Dynamics of concurrent and sequential Central European and Scandinavian heatwaves

In both 2003 and 2018 a heatwave in Scandinavia in July was followed by a heatwave in Central Europe in August. Whereas the transition occurred abruptly in 2003, it was gradual in 2018 with a 12-day period of concurrent heatwaves in both regions. This study contrasts these two events in the context of a heatwave climatology to elucidate the dynamics of both concurrent and sequential heatwaves. Central European and, in particular, concurrent heatwaves are climatologically associated with weak pressure gradient (WPG) events over Central Europe, which indicate the absence of synoptic activity over this region. One synoptic pattern associated with such events is Scandinavian blocking. This pattern is at the same time conducive to heatwaves in Scandinavia, thereby providing a mechanism by which Scandinavian and Central European heatwaves can co-occur. Further, the association of WPG events with Scandinavian blocking constitutes a mechanism that allows heatwaves to grow beyond the perimeter of the synoptic system from which they emanated. A trajectory analysis of the source regions of the low-level air incorporated in the heatwaves indicates rapidly changing air mass sources throughout the heatwaves in both regions, but no recycling of heat from one heatwave to the other. This finding is line with a composite analysis indicating that transitions between Scandinavian and Central European heatwaves are merely a random coincidence of heatwave onset and decay

The mysterious long-range transport of giant mineral dust particles

Giant mineral dust particles (>75 mm in diameter) found far from their source have long puzzled scientists. These wind-blown particles affect the atmosphere’s radiation balance, clouds, and the ocean carbon cycle but are generally ignored in models. Here, we report new observations of individual giant Saharan dust particles of up to 450 mm in diameter sampled in air over the Atlantic Ocean at 2400 and 3500 km from the west African coast. Past research points to fast horizontal transport, turbulence, uplift in convective systems, and electrical levitation of particles as possible explanations for this fascinating phenomenon. We present a critical assessment of these mechanisms and propose several lines of research we deem promising to further advance our understanding and modeling

Interferon β-1a in relapsing multiple sclerosis: four-year extension of the European IFNβ-1a Dose-C omparison Study

Background: Multiple sclerosis (MS) is a chronic disease requiring long-term monitoring of treatment. Objective: To assess the four-year clinical efficacy of intramuscular (IM) IFNb-1a in patients with relapsing MS from the European IFNb-1a Dose-C omparison Study. Methods: Patients who completed 36 months of treatment (Part 1) of the European IFNb-1a Dose-C omparison Study were given the option to continue double-blind treatment with IFNb-1a 30 mcg or 60 mcg IM once weekly (Part 2). Analyses of 48-month data were performed on sustained disability progression, relapses, and neutralizing antibody (NA b) formation. Results: O f 608/802 subjects who completed 36 months of treatment, 493 subjects continued treatment and 446 completed 48 months of treatment and follow-up. IFNb-1a 30 mcg and 60 mcg IM once weekly were equally effective for up to 48 months. There were no significant differences between doses over 48 months on any of the clinical endpoints, including rate of disability progression, cumulative percentage of patients who progressed (48 and 43, respectively), and annual relapse rates; relapses tended to decrease over 48 months. The incidence of patients who were positive for NAbs at any time during the study was low in both treatment groups. Conclusion: C ompared with 60-mcg IM IFNb-1a once weekly, a dose of 30 mcg IM IFNb-1a once weekly maintains the same clinical efficacy over four years

A Lagrangian analysis of upper-tropospheric anticyclones associated with heat waves in Europe

This study presents a Lagrangian analysis of upper-tropospheric anticyclones that are connected to surface heat waves in different European regions for the period 1979 to 2016. In order to elucidate the formation of these anticyclones and the role of diabatic processes, we trace air parcels backwards from the upper-tropospheric anticyclones and quantify the diabatic heating in these air parcels. Around 25&thinsp;%–45&thinsp;% of the air parcels are diabatically heated during the last 3&thinsp;d prior to their arrival in the upper-tropospheric anticyclones, and this amount increases to 35&thinsp;%–50&thinsp;% for the last 7&thinsp;d. The influence of diabatic heating is larger for heat-wave-related anticyclones in northern Europe and western Russia and smaller in southern Europe. Interestingly, the diabatic heating occurs in two geographically separated air streams; 3&thinsp;d prior to arrival, one heating branch (remote branch) is located above the western North Atlantic, and the other heating branch (nearby branch) is located over northwestern Africa and Europe to the southwest of the target upper-tropospheric anticyclone. The diabatic heating in the remote branch is related to warm conveyor belts in North Atlantic cyclones upstream of the evolving upper-level ridge. In contrast, the nearby branch is diabatically heated by convection, as indicated by elevated mixed-layer convective available potential energy along the western side of the matured upper-level ridge. Most European regions are influenced by both branches, whereas western Russia is predominantly affected by the nearby branch. The remote branch predominantly affects the formation of the upper-tropospheric anticyclone, and therefore of the heat wave, whereas the nearby branch is more active during its maintenance. For long-lasting heat waves, the remote branch regenerates. The results from this study show that the dynamical processes leading to heat waves may be sensitive to small-scale microphysical and convective processes, whose accurate representation in models is thus supposed to be crucial for heat wave predictions on weather and climate timescales.</p

Determination of residual stress with high spatial resolution at TSVs for 3D integration: Comparison between HR-XRD, Raman spectroscopy and fibDAC

Three different experimental methods have been used to determine mechanical stresses in silicon nearby tungsten TSVs - HR-XRD performed at a synchrotron beamline, microRaman spectroscopy and stress relief techniques put into effect by FIB ion milling. All methods possess, to a different extend, high spatial resolution capabilities. However they differ in their sensitivity and response to the particular stress tensor components relevant for the residual stress state nearby TSV structures. Stress measurements were performed on test samples with TSVs in thinned dies, which were SLID bonded to a thicker Si substrate die. The measurements captured stresses introduced by the W-TSV as well as by the wafer bonding process. A stress range from several MPa to hundreds of MPa could have been covered with a spatial allocation ranging from 100 nm to tens of microns. Measurement results were compared to each other and to simulated stresses from finite element analysis

Residual stress investigations at TSVs in 3D micro structures by HR-XRD, Raman spectroscopy and fibDAC

In this paper the residual stress in single-crystalline Si around W-filled TSVs was determined experimentally by three methods with high spatial resolution and compared to one another. In contrast to Cu as TSV filler, W has the potential advantage of a lower CTE mismatch to Si resulting in lower thermally induced stress at the TSV-interface. As test layout a cross-sectioned double-die stack was used consisting of a top die with TSVs which is bonded by Cu-Sn Solid Liquid Interdiffusion Bonding (SLID) to the bottom die. Three different experimental methods have been used to determine mechanical stresses in silicon nearby tungsten TSVs - HR-XRD performed at a synchrotron beamline, microRaman spectroscopy and stress relief techniques put into effect by FIB milling. All methods possess, to a different extend, high spatial resolution capabilities. However they differ in their sensitivity and response to the particular stress tensor components relevant for the residual stress state nearby TSV structures. Stress measurements were performed on test samples with W-TSVs in thinned dies, which were SLID bonded to a thicker Si substrate die. The measurements captured stresses introduced by the W-TSV as well as by the wafer bonding process. A stress range from several MPa to hundreds of MPa could have been covered with a spatial resolution ranging from 100 nm to tens of microns. Measurement results were compared to one another and to simulated stresses from finite element analysis (FEA). All experimental methods show the influence of W and Cu-Sn-Bond in Si. The very high stress sensitivity for HR-XRD below 1 MPa could be shown. For small stress gradients the analysis of the peak position gives reasonable results and for larger stress gradients a profile analysis of the diffraction peak is more accurate. The results show that in intrinsic stress in W may have to be considered in FEA and more attention should be directed to the accuracy of the FE-modelled Cu-Sn SLID bond with resp- ct to shrinkage during phase formation of Cu3Sn

Double-blind randomized multicenter dose-comparison study of interferon-beta-1a (AVONEX):rationale, design and baseline data

We describe the rationale and design of a double-blind, randomized multicenter, dose-comparison study of interferon-beta-Ia (IFN-beta -Ia: AVONEX(R) in the treatment of relapsing multiple sclerosis (MS). The study is expected to provide quantitative insights on the dose range for optimal clinical benefits in MS. The study involves 802 patients in 10 European countries who have EDSS scores 2.0-5.5, and who have experienced at least two relapses within the 3 years prior to enrolment Patients ore randomized to receive once-weekly intramuscular injections of IFN-beta -Ia 30 or 60 mcg for at least 3 years. The primary endpoint of the study is the effect of IFN-beta -Ia therapy on the time to sustained progression of disability. For patients with a baseline EDSS less than or equal to 4.5, sustained progression of disability is defined as a I point increase in EDSS from baseline, maintained for 6 months. For patients with baseline EDSS less than or equal to 5, sustained progression of disability is defined as reaching on EDSS greater than or equal to 6.0 maintained for 6 months. EDSS scores will be determined every 3 months. A series of prospectively defined secondary and tertiary efficacy endpoints will be examined Safety will be monitored throughout the study. Magnetic resonance imaging (MRI) with and without gadolinium-enhancement has been Performed in at least 358 patients at baseline and repeated annually after enrolment In a subset of these patients, a frequent MRI study is also being performed