 thrombocytopenia. Patients with a baseline body weight <77 kg or a baseline platelet count <150,000/μL in effect received an average daily dose approximating 200 mg (median = 207 mg) due to dose interruption and reduction. Progression-free survival in patients who were dose reduced to either 200 mg or 100 mg was consistent with that of patients who remained at the 300 mg starting dose. Conclusions: The analysis presented suggests that patients with baseline body weight of < 77 kg or baseline platelets of < 150,000/μL may benefit from a starting dose of 200 mg per day. (ClinicalTrials.gov ID: NCT01847274)