Phase-locking of time-delayed attosecond XUV pulse pairs

We present a setup for the generation of phase-locked attosecond extreme ultraviolet (XUV) pulse pairs. The attosecond pulse pairs are generated by high harmonic generation (HHG) driven by two phase-locked near-infrared (NIR) pulses that are produced using an actively stabilized Mach-Zehnder interferometer compatible with near-single cycle pulses. The attosecond XUV pulses can be delayed over a range of 400 fs with a sub-10-as delay jitter. We validate the precision and the accuracy of the setup by XUV optical interferometry and by retrieving the energies of Rydberg states of helium in an XUV pump–NIR probe photoelectron spectroscopy experiment

På rätt spår: återkoppling för lärande i kontrollrumsmiljö - En fallstudie på en svensk järnvägsoperatör

Organisational learning is assumed to be a part of creating improved work processes in an organisation. This type of learning can be difficult to achieve in operational and reactive work environments. Challenges in observable causality, time constraints and complex external conditions means that the operational control room is one of those reactive work environments. There is a need for a system that can improve organisational learning in the challenging environment of the operational control room. The system must create conditions for feedback and evaluation in the operational control room in order to succeed. In this study a manual is created and applied to generate a feedback system, which responds to the control room’s needs. The manual is designed to address the specific conditions that apply in a generic control room. The study was divided into two parts; the first part consisted of a literature review of organizational learning, evaluation and feedback. This was combined with a field study of various control rooms. Knowledge gained from the literature review and the field study was combined to create the manual. Part two of the study consisted of a evaluation of the developed manual on a case company in the Swedish railway industry. An analysis of the case study led to an improved version of the manual. This approach generated both tangible and academic results. The tangible result is a feedback system created using the manual on the case company. The academic results are a new combination the research topic organizational learning and the empirical field of operational control rooms. These have provided a greater understanding of the challenges related to learning that is in operational control room. The authors believe that the manual can be used to develop organisational learning in control rooms in the future.A long term solution to the Swedish railway problem A new learning tool for control room staff has been developed at Lund University. It was tested on a Swedish railway company and can provide a long term improvement of control rooms worldwide. It is well known that the Swedish railway is facing big challenges. The trains are often delayed due to different kinds of disturbances. The headline: “Train Chaos!” is often occurring in Swedish press. The problems arise due to the increased number of travellers and poor maintenance of the railroads and infrastructure. This, together with frequent winter storms that collapse the railroad system, has led to a decreased confidence in railway as mean for transportation. According to statistics gathered by one of the biggest train companies in Sweden, only 20 % of the delays are caused by train breakdowns and 75 % is caused by broken railway. Delays caused by weather can account for about 5 %. Nevertheless, it is the railway company’s responsibility to ensure that travellers reach their destinations and are taken care of when a delay occur. This can be a complex task, as passengers hop on and off on different stations. Moreover, some passengers may have connections to other destinations which can be easily broken with a delay. To be able to take care of the passengers of delayed trains the train companies set up so called control rooms. The employees of the control room keeps track of the different trains and their passengers. Similar kinds of unpredictable problems arise in other types of control rooms. These kinds of working environments can be found at airports, nuclear power plants and big process plants. All of them are monitoring an unpredictable system and try to minimize the damage if anything goes wrong. It is hard to prepare for and learn from this kind of reactive environment. The authors were surprised to discover that people working in control rooms rarely know when they have done a good job and handled the situation in a good way. In order to solve this problem a guide to creating a better learning environment in control rooms was made. The guide is based on current research on learning and feedback. The guide was successfully used by a Swedish railway company. The authors believe that the guide could, if used wisely, provide a long term improvement of control rooms worldwide

High power, high repetition rate laser-based sources for attosecond science

Within the last two decades attosecond science has been established as a novel research field providing insights into the ultrafast electron dynamics that follows a photoexcitation or photoionization process. Enabled by technological advances in ultrafast laser amplifiers, attosecond science has been in turn, a powerful engine driving the development of novel sources of intense ultrafast laser pulses. This article focuses on the development of high repetition rate laser-based sources delivering high energy pulses with a duration of only a few optical cycles, for applications in attosecond science. In particular, a high power, high repetition rate optical parametric chirped pulse amplification system is described, which was developed to drive an attosecond pump-probe beamline targeting photoionization experiments with electron-ion coincidence detection at high acquisition rates

Generation and characterization of isolated attosecond pulses at 100 kHz repetition rate

The generation of coherent light pulses in the extreme ultraviolet (XUV) spectral region with attosecond pulse durations constitutes the foundation of the field of attosecond science. Twenty years after the first demonstration of isolated attosecond pulses, they continue to be a unique tool enabling the observation and control of electron dynamics in atoms, molecules, and solids. It has long been identified that an increase in the repetition rate of attosecond light sources is necessary for many applications in atomic and molecular physics, surface science, and imaging. Although high harmonic generation (HHG) at repetition rates exceeding 100 kHz, showing a continuum in the cutoff region of the XUV spectrum, was already demonstrated in 2013, the number of photons per pulse was insufficient to perform pulse characterization via attosecond streaking, let alone to perform a pump-probe experiment. Here we report on the generation and full characterization of XUV attosecond pulses via HHG driven by near-single-cycle pulses at a repetition rate of 100 kHz. The high number of 106 XUV photons per pulse on target enables attosecond electron streaking experiments through which the XUV pulses are determined to consist of a dominant single attosecond pulse. These results open the door for attosecond pump-probe spectroscopy studies at a repetition rate 1 or 2 orders of magnitude above current implementations

A cascading activity-based probe sequentially targets E1–E2–E3 ubiquitin enzymes

Post-translational modifications of proteins with ubiquitin (Ub) and ubiquitin-like modifiers (Ubls), orchestrated by a cascade of specialized E1, E2 and E3 enzymes, control a wide range of cellular processes. To monitor catalysis along these complex reaction pathways, we developed a cascading activity-based probe, UbDha. Similarly to the native Ub, upon ATP-dependent activation by the E1, UbDha can travel downstream to the E2 (and subsequently E3) enzymes through sequential trans-thioesterifications. Unlike the native Ub, at each step along the cascade, UbDha has the option to react irreversibly with active site cysteine residues of target enzymes, thus enabling their detection. We show that our cascading probe 'hops' and 'traps' catalytically active Ub-modifying enzymes (but not their substrates) by a mechanism diversifiable to Ubls. Our founder methodology, amenable to structural studies, proteome-wide profiling and monitoring of enzymatic activity in living cells, presents novel and versatile tools to interrogate Ub and Ubl cascades.publishe

Nonalcoholic fatty liver disease and reduced serum vitamin D3 levels. (Review)

Nonalcoholic fatty liver disease (NAFLD) and vitamin D3 deficiency are two highly prevalent pathologic conditions worldwide that share several cardiometabolic risk factors. In addition to its traditional calcium-related effects on the skeleton, vitamin D3 deficiency has now been recognized to exert nonskeletal adverse effects on several other organ systems. Accumulating epidemiological evidence suggests that low levels of serum 25-hydroxyvitamin D3 are associated with the presence and severity of NAFLD, independently of several potential confounders, including features of the metabolic syndrome. The molecular mechanisms of this association remain incompletely understood. A variety of biologically plausible mechanisms may mediate a hepato-protective role for the active metabolite of vitamin D3. 1α,25-dihydroxyvitamin D3 modulates the insulin signaling pathway/insulin resistance, suppresses fibroblast proliferation and collagen production, exerts anticoagulant and profibrinolytic effects, and modulates macrophage activity and inflammatory cytokine generation. Overall, the high prevalence of vitamin D3 deficiency and the plausible biological mechanisms linking this to NAFLD suggest that treatment of vitamin D3 deficiency to prevent and/or treat NAFLD is a promising field to explore. Large placebo-controlled randomized clinical trials are urgently needed to determine whether vitamin D3 supplementation could have any potential benefit in reducing the development and progression of NAFLD

Therapeutic inflammatory monocyte modulation using immune-modifying microparticles

Inflammatory monocyte-derived effector cells play an important role in the pathogenesis of numerous inflammatory diseases. However, no treatment option exists that is capable of modulating these cells specifically. We show that infused negatively charged, immune-modifying microparticles (IMPs), derived from polystyrene, microdiamonds, or biodegradable poly(lactic-co-glycolic) acid, were taken up by inflammatory monocytes, in an opsonin-independent fashion, via the macrophage receptor with collagenous structure (MARCO). Subsequently, these monocytes no longer trafficked to sites of inflammation; rather, IMP infusion caused their sequestration in the spleen through apoptotic cell clearance mechanisms and, ultimately, caspase-3-mediated apoptosis. Administration of IMPs in mouse models of myocardial infarction, experimental autoimmune encephalomyelitis, dextran sodium sulfate-induced colitis, thioglycollate- induced peritonitis, and lethal flavivirus encephalitis markedly reduced monocyte accumulation at inflammatory foci, reduced disease symptoms, and promoted tissue repair. Together, these data highlight the intricate interplay between scavenger receptors, the spleen, and inflammatory monocyte function and support the translation of IMPs for therapeutic use in diseases caused or potentiated by inflammatory monocytes.15 page(s