385 research outputs found
Inflation Dynamics and the Cross-Sectional Distribution of Prices in the E.U. Periphery
We explore the connection between inflation and its higher-order moments for three economies in the periphery of the European Union (E.U.), Greece, Portugal and Spain. Motivated by a micro-founded model of inflation determination, along the lines of the hybrid New Keynesian Phillips curve, we examine whether and how much does the cross-sectional skewness in producer prices affect the path of inflation. We develop our analysis with the perspective of economic integration/inflation harmonization (in the E.U.) and discuss the peculiarities of these three economies. We find evidence of a strong positive relation between aggregate inflation and the distribution of relative-price changes for all three countries. A potentially important implication of our results is that, if the cross-sectional skewness of prices is directly related to aggregate inflation, not only the direction but also the magnitude of a nominal shock would influence output and inflation dynamics. Moreover, the effect of such a shock could be received asymmetrically, even when countries share a common currency.Inflation; Cross-sectional distribution of prices; Greece, Portugal, Spain; European Union; Harmonization.
Design of the Target Dump Injection Segmented (TDIS) in the framework of the High Luminosity Large Hadron Collider (HL-LHC) project
The High Luminosity Large Hadron Collider (HL-LHC) Project at CERN calls for increasing beam brightness and intensity. In this scenario, most equipment has to be redesigned and rebuilt. In particular, beam intercepting devices (such as dumps, collimators, absorbers and scrapers) have to withstand impact or scraping of the new intense HL-LHC beams without failure. Furthermore, minimizing the electromagnetic beam-device interactions is also a key design driver since they can lead to beam instabilities and excessive thermo-mechanical loading of devices. In this context, the present study assesses the conceptual design quality of the new LHC injection protection absorber, the Target Dump Injection Segmented (TDIS), from an electromagnetic and thermo-mechanical perspective. This contribution analyzes the thermo-mechanical response of the device considering two cases: an accidental beam impact scenario and another accidental scenario with complete failure of the RFcontacts.
In addition, this paper presents the preliminary results from the simulation of the energy deposited by the two counter-rotating beams circulating in the device
Laser-Induced Linear Electron Acceleration in Free Space
Linear acceleration in free space is a topic that has been studied for over
20 years, and its ability to eventually produce high-quality, high energy
multi-particle bunches has remained a subject of great interest. Arguments can
certainly be made that such an ability is very doubtful. Nevertheless, we chose
to develop an accurate and truly predictive theoretical formalism to explore
this remote possibility in a computational experiment. The formalism includes
exact treatment of Maxwell's equations, exact relativistic treatment of the
interaction among the multiple individual particles, and exact treatment of the
interaction at near and far field. Several surprising results emerged. For
example, we find that 30 keV electrons (2.5% energy spread) can be accelerated
to 7.7 MeV (2.5% spread) and to 205 MeV (0.25% spread) using 25 mJ and 2.5 J
lasers respectively. These findings should hopefully guide and help develop
compact, high-quality, ultra-relativistic electron sources, avoiding
conventional limits imposed by material breakdown or structural constraints.Comment: Supplementary Information starts on pg 1
Areas of Non-Consensus Around One Anastomosis/Mini Gastric Bypass (OAGB/MGB): A Narrative Review
One anastomosis/mini gastric bypass (OAGB/MGB) is now an established bariatric and metabolic surgical procedure with good outcomes. Despite two recent consensus statements around OAGB/MGB, there are some issues which are not accepted as consensus and need more long-term data and research
Compact x-ray source based on burst-mode inverse Compton scattering at 100 kHz
A design for a compact x-ray light source (CXLS) with flux and brilliance
orders of magnitude beyond existing laboratory scale sources is presented. The
source is based on inverse Compton scattering of a high brightness electron
bunch on a picosecond laser pulse. The accelerator is a novel high-efficiency
standing-wave linac and RF photoinjector powered by a single ultrastable RF
transmitter at x-band RF frequency. The high efficiency permits operation at
repetition rates up to 1 kHz, which is further boosted to 100 kHz by operating
with trains of 100 bunches of 100 pC charge, each separated by 5 ns. The entire
accelerator is approximately 1 meter long and produces hard x-rays tunable over
a wide range of photon energies. The colliding laser is a Yb:YAG solid-state
amplifier producing 1030 nm, 100 mJ pulses at the same 1 kHz repetition rate as
the accelerator. The laser pulse is frequency-doubled and stored for many
passes in a ringdown cavity to match the linac pulse structure. At a photon
energy of 12.4 keV, the predicted x-ray flux is
photons/second in a 5% bandwidth and the brilliance is in pulses with RMS pulse
length of 490 fs. The nominal electron beam parameters are 18 MeV kinetic
energy, 10 microamp average current, 0.5 microsecond macropulse length,
resulting in average electron beam power of 180 W. Optimization of the x-ray
output is presented along with design of the accelerator, laser, and x-ray
optic components that are specific to the particular characteristics of the
Compton scattered x-ray pulses.Comment: 25 pages, 24 figures, 54 reference
Electron beam shaping via laser heater temporal shaping
Active longitudinal beam optics can help FEL facilities achieve cutting edge
performance by optimizing the beam to: produce multi-color pulses, suppress
caustics, or support attosecond lasing. As the next generation of
superconducting accelerators comes online, there is a need to find new elements
which can both operate at high beam power and which offer multiplexing
capabilities at Mhz repetition rate. Laser heater shaping promises to satisfy
both criteria by imparting a programmable slice-energy spread on a shot-by-shot
basis. We use a simple kinetic analysis to show how control of the slice energy
spread translates into control of the bunch current profile, and then we
present a collection of start-to-end simulations at LCLS-II in order to
illustrate the technique.Comment: 12 pages, 11 figure
Terahertz Generation in Lithium Niobate Driven by Ti:Sapphire Laser Pulses and its Limitations
We experimentally investigate the limits to 800 nm-to-terahertz (THz) energy
conversion in lithium niobate at room temperature driven by amplified
Ti:Sapphire laser pulses with tilted-pulse-front. The influence of the pump
central wavelength, pulse duration, and fluence on THz generation is studied.
We achieved a high peak efficiency of 0.12% using transform limited 150 fs
pulses and observed saturation of the optical to THz conversion efficiency at a
fluence of 15 mJ/cm2. We experimentally identify two main limitations for the
scaling of optical-to-THz conversion efficiencies: (i) the large spectral
broadening of the optical pump spectrum in combination with large angular
dispersion of the tilted-pulse-front and (ii) free-carrier absorption of THz
radiation due to multi-photon absorption of the 800 nm radiation.Comment: 4 pages, 6 figure
Deubiquitinating enzyme amino acid profiling reveals a class of ubiquitin esterases
The reversibility of ubiquitination by the action of deubiquitinating enzymes (DUBs) serves as an important regulatory layer within the ubiquitin system. Approximately 100 DUBs are encoded by the human genome, and many have been implicated with pathologies, including neurodegeneration and cancer. Non-lysine ubiquitination is chemically distinct, and its physiological importance is emerging. Here, we couple chemically and chemoenzymatically synthesized ubiquitinated lysine and threonine model substrates to a mass spectrometry-based DUB assay. Using this platform, we profile two-thirds of known catalytically active DUBs for threonine esterase and lysine isopeptidase activity and find that most DUBs demonstrate dual selectivity. However, with two anomalous exceptions, the ovarian tumor domain DUB class demonstrates specific (iso)peptidase activity. Strikingly, we find the Machado–Joseph disease (MJD) class to be unappreciated non-lysine DUBs with highly specific ubiquitin esterase activity rivaling the efficiency of the most active isopeptidases. Esterase activity is dependent on the canonical catalytic triad, but proximal hydrophobic residues appear to be general determinants of non-lysine activity. Our findings also suggest that ubiquitin esters have appreciable cellular stability and that non-lysine ubiquitination is an integral component of the ubiquitin system. Its regulatory sophistication is likely to rival that of canonical ubiquitination.We thank Axel Knebel, Richard Ewan, Clare Johnson, and Daniel Fountaine from the Medical Research Council (MRC) Protein Production and Assay Development team, and MRC Reagents and Services, who all contributed to the generation of protein reagents required for the MALDI-TOF DUB assay platform. We thank Ronald Hay for provision of the plasmid encoding the constitutively active RNF4 E3 ligase. This work was funded by the United Kingdom MRC (MC_UU_12016/8), the Biotechnology and Biological Sciences Research Council (BB/P003982/1), and The Michael J. Fox Foundation (12756). We also acknowledge pharmaceutical companies supporting the Division of Signal Transduction Therapy (Boehringer-Ingelheim, GlaxoSmithKline, and Merck KGaA).Peer reviewe
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Comparing serial X-ray crystallography and microcrystal electron diffraction (MicroED) as methods for routine structure determination from small macromolecular crystals.
Innovative new crystallographic methods are facilitating structural studies from ever smaller crystals of biological macromolecules. In particular, serial X-ray crystallography and microcrystal electron diffraction (MicroED) have emerged as useful methods for obtaining structural information from crystals on the nanometre to micrometre scale. Despite the utility of these methods, their implementation can often be difficult, as they present many challenges that are not encountered in traditional macromolecular crystallography experiments. Here, XFEL serial crystallography experiments and MicroED experiments using batch-grown microcrystals of the enzyme cyclophilin A are described. The results provide a roadmap for researchers hoping to design macromolecular microcrystallography experiments, and they highlight the strengths and weaknesses of the two methods. Specifically, we focus on how the different physical conditions imposed by the sample-preparation and delivery methods required for each type of experiment affect the crystal structure of the enzyme
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