Optical control of magnetization of micron-size domains in antiferromagnetic NiO single crystals

We propose Raman-induced collinear difference-frequency generation (DFG) as a method to manipulate dynamical magnetization. When a fundamental beam propagates along a threefold rotational axis, this coherent second-order optical process is permitted by angular momentum conservation through the rotational analogue of the Umklapp process. As a demonstration, we experimentally obtained polarization properties of collinear magnetic DFG along a [111] axis of a single crystal of antiferromagnetic NiO with micro multidomain structure, which excellently agreed with the theoretical prediction.Comment: 11 pages, 3 figures, submitted to Physical Review Letter

Slow-roll inflation in (R+R*4) gravity

We reconsider the toy-model of topological inflation, based on the R*4-modified gravity. By using its equivalence to the certain scalar-tensor gravity model in four space-time dimensions, we compute the inflaton scalar potential and investigate a possibility of inflation. We confirm the existence of the slow-roll inflation with an exit. However, the model suffers from the eta-problem that gives rise to the unacceptable value of the spectral index n_s of scalar perturbations.Comment: 12 pages, 3 figures, LaTeX, misprints corrected and references update

Observations of the Prompt Gamma-Ray Emission of GRB 070125

The long, bright gamma-ray burst GRB 070125 was localized by the Interplanetary Network. We present light curves of the prompt gamma-ray emission as observed by Konus-WIND, RHESSI, Suzaku-WAM, and \textit{Swift}-BAT. We detail the results of joint spectral fits with Konus and RHESSI data. The burst shows moderate hard-to-soft evolution in its multi-peaked emission over a period of about one minute. The total burst fluence as observed by Konus is $1.79 \times 10^{-4}$ erg/cm$^2$ (20 keV--10 MeV). Using the spectroscopic redshift $z=1.548$, we find that the burst is consistent with the ``Amati'' $E_{peak,i}-E_{iso}$ correlation. Assuming a jet opening angle derived from broadband modeling of the burst afterglow, GRB 070125 is a significant outlier to the ``Ghirlanda'' $E_{peak,i}-E_\gamma$ correlation. Its collimation-corrected energy release $E_\gamma = 2.5 \times 10^{52}$ ergs is the largest yet observed.Comment: 25 pages, 6 figures; accepted for publication in ApJ. Improved spectral fits and energetics estimate

Ohutlevytuotteen välivarastoinnin ja identifioinnin menetelmäkehitystyö

Työssä tutkittiin ohutlevytuotteiden identifioimisen ja välivarastoinnin automatisointia Stofix Montage Teamin toimeksiannosta. Työn tavoitteena oli kehittää menetelmäratkaisut pakattujen ohutlevytuotteiden identifioimiseen ja niiden kuljettamiseen välivarastoon. Stofixilla ohutlevytuotteet identifioidaan ja välivarastoidaan manuaalisesti, mikä sitoo työntekijän samanaikaisesti kahteen eri työvaiheeseen. Tuotteet identifioidaan käyttäen tussikynää ja teippiä ja se on havaittu yrityksessä hitaaksi identifiointimenetelmäksi. Välivarastoidessa pakatut tuotteet nostetaan seinään vasten varastointitilaan, mikä altistaa tuotteet virumiselle ja vaurioitumiselle. Lisäksi tuotteen painon ylittäessä työturvallisuusmääräyksen salliman maksimipainon joutuu työvaiheeseen sitomaan kaksi työntekijää. Ongelmanratkaisuun ja kehitystyöhön käytettiin aikaisempien vuosien robotiikkaa käsitteleviä insinööritöitä sekä automatisoinnin suunnitteluohjekirjoja. Välivarastoinnin ja identifioinnin nykyinen prosessi analysoitiin lähtötilanne-, prosessi- ja kappaleanalyysin pohjalta, jonka kautta menetelmille valittiin komponentteja vertailua varten. Projektin läpiviemiseen käytettiin projektihallinnan aikataulu- ja projekti-suunnitelmapohjia sekä budjettilaskelman muodostavia hintavertailuja tarjouspyynnöistä. Analyysin perusteella menetelmän toteuttamiseen valittiin kattoon sijoitettava lineaarijohteella paikoittava kuusiakselinen robottikäsivarsi ja automaattisesti tulostava tarroituskone. Työn lopputulokseksi tuli robotiikalla ja alipainetarttujalla tehtävä tuotteiden välivarastointi sekä automaattisella tarroituskoneella tapahtuva identifiointi. Työ onnistui odotetusti, ja se tuotti yritykselle robottikäsivarren, alipainetarttujan ja tarroituskoneen komponenttivalinnat budjetoinnin lisäksi. Yritys voi hyödyntää työn tuloksia, kun tuotantoprosessia aletaan automatisoida. Työn jatkokehityskohteena voidaan tehdä robottisolun turvallisuussuunnitelma ja ohjelmointi, lineaarijohteen kompo-nenttivalinnat ja robotin kiinnitysrakenteen mekaniikkasuunnittelu

A molecular structural mechanics model applied to the static behavior of single-walled carbon nanotubes: New general formulation

A new general formulation for the mechanical behavior of Single-Walled Carbon Nanotubes is presented. Carbon atoms are located at the nodes of an hexagonal honeycomb lattice wrapped into a cylinder. They are linked by covalent C C bonds represented by a truss or spring element, and the three-body interaction among two neighboring covalent bonds is reproduced by a rotational spring. The main advantage of our approach is to allow general load conditions (and any chirality) with no need of specific formulation for each load case, in contrast with previous works [26], [27] and [31]. Four load configurations are adopted: tension, compression, bending and torsion of cantivelered SWCNTs. Calculations with our own codes for both AMBER and Morse potential functions have been carried out, aimed to compare their final results. Initial positions of the atoms (nodes) into nanotube cylindrical geometry has been reproduced in great detail by means of a conformal mapping from the planar graphene sheet. Therefore, the effect of initial SWCNTs curvature has been introduced explicitly through a system of initial stresses (prestressed state) which contribute to maintain their circular cross-section. Numerical results and deformed shapes for nanotubes with several diameters and chiralities under each load case are used to obtain their mechanical parameters with the only objective of checking the present formulation with previous works [28], [30], [20] and [24]. Also, the significance of the atomistic discrete simulations at the nano-scale size against other continuum models is underlined.Merli Gisbert, R.; Lazaro, C.; Monleón Cremades, S.; Domingo Cabo, A. (2013). A molecular structural mechanics model applied to the static behavior of single-walled carbon nanotubes: New general formulation. Computers and Structures. 127:68-87. doi:10.1016/j.compstruc.2012.11.023S688712

Divergent Mechanisms Activating RAS and Small GTPases Through Post-translational Modification

RAS is a founding member of the RAS superfamily of GTPases. These small 21 kDa proteins function as molecular switches to initialize signaling cascades involved in various cellular processes, including gene expression, cell growth, and differentiation. RAS is activated by GTP loading and deactivated upon GTP hydrolysis to GDP. Guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs) accelerate GTP loading and hydrolysis, respectively. These accessory proteins play a fundamental role in regulating activities of RAS superfamily small GTPase via a conserved guanine binding (G)-domain, which consists of five G motifs. The Switch regions lie within or proximal to the G2 and G3 motifs, and undergo dynamic conformational changes between the GDP-bound "OFF" state and GTP-bound "ON" state. They play an important role in the recognition of regulatory factors (GEFs and GAPs) and effectors. The G4 and G5 motifs are the focus of the present work and lie outside Switch regions. These motifs are responsible for the recognition of the guanine moiety in GTP and GDP, and contain residues that undergo post-translational modifications that underlie new mechanisms of RAS regulation. Post-translational modification within the G4 and G5 motifs activates RAS by populating the GTP-bound "ON" state, either through enhancement of intrinsic guanine nucleotide exchange or impairing GAP-mediated down-regulation. Here, we provide a comprehensive review of post-translational modifications in the RAS G4 and G5 motifs, and describe the role of these modifications in RAS activation as well as potential applications for cancer therapy

Culinary continuity in central Japan across the transition to agriculture

Rice and millet arrived in Western Japan from Korea around 3,000 years ago and spread eastwards across the archipelago in the next 700 years. However, the extent to which agriculture transformed traditional Jōmon hunter-gatherer-fisher communities is debated. Central Japan is a key area of study as remodelling of radiocarbon dates shows a slowdown in the dispersal rate of rice agriculture in this area. Here, we examine and compare the use of pottery by Final Jōmon and Early to Middle Yayoi communities in the Tōkai and the Central Highland regions of central Japan, using lipid residue analysis. Although the identification of specific biomarkers for rice remains elusive, an increase in the ratio of E/H C18 APAAs with the arrival of rice and millet indicates a potential change in plant processing and consumption. We were also able to identify biomarkers for broomcorn millet (miliacin) in both Final Jōmon and Yayoi pottery. However, evidence for millet consumption is sparse and in all cases was likely mixed with wild hunted and foraged foods. We conclude therefore that, despite the introduction of rice and millet agriculture in central Japan, pre-existing diets and culinary habits of Jōmon hunter-gatherers remain important