Deep XMM Observations of Draco rule out at the 99% Confidence Level a Dark Matter Decay Origin for the 3.5 keV Line

We searched for an X-ray line at energies around 3.5 keV in deep, ~1.6 Msec XMM-Newton observations of the dwarf spheroidal galaxy Draco. No line was found in either the MOS or the PN detectors. The data in this energy range are completely consistent with a single, unfolded power law modeling the particle background, which dominates at these energies, plus instrumental lines; the addition of a ~3.5 keV line feature gives no improvement to the fit. The corresponding upper limit on the line flux rules out a dark matter decay origin for the 3.5 keV line found in observations of clusters of galaxies and in the Galactic Center at greater than 99% C.L..Comment: 5 pages, 3 figures, accepted for publication in Monthly Notices of the Royal Astronomical Society; includes new discussion on Ruchayskiy et al (2015), arXiv:1512.0721

Enhancing Trust in eAssessment - the TeSLA System Solution

Trust in eAssessment is an important factor for improving the quality of online-education. A comprehensive model for trust based authentication for eAssessment is being developed and tested within the score of the EU H2020 project TeSLA. The use of biometric verification technologies to authenticate the identity and authorship claims of individual students in online-education scenarios is a significant component of TeSLA. Technical Univerity of Sofia (TUS) Bulgaria, a member of TeSLA consortium, participates in large-scale pilot tests of the TeSLA system. The results of questionnaires to students and teachers involved in the TUS pilot tests are analyzed and summarized in this work. We also describe the TeSLA authentication and fraud-detection instruments and their role for enhancing trust in eAssessment.Comment: Presented at the Conference on Technology Enhanced Assessment (TEA), 2018. 18 pages, 2 tables, 3 figure

A Pixel Vertex Tracker for the TESLA Detector

In order to fully exploit the physics potential of a e+e- linear collider, such as TESLA, a Vertex Tracker providing high resolution track reconstruction is required. Hybrid Silicon pixel sensors are an attractive sensor technology option due to their read-out speed and radiation hardness, favoured in the high rate TESLA environment, but have been so far limited by the achievable single point space resolution. A novel layout of pixel detectors with interleaved cells to improve their spatial resolution is introduced and the results of the characterisation of a first set of test structures are discussed. In this note, a conceptual design of the TESLA Vertex Tracker, based on hybrid pixel sensors is presentedComment: 20 pages, 11 figure

Quantum limit transport and destruction of the Weyl nodes in TaAs

Weyl fermions are a new ingredient for correlated states of electronic matter. A key difficulty has been that real materials also contain non-Weyl quasiparticles, and disentangling the experimental signatures has proven challenging. We use magnetic fields up to 95 tesla to drive the Weyl semimetal TaAs far into its quantum limit (QL), where only the purely chiral 0th Landau levels (LLs) of the Weyl fermions are occupied. We find the electrical resistivity to be nearly independent of magnetic field up to 50 tesla: unusual for conventional metals but consistent with the chiral anomaly for Weyl fermions. Above 50 tesla we observe a two-order-of-magnitude increase in resistivity, indicating that a gap opens in the chiral LLs. Above 80 tesla we observe strong ultrasonic attenuation below 2 kelvin, suggesting a mesoscopically-textured state of matter. These results point the way to inducing new correlated states of matter in the QL of Weyl semimetals

Physics at TESLA

The physics at a 500-800 GeV electron positron linear collider, TESLA, is reviewed. The machine parameters that impact directly on the physics are discussed and a few key performance goals for a detector at TESLA are given. Emphasis is placed on precision measurements in the Higgs and top sectors and on extrapolation to high energy scales in the supersymmetric scenario.Comment: Talk presented at Lake Louise Winter Institute 2001. 7 pages, 2 figure

The use of recombinant DNA technology in producing pharmaceuticals

Rekombinantna DNA tehnologija podrazumijeva metode kojima možemo prenijeti gene iz jednog organizma u drugi. Time se omogućava dobivanje proteina u organizmima u kojima se ti proteini prirodno ne stvaraju. Takva tehnologija danas ima brojne primjene, a jedna od njih je proizvodnja lijekova. Prvi ljudski protein dobiven iz bakterije E. coli bio je inzulin, 1982. godine. Danas se za manipulaciju gena u svrhu dobivanja rekombinantnih proteina, osim bakterija, koriste i kvasci, životinje, biljke te stanične kulture. Svaka metoda proizvodnje ima svoje prednosti i nedostatke. Glavni nedostatak bakterijama je nemogućnost glikozilacije proteina. Kvasci, kao eukarioti, uspješniji su u tom procesu. Transgenične životinje mogu izlučivati znatne količine proteina u krv, mlijeko, bjelanjak ili urin. Mogu proizvoditi proteine složenih struktura koji moraju proći proces posttranslacijske modifikacije da bi postali aktivni. Upotreba transgeničnih životinja postavlja brojna etička pitanja te pitanja vezana uz sigurnost pripreme takvih proteina. Transgenične biljke mogu proizvoditi velike količine proteina te stvarati proteine kompleksnih struktura. Također takva je proizvodnja jeftina i nema gotovo nikakvih etičkih problema. Najveći nedostatak genetički modificiranih organizama je interakcija s okolišem. Unatoč tome što još uvijek malo znamo o tome kakav bi učinak transgenični organizmi mogli imati na svoj okoliš, možemo reći da je rekombinantna DNA tehnologija u proizvodnji lijekova svojevrsno čudo 20.-og stoljeća.Recombinant DNA technology encompasses various techniques by which we can transfer genes from one organism to another. This way we accomplished production of proteins in organisms for which these proteins are not natural. Such technology has many applications today. One of them is the use in producing pharmaceuticals. Proteins play an important role in the pharmaceutical industry. The first human protein produced in Escherichia coli was insulin, in 1982. Today, we use biotechnology in order to obtain recombinant proteins from bacteria, yeasts, animals, plants and cell cultures. Each manufacturing method has its advantages and disadvantages. The major drawback of bacteria is that they are unable to perform the posttranslation modifications such as glycosylation. Yeasts, as eukaryotes, have some advantages over bacteria in this process. Transgenic animals can secrete significant amounts of protein in blood, milk, egg white or urine. They can also produce proteins with complex structure that must undergo a process of posttranslational modifications. The use of transgenic animals faces many ethical issues and issues of environmental impact of such animals. Transgenic plants can produce large amounts of protein and they can also form complex protein structures. This system of production is cheap and avoids some ethical issues. The biggest disadvantage is interaction with the environment. Although we still know little about how transgenic organisms could affect the nature one day, we can say that the recombinant DNA technology in the production of pharmaceuticals is sort of a miracle of the 20th century