Optimizing direct laser-driven electron acceleration and energy gain at ELI-NP

We study and discuss electron acceleration in vacuum interacting with fundamental Gaussian pulses using specific parameters relevant for the multi-PW femtosecond lasers at ELI-NP. Taking into account the characteristic properties of both linearly and circularly polarized Gaussian beams near focus we have calculated the optimal values of beam waist leading to the most energetic electrons for given laser power. The optimal beam waist at full width at half maximum correspond to few tens of wavelengths, $\Delta w_0=\left\{13,23,41\right\}\lambda_0$, for increasing laser power $P_0 = \left\{0.1,1,10\right\}$ PW. Using these optimal values we found an average energy gain of a few MeV and highest-energy electrons of about $160$ MeV in full-pulse interactions and in the GeV range in case of half-pulse interaction.Comment: 12 pages, 10 figure

Transitioning a Project-Based Course between Onsite and Online. An Experience Report

We present an investigation regarding the challenges faced by student teams across four consecutive iterations of a team-focused, project-based course in software engineering. The studied period includes the switch to fully online activities in the spring of 2020, and covers the return to face-to-face teaching two years later. We cover the feedback provided by over 1,500 students, collected in a free-text form on the basis of a survey. A qualitative research method was utilized to discern and examine the challenges and perceived benefits of a course that was conducted entirely online. We show that technical challenges remain a constant in project-based courses, with time management being the most affected by the move to online. Students reported that the effective use of collaborative tools eased team organization and communication while online. We conclude by providing a number of action points regarding the integration of online activities in face-to-face course unfolding related to project management, communication tools, the importance of teamwork, and of active mentor participation.Comment: 12 pages, 2 figure

STB-White

The final design of a hypersonic, SCRAMjet research aircraft, which is to be dropped from a carrier plane, is considered. Topics such as propulsion systems, aerodynamics, component weight analysis, and aircraft design with waverider analyses are stressed with smaller emphasis placed on aircraft systems such as cockpit design and landing gear configurations. Propulsion systems include analysis of the turbofanramjet for acceleration to low hypersonic speed (Mach 6.0) and analysis of the SCRAMjets themselves to carry the aircraft to Mach 10.0. Both analyses include the use of liquid hydrogen as fuel. Inlet design for both propulsion systems is analyzed as well. Aerodynamic properties are found using empirical and theoretical formulas for lift and drag on delta-wing aircraft. The aircraft design involves the integration of all preliminary studies into a modified waverider configuration

A Precise Cluster Mass Profile Averaged from the Highest-Quality Lensing Data

We outline our methods for obtaining high precision mass profiles, combining independent weak-lensing distortion, magnification, and strong-lensing measurements. For massive clusters the strong and weak lensing regimes contribute equal logarithmic coverage of the radial profile. The utility of high-quality data is limited by the cosmic noise from large scale structure along the line of sight. This noise is overcome when stacking clusters, as too are the effects of cluster asphericity and substructure, permitting a stringent test of theoretical models. We derive a mean radial mass profile of four similar mass clusters of high-quality HST and Subaru images, in the range R=40kpc/h to 2800kpc/h, where the inner radial boundary is sufficiently large to avoid smoothing from miscentering effects. The stacked mass profile is detected at 58-sigma significance over the entire radial range, with the contribution from the cosmic noise included. We show that the projected mass profile has a continuously steepening gradient out to beyond the virial radius, in remarkably good agreement with the standard Navarro-Frenk-White form predicted for the family of CDM-dominated halos in gravitational equilibrium. The central slope is constrained to lie in the range, -dln{\rho}/dln{r}=0.89^{+0.27}_{-0.39}. The mean concentration is c_{vir}=7.68^{+0.42}_{-0.40} (at a mean virial mass 1.54^{+0.11}_{-0.10}\times 10^{15} M_{sun}/h), which is high for relaxed, high-mass clusters, but consistent with LCDM when a sizable projection bias estimated from N-body simulations is considered. This possible tension will be more definitively explored with new cluster surveys, such as CLASH, LoCuSS, Subaru HSC, and XXM-XXL, to construct the c-M relation over a wider mass range.Comment: Accepted by ApJ, minor text changes (10 pages, 3 figures

Electron-microscopic study on structural changes of mini-implants following fixed orthodontic treatment

In today's society, patients who turn to the orthodontist want final results in the shortest possible time, with maximum emphasis on smile aesthetics, dental alignment and facial harmony. In this regard, some procedures have emerged to accelerate the movement of teeth through the alveolar bone, thus shortening the duration of active treatment: corticotomy, application of mini-implants, etc. Of these methods, bone anchorage on mini-implants is increasingly popular among adult patients, as it is a versatile technique that ensures a stable, bony anchorage and more predictable final results. Compared to implantology in prosthodontics, which has a long history, mini- orthodontic implants emerged later in medical practice. In 1998, Shapiro and Kokich described for the first time the possibility of using dental implants for anchorage in orthodontic therapy. Odman J et al. (Upsala University, Sweden) applied implants to patients with partial edentulousness. The results were favorable, leading the authors to recommend the technique for adult partial edentulousness. Kanomi (1997) showed that a 1.2 mm diameter titanium mini- implant provides anchorage for the intrusion of the lower front teeth. After 4 months, the mandibular incisors were intruded by 6 mm without root resorption. Birte Melsen et al. (1998) introduced the use of zygomatic ligatures as anchorage in patients with partial edentulousness. To this they attached nickel-titanium springs for intrusion and retraction of maxillary incisors. Hugo de Clerk (2008) used 4 mini-implants (Bollard type) inserted into the infra-zygomatic crest in patients with Angle class III anomalies. He used 2 mini-implants with hooks in the chin area, and patients wore Class III 150 grams elastics on each side. This direct anchorage also has orthopedic effects, with clinicians achieving upper jaw advancement and correction of mandibular prognathism

CLASH: Mass Distribution in and around MACS J1206.2-0847 from a Full Cluster Lensing Analysis

We derive an accurate mass distribution of the galaxy cluster MACS J1206.2-0847 (z=0.439) from a combined weak-lensing distortion, magnification, and strong-lensing analysis of wide-field Subaru BVRIz' imaging and our recent 16-band Hubble Space Telescope observations taken as part of the Cluster Lensing And Supernova survey with Hubble (CLASH) program. We find good agreement in the regions of overlap between several weak and strong lensing mass reconstructions using a wide variety of modeling methods, ensuring consistency. The Subaru data reveal the presence of a surrounding large scale structure with the major axis running approximately north-west south-east (NW-SE), aligned with the cluster and its brightest galaxy shapes, showing elongation with a \sim 2:1 axis ratio in the plane of the sky. Our full-lensing mass profile exhibits a shallow profile slope dln\Sigma/dlnR\sim -1 at cluster outskirts (R>1Mpc/h), whereas the mass distribution excluding the NW-SE excess regions steepens further out, well described by the Navarro-Frenk-White form. Assuming a spherical halo, we obtain a virial mass M_{vir}=(1.1\pm 0.2\pm 0.1)\times 10^{15} M_{sun}/h and a halo concentration c_{vir} = 6.9\pm 1.0\pm 1.2 (\sim 5.7 when the central 50kpc/h is excluded), which falls in the range 4 <7 of average c(M,z) predictions for relaxed clusters from recent Lambda cold dark matter simulations. Our full lensing results are found to be in agreement with X-ray mass measurements where the data overlap, and when combined with Chandra gas mass measurements, yield a cumulative gas mass fraction of 13.7^{+4.5}_{-3.0}% at 0.7Mpc/h (\approx 1.7r_{2500}), a typical value observed for high mass clusters.Comment: Accepted by ApJ (30 pages, 17 figures), one new figure (Figure 10) added, minor text changes; a version with high resolution figures available at http://www.asiaa.sinica.edu.tw/~keiichi/upfiles/MACS1206/ms_highreso.pd