Field-Assisted DC-Pulsed Cathodes for next generation light sources and accelerators

International audienceThe scope of that contribution is to present the challenges of the next particle sources for accelerators. It is admitted that emittance near Interaction Point (IP) is strongly dominated by the emittance of the low power source. To minimize theBremstrahlung effects in the Interaction Point (IP), we also need extremely low emittance bunches, ultra high brillance, very low charges sub fC, near depopulated attosecond electronic bunches. These produced bunches should fit the entrances of Dielectric Laser Accelerators (DLA) and Laser Plasma Accelerators (LPA).A 20kV DC pulsed sub nanosecond Field Emission Array source with extremely low emittance is considered in order to obtain such results. Firstly, we will describe the DC-pulsed experimental source by blocks. Following that, we will raise more general problems induced by DC-pulsed configuration: thermal transient behaviour of nanostructures, enhancement of plasmons coupling in relation to nanostructured networks, then fast prototyping of cathode geometry will be undertaken using different models. These cathodes are to be fabricated at Orsay.We present the method of curvilinear coordinate calculus, adapted to major classes of nanostructured tips. We define 3 major classes of 3D analytical profiles to emulate experimental conditions (multi-segment, quadratic and exponential one) and apply curvilinear analytical Maxwellsolving to find electrostatic potential around the profile. Our method is concurrent to T-splines for instance, but it is expected to converge faster. Cathode physics will be modelled integrating different phenomenons: photo/thermal/field/emission... Results will be compared to electromagnetic simulations with CST and Astra tools. To conclude, we shall then evaluate the emittance performances planned for a 20keV cathodic source, and its acceptance to the next stages, with the help of some electrostatic focusing. Numerous experimental and theoretical aspects are to be solved

RF Coaxial Resonator for Investigating Multipactor Discharges on Metal and Dielectric Surfaces

http://accelconf.web.cern.ch/AccelConf/LINAC2014/html/auth0693.htmTHPP096International audienceMultipactor discharge is a phenomenon in which electrons impact one or more material surfaces in resonance with an alternating electric field. The discharge can occur for a wide range of frequencies, from the MHz range to tens of GHz, and in wide array of geometries if the impacted surface has a secondary electron emission (SEE) yield larger than one. The discharge can take place on a single surface or between two surfaces. A novel coaxial resonator to investigate two-surface multipactor discharges on metal and dielectric surfaces in the gap region under vacuum conditions has been designed and tested. The resonator is ~ 100 mm in length with an outer diameter of ~ 60 mm (internal dimensions). A pulsed RF source delivers up to 30 W average power over a wide frequency range 650-900 MHz to the RF resonator. The incident and reflected RF signals are monitored by calibrated RF diodes. An electron probe provides temporal measurements of the multipacting electron current with respect to the RF power. These experiments were successful in identifying multipacting and allowed us the evaluation of a home made sputtered titanium nitride (TiN) thin layers as a Multipactor suppressor

First Principle Study and Optimal Doping for High Thermoelectric Performance of TaXSn Materials (X = Co, Ir and Rh)

In this paper, the full potential linearized augmented plane wave method implemented in the WIEN2K code with first principles-based density functional theory are used to investigate the structural, elastic, electronic and thermoelectric properties of TaCoSn, TaIrSn and TaRhSn. The structural and elastic constants are calculated using the generalized gradient potential developed by Perdew-Burke-Ernzerhof (GGA-PBEsol). The electronic structures are performed by means of GGA-PBEsol and improved by TranBlaha modified Becke-Johnson (TB-mBJ) potential. Our results show that the studied compounds are semiconductors with indirect gaps. On the other hand, we investigated the thermoelectric properties at different temperatures with respect to the chemical potential. The results show that the thermopower factors are more important for p-type doping than those for n-type doping and the maximum value of these factors indicates the optimal hole-doping level which gives rise to high thermoelectric performances of these materials. Finally, we note that the best thermopower values are found for the TaRhSn compound with optimal doping levels of (75.76, 175.60 and 238.92) x 1014 µW cm – 1 K – 2 s – 1 at temperatures of 300, 600, and 900 K, respectively

Analysis of Blood Cultures in Major Burns in Tertiary Care Burn Unit in Oman

Objectives: In this study we review blood stream infections of major burns in a tertiary care burn unit to determine the most prevalent organisms in order to have a better empirical therapy protocol. Methods: This is a retrospective study where blood stream infection of major burns (>20% Total Body Surface Area) were analysed. Results:155 patients fulfilled the criteria. Median age was 33 years.  Median TBSA was 38%. 57.42% were males and 42.58% were females. Mortality was 25.16%. 50.9% of patients had positive blood culture. Expired patients had higher TBSA, Abbreviated Burns Severity Index score and earlier first positive blood culture. The most prevalent organisms grown from all blood cultures were Acinetobacter, staphylococci, Klebsiella, Enterococcus and pseudomonas. Candida is also commonly grown in blood cultures. All Acinetobacter species are always multidrug resistant. 8 of 14 patients had multidrug resistant Klebsiella.  There were only 4 patients who had Methicilin resistant Staphylococcus Aureus (MRSA) grown. The number of blood cultures samples taken ranged from 1 to 28 (median 6). First positive blood culture showed that Staphylococcus epidermidis   and Acinetobacter are the most common organisms. Conclusion: In conclusion multidrug resistant Acinetobcater has become the most predominant microorganism grown in blood cultures of major burns in our unit. Empirical therapy should include antibiotics that are effective against it to reduce the mortality. Keywords: Infection; Blood; Burn; Resistance; Antibiotics; Culture

Cyclin dependent kinase inhibitor 3 (CDKN3) upregulation is associated with unfavorable prognosis in clear cell renal cell carcinoma and shapes tumor immune microenvironment: A bioinformatics analysis

Cell cycle regulatory proteins plays a pivotal role in the development and progression of many human malignancies. Identification of their biological functions as well as their prognostic utility presents an active field of research. As a continuation of the ongoing efforts to elucidate the molecular characteristics of clear cell renal cell carcinoma (ccRCC); we present a comprehensive bioinformatics study targeting the prognostic and mechanistic role of cyclin-dependent kinase inhibitor 3 (CDKN3) in ccRCC. The ccRCC cohort from the Cancer Genome Atlas Program was accessed through the UCSC Xena browser to obtain CDKN3 mRNA expression data and their corresponding clinicopathological variables. The independent prognostic signature of CDKN3 was evaluated using univariate and multivariate Cox logistic regression analysis. Gene set enrichment analysis and co-expression gene functional annotations were used to discern CDKN3-related altered molecular pathways. The tumor immune microenvironment was evaluated using TIMER 2.0 and gene expression profiling interactive analysis. CDKN3 upregulation is associated with shortened overall survival (hazard ratio [HR] = 2.325, 95% confident interval [CI]: 1.703–3.173, P < .0001) in the Cancer Genome Atlas Program ccRCC cohort. Univariate (HR: 0.426, 95% CI: 0.316–0.576, P < .001) and multivariate (HR: 0.560, 95% CI: 0.409–0.766, P < .001) Cox logistic regression analyses indicate that CDKN3 is an independent prognostic variable of the overall survival. High CDKN3 expression is associated with enrichment within the following pathways including allograph rejection, epithelial–mesenchymal transition, mitotic spindle, inflammatory response, IL-6/JAK/STAT3 signaling, spermatogenesis, TNF-α signaling via NF-kB pathway, complement activation, KRAS signaling, and INF-γ signaling. CDKN3 is also associated with significant infiltration of a wide spectrum of immune cells and correlates remarkably with immune-related genes. CDKN3 is a poor prognostic biomarker in ccRCC that alters many molecular pathways and impacts the tumor immune microenvironment.Scopu

Identification of the calcitonin receptor in osteoarthritic chondrocytes

<p>Abstract</p> <p>Background</p> <p>Preclinical and clinical studies have shown that salmon calcitonin has cartilage protective effects in joint degenerative diseases, such as osteoarthritis (OA). However, the presence of the calcitonin receptor (CTR) in articular cartilage chondrocytes is yet to be identified. In this study, we sought to further investigate the expression of the CTR in naïve human OA articular chondrocytes to gain further confirmation of the existents of the CTR in articular cartilage.</p> <p>Methods</p> <p>Total RNA was purified from primary chondrocytes from articular cartilage biopsies from four OA patients undergoing total knee replacement. High quality cDNA was produced using a dedicated reverse transcription polymerase chain reaction (RT-PCR) protocol. From this a nested PCR assay amplifying the full coding region of the CTR mRNA was completed. Western blotting and immunohistochemistry were used to characterize CTR protein on protein level in chondrocytes.</p> <p>Results</p> <p>The full coding transcript of the CTR isoform 2 was identified in all four individuals. DNA sequencing revealed a number of allelic variants of the gene including two potentially novel polymorphisms: a frame shift mutation, +473del, producing a shorter form of the receptor protein, and a single nucleotide polymorphism in the 3' non coding region of the transcript, +1443 C>T. A 53 kDa protein band, consistent with non-glycosylated CTR isoform 2, was detected in chondrocytes with a similar size to that expressed in osteoclasts. Moreover the CTR was identified in the plasma membrane and the chondrocyte lacuna of both primary chondrocytes and OA cartilage section.</p> <p>Conclusions</p> <p>Human OA articular cartilage chondrocytes do indeed express the CTR, which makes the articular a pharmacological target of salmon calcitonin. In addition, the results support previous findings suggesting that calcitonin has a direct anabolic effect on articular cartilage.</p

The ThomX project status

Work supported by the French Agence Nationale de la recherche as part of the program EQUIPEX under reference ANR-10-EQPX-51, the Ile de France region, CNRS-IN2P3 and Université Paris Sud XI - http://accelconf.web.cern.ch/AccelConf/IPAC2014/papers/wepro052.pdfA collaboration of seven research institutes and an industry has been set up for the ThomX project, a compact Compton Backscattering Source (CBS) based in Orsay - France. After a period of study and definition of the machine performance, a full description of all the systems has been provided. The infrastructure work has been started and the main systems are in the call for tender phase. In this paper we will illustrate the definitive machine parameters and components characteristics. We will also update the results of the different technical and experimental activities on optical resonators, RF power supplies and on the electron gun

Investigation of the direct effects of salmon calcitonin on human osteoarthritic chondrocytes

<p>Abstract</p> <p>Background</p> <p>Calcitonin has been demonstrated to have chondroprotective effects under pre-clinical settings. It is debated whether this effect is mediated through subchondral-bone, directly on cartilage or both in combination. We investigated possible direct effects of salmon calcitonin on proteoglycans and collagen-type-II synthesis in osteoarthritic (OA) cartilage.</p> <p>Methods</p> <p>Human OA cartilage explants were cultured with salmon calcitonin [100 pM-100 nM]. Direct effects of calcitonin on articular cartilage were evaluated by 1) measurement of proteoglycan synthesis by incorporation of radioactive labeled ³⁵SO₄[5 μCi] 2) quantification of collagen-type-II formation by pro-peptides of collagen type II (PIINP) ELISA, 3) QPCR expression of the calcitonin receptor in OA chondrocytes using four individual primer pairs, 4) activation of the cAMP signaling pathway by EIA and, 5) investigations of metabolic activity by AlamarBlue.</p> <p>Results</p> <p>QPCR analysis and subsequent sequencing confirmed expression of the calcitonin receptor in human chondrocytes. All doses of salmon calcitonin significantly elevated cAMP levels (P < 0.01 and P < 0.001). Calcitonin significantly and concentration-dependently [100 pM-100 nM] induced proteoglycan synthesis measured by radioactive ³⁵SO₄incorporation, with a 96% maximal induction at 10 nM (P < 0.001) corresponding to an 80% induction of 100 ng/ml IGF, (P < 0.05). In alignment with calcitonin treatments [100 pM-100 nM] resulted in 35% (P < 0.01) increased PIINP levels.</p> <p>Conclusion</p> <p>Calcitonin treatment increased proteoglycan and collagen synthesis in human OA cartilage. In addition to its well-established effect on subchondral bone, calcitonin may prove beneficial to the management of joint diseases through direct effects on chondrocytes.</p