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Envisaging antiferromagnetic spintronics pivots on two key criteria of high transition temperature and tuning of underlying magnetic order using straightforward application of magnetic field or electric current. Here, we show that NiSi metal can provide suitable new platform in this quest. First, our study unveils high temperature antiferromagnetism in single crystal NiSi with $T_{N} \geq 700$ K. Antiferromagnetic order in NiSi is accompanied by the non-centrosymmetric magnetic character with small ferromagnetic component in a-c plane. Second, we find that NiSi manifests distinct magnetic and electronic hysteresis responses to field applications due to the disparity in two moment directions. While magnetic hysteresis is characterized by one-step switching between ferromagnetic states of uncompensated moment, electronic behavior is ascribed to metamagnetic switching phenomena between non-collinear spin configurations. Importantly, the switching behaviors persist to high temperature. The properties underscore the importance of NiSi in the pursuit of antiferromagnetic spintronics., Comment: 8 pages, 6 figures

We demonstrate that supergravity models containing the Standard Model, dilaton and modulus naturally lead to dynamical symmetry breaking with excellent phenomenology. We assume primordial supersymmetry breaking in the form of a constant contribution to the superpotential. String inspired relations link fundamental couplings to the dilaton vev. We specialize to a class of models inspired by the $4$-$D$ fermionic string. Non-renormalizable terms in the superpotential naturally produce the Higgs mixing parameter $\mu$ suitable for our mechanism. We discuss extensions and limitations of our approach., Comment: 8 page plain TeX file with 3 figures in a tarred, compressed, uuencoded ps file

I derive conservative upper bounds on the supersymmetry breaking parameter $m_{1/2}$ as a function of the strong coupling in the Standard Supersymmetric Model (SSM) using gauge coupling unification. I find that over more than $99\%$ of the parameter space, $\alpha_3>0.120$ implies that $m_{1/2}$ is below $10\TeV$ and $\alpha_3>0.129$ implies that $m_{1/2}$ is below $1\TeV$. I express the variation of these bounds over the SSM parameter space with a numerical coefficient, $c$. I also find that in the SSM, a reasonable value of $50\GeV0.119$ over the whole parameter space. These bounds are particularly sensitive to the value of $\sin^2\theta_W=0.2317\pm0.0005$ used in the calculation. In more realistic models, heavy thresholds and gravitational effects will modify this result. Although these effects are theoretically calculable in specific models, more realistic models contain many unknown parameters in practice. I illustrate this point with minimal supersymmetric $SU(5)$ where the combined constraints of gauge coupling unification and proton decay require $\alpha_3>0.119$ for $m_{1/2}<1\TeV$ and the upper bound on the supersymmetry breaking scale is greatly relaxed., Comment: 8 pages (2 figures not included, available upon request)

We revisit the no-scale mechanism in the context of the simplest no-scale supergravity extension of the Standard Model. This model has the usual five-dimensional parameter space plus an additional parameter $\xi_{3/2}\equiv m_{3/2}/m_{1/2}$. We show how predictions of the model may be extracted over the whole parameter space. A necessary condition for the potential to be stable is ${\rm Str}{\cal M}^4>0$, which is satisfied if $\bf m_{3/2}\lsim2 m_{\tilde q}$. Order of magnitude calculations reveal a no-lose theorem guaranteeing interesting and potentially observable new phenomena in the neutral scalar sector of the theory which would constitute a ``smoking gun'' of the no-scale mechanism. This new phenomenology is model-independent and divides into three scenarios, depending on the ratio of the weak scale to the vev at the minimum of the no-scale direction. We also calculate the residual vacuum energy at the unification scale ($C_0\, m^4_{3/2}$), and find that in typical models one must require $C_0>10$. Such constraints should be important in the search for the correct string no-scale supergravity model. We also show how specific classes of string models fit within this framework., Comment: 11pages, LaTeX, 1 figure (included), CERN-TH.7433/94

We derive a one-loop expression, including all thresholds, for the mass of the proton decay mediating color triplets, $M_{D^c}$, in minimal supersymmetric SU(5). The result for $M_{D^c}$ does not depend on other heavy thresholds or extra representations with SU(5) invariant masses which might be added to the minimal model. We numerically correct our result to two-loop accuracy. Choosing inputs to maximize $M_{D^c}$ and $\tau_P$, within experimental limits on the inputs and a $1~TeV$ naturalness bound, we derive a strict bound $\alpha_3>0.117$. We discuss how this bound will change as experimental limits improve. Measurements of $\alpha_3$ from deep inelastic scattering and the charmonium spectrum are below the bound $\alpha_3>0.117$ by more than $3\sigma$. We briefly review several ideas of how to resolve the discrepancy between these low values of $\alpha_3$ and the determinations of $\alpha_3$ from LEP event shapes., Comment: 10 pages (2 figures not included, available upon request), MIU-THP-94/68

I define the Standard Supersymmetric Model (SSM) as the minimal supersymmetric extension ofthe Standard Model with gauge coupling unification and universal soft supersymmetry breaking at the unification scale. This well-defined model has a five-dimensional space of unknown parameters ($m_t, \tan\beta, m_{1/2}, m_0, A$). I outline the top-down and bottom-up methods of solving this model. Thresholds may be treated either by dropping heavy particles from the RGE's or by considering loop corrections to the vacuum energy. Substantial regions of the parameter space are consistent with all experimental constraints. I consider the relation of the SSM to more realistic models such as supersymmetric $SU(5)$, Flipped $SU(5)\times U(1)$, the String-Inspired Standard Model, and string-derived models. I briefly discuss sparticle spectroscopy and flavor changing neutral currents (FCNC's) as sample methods for determining the unknown parameters of the SSM, and discriminating between the SSM and more realistic models., Comment: 25 pages, MIU-THP-93/65

We present the most general supersymmetric amplitude for \kkb\/ and \bbb\/ mixing resulting from gluino box diagrams. We use this amplitude to place general constraints on the magnitude of flavor-changing squark mass mixings, and compare these constraints to theoretical predictions both in and beyond the Minimal Supersymmetric Standard Model., Comment: 11 pages plus 2 figures available on request, MIU-THP-92/60

We review the theoretical and experimental status of minimal grand unified theories (GUTS), contrasting the failure of minimal non-supersymmetric $SU(5)$ with the success of the minimal supersymmetric $SU(5)$ and minimal supersymmetric Flipped $SU(5)\times U(1)$ models. We show that a reasonable value for the universal soft supersymmetry-breaking gaugino mass, $45\GeV.114$. We define the supersymmetric standard model (SSM), the minimal supersymmetric extension of the standard model with gauge coupling unification and universal soft supersymmetry-breaking at the unification scale, as a baseline model for unified theories. We review the structure of the allowed parameter space of the SSM and suggest sparticle spectroscopy as the experimental means to determine the parameters of the SSM and search for departures from the baseline SSM., Comment: 19 pages plus 5 figures available on request, MIU-THP-92/61

We investigate the prospects for neutralino dark matter within the Supersymmetric Standard Model (SSM) including the constraints from universal soft supersymmetry breaking and radiative breaking of the electroweak symmetry. The latter is enforced by using the one-loop Higgs effective potential which automatically gives the one-loop corrected Higgs boson masses. We perform an exhaustive search of the allowed five-dimensional parameter space and find that the neutralino relic abundance $\Omega_\chi h^2_0$ depends most strongly on the ratio $\xi_0\equiv m_0/m_{1/2}$. For $\xi_0\gg1$ the relic abundance is almost always much too large, whereas for $\xi_0\ll1$ the opposite occurs. For $\xi_0\sim1$ there are wide ranges of the remaining parameters for which $\Omega_\chi\sim1$. We also determine that $m_{\tilde q}\gsim250\GeV$ and $m_{\tilde l}\gsim100\GeV$ are necessary in order to possibly achieve $\Omega_\chi\sim1$. These lower bounds are much weaker than the corresponding ones derived previously when radiative breaking was {\it not} enforced., Comment: 12 pages plus 6 figures (not included), CERN-TH.6584/92, CTP-TAMU-56/92, UAHEP9212

We discuss several aspects of state-of-the-art calculations of radiative electroweak symmetry breaking in supergravity models. These models have a five-dimensional parameter space in contrast with the 21-dimensional one of the MSSM. We examine the Higgs one-loop effective potential $V_1=V_0+\Delta V$, in particular how its renormalization-scale ($Q$) independence is affected by the approximations used to calculate $\Delta V$ and by the presence of a Higgs-field-independent term which makes $V_1(0)\not=0$. We show that the latter must be subtracted out to achieve $Q$-independence. We also discuss our own approach to the exploration of the five-dimensional parameter space and the fine-tuning constraints within this approach. We apply our methods to the determination of the allowed region in parameter space of two models which we argue to be the prototypes for conventional (SSM) and string (SISM) unified models. To this end we impose the electroweak breaking constraint by minimizing the one-loop effective potential and study the shifts in $\mu$ and $B$ relative to the values obtained using the tree-level potential. These shifts are most significant for small values of $\mu$ and $B$, and induce corresponding shifts on the lightest $\mu$- and/or $B$-dependent particle masses, \ie, those of the lightest stau, neutralino, chargino, and Higgs boson states. Finally, we discuss the predictions for the squark, slepton, and one-loop corrected Higgs boson masses., Comment: 48 pages plus 17 figures (not included but available); CERN-TH.6498/92, CTP-TAMU-16/92

We reanalyze precision LEP data and coupling constant unification in the minimal supersymmetric $SU(5)$ model including the evolution of the gaugino masses. We derive general bounds on the primordial gaugino supersymmetry-breaking mass-scale $m_{1/2}$ in terms of the various input parameters. The model cannot accommodate $m_{1/2}<1\TeV$ for values of $\as < 0.115$, even for extreme $1-\sigma$ values of the other inputs. We emphasize the sensitivity of this type of calculations to the various input parameters., Comment: 9 pages, 1 figure not included, ACT-10/92

The Apollo virtual microscope is a means of viewing, over the Internet, polished thin sections of every rock in the Apollo lunar sample collections. It uses software that duplicates many of the functions of a petrological microscope.

This document contains five working papers featuring employment projections for five segments of industry in Ohio. The purpose of the studies described in the papers is to evaluate projections generated by the quantitative models used in the projections process and to elicit insights and qualitative information from industry practitioners that are not otherwise available to analysts. The methodology for these projections involves a projection of Ohio's share of national industry employment for each industrial sector. This share projection is then fitted to the Bureau of Labor Statistics' projection for each industry to estimate Ohio's employment in the sector in the target year. These sectoral employment projections are then fitted to industry-specific staffing patterns derived from periodic surveys of Ohio business establishments adjusted by a set of change factors to anticipate the effects of technical change on the occupational mix. These final estimates of future occupational requirements are then adjusted by a set of occupation-specific replacement rates to estimate total requirements. The more qualitative analysis represented by the working papers reflects a concern with the validity of long-term projection models in periods and in areas affected by extreme structural change and/or severe economic fluctuations. The employment projections in these five papers are for the primary metals industry; fabricated metal products; machinery industry (except electrical); electrical and electronic machinery, equipment, and supplies; and transportation equipment. The package also includes a report on a test of the Occupational Area-specific Staffing Information System (OASIS). (KC)

We model the fluids involved in the alteration processes recorded in the Sheep bed Member mudstones of Yellowknife Bay (YKB), Gale crater, Mars, as revealed by the Mars Science Laboratory Curiosity rover investigations. We compare the Gale crater waters with fluids modeled for shergottites, nakhlites, and the ancient meteorite ALH 84001, as well as rocks analyzed by the Mars Exploration rovers, and with terrestrial ground and surface waters. The aqueous solution present during sediment alteration associated with phyllosilicate formation at Gale was high in Na, K, and Si; had low Mg, Fe, and Al concentrations relative to terrestrial ground waters such as the Deccan Traps and other modeled Mars fluids; and had near neutral to alkaline pH. Ca and S species were present in the 10(exp -3) to 10(exp -2) concentration range. A fluid local to Gale crater strata produced the alteration products observed by Curiosity and subsequent evaporation of this ground water- type fluid formed impure sulfate- and silica-rich deposits veins or horizons. In a second, separate stage of alteration, partial dissolution of this sulfate-rich layer in Yellowknife Bay,or beyond, led to the pure sulfate veins observed in YKB. This scenario is analogous to similar processes identified at a terrestrial site in Triassic sediments with gypsum veins of the Mercia Mudstone Group in Watchet Bay, UK.

Yellowknife Bay (YKB; sol 124-198) is the second site that the Mars Science Laboratory Rover Curiosity investigated in detail on its mission in Gale Crater. YKB represents lake bed sediments from an overall neutral pH, low salinity environment, with a mineralogical composition which includes Ca-sulfates, Fe oxide/hydroxides, Fe-sulfides, amorphous material, and trioctahedral phyllosilicates. We investigate whether sulfide alteration could be associated with ancient habitable microenvironments in the Gale mudstones. Some textural evidence for such alteration may be pre-sent in the nodules present in the mudstone.

The Apollo virtual microscope is a means of viewing, over the Internet, polished thin sections of every rock in the Apollo lunar sample collections via software, duplicating many of the functions of a petrological microscope, is described. Images from the Apollo 11 and 12 missions may be viewed at: www.virtualmicroscope.org/content/apollo. Introduction: During the six NASA missions to the Moon from 1969-72 a total of 382 kilograms of rocks and soils, often referred to as "the legacy of Apollo", were collected and returned to Earth. A unique collection of polished thin sections (PTSs) was made from over 400 rocks by the Lunar Sample Curatorial Facility at the Johnson Spacecraft Center (JSC), Houston. These materials have been available for loan to approved PIs but of course they can't be simultaneously investigated by several researchers unless they are co-located or the sample is passed back and forward between them by mail/hand carrying which is inefficient and very risky for irreplaceable material. When The Open University (OU), the world's largest Distance Learning Higher Education Establishment found itself facing a comparable problem (how to supply thousands of undergraduate students with an interactive petrological microscope and a personal set of thin sections), it decided to develop a software tool called the Virtual Microscope (VM). As a result it is now able to make the unique and precious collection of Apollo specimens universally available as a resource for concurrent study by anybody in the world's Earth and Planetary Sciences community. Herein, we describe the first steps of a collaborative project between OU and the Johnson Space Center (JSC) Curatorial Facility to record a PTS for every lunar rock, beginning with those collected by the Apollo 11 and 12 missions. Method: Production of a virtual microscope dedicated to a particular theme divides into four main parts - photography, image processing, building and assembly of virtual microscope components, and publication on a website. Two large research quality microscopes are used to collect all the images required for a virtual microscope. The first is part of an integrated package that utilizes Leica PowerMosaic software and a motorised XYZ stage to generate large area mosaics. It includes a fast acquisition camera and depending on the PTS size normally is used to produce seamless mosaic images consisting of 100-500 individual photographs. If the sample is suitable, three mosaics of each sample are recorded - plane polarised light, between crossed polars and reflected light. In order for the VM to be a true petrological microscope it is necessary to recreate the features of a rotating stage and perform observations using filters to produce polarised light. Thus the petrological VM includes the capability of seeing changes in optical properties (pleochroism and birefringence) during rotation allowing mineral identification. The second microscope in the system provides the functions of the rotating stage. To this microscope we have added a robotically controlled motor to acquire seventy-two images (5 degree intervals) in plane polarised light and between crossed polars. To process the images acquired from the two microscopes involves a combination of proprietary software (Photoshop) and our own in-house code. The final stage involves assembling all the components in an HTML5 environment. Pathfinder investigations: We have undertaken a number of pilot studies to demonstrate the efficacy of the petrological microscope with lunar samples. The first was to make available on-line images collected from the Educational Package of Apollo samples provided by NASA to the UK STFC (Science and Technical Facilities Council) for loan as educational material e.g. for schools. The real PTSs of the samples are now no longer sent out to schools removing the risks associated with transport, accidental breakage and eliminating the possibility of loss. The availability of lunar sample VM-related material was further extended to include twenty-eight specimens from all of the Apollo missions. Some of these samples were made more generally available through an ibook entitled "Moon Rocks: an introduction to the Geology of the Moon," free from the Apple Bookstore. Research possibilities: Although the Virtual Microscope was originally conceived as a teaching aid and was later recognised as a means of public outreach and engagement, we now realize that it also has enormous potential as a high level research tool. Following discussions with the JSC Curators we have received Curation and Analysis Planning Team for Extraterrestrial Materials (CAPTEM) permission to embark on a programme of digitizing the entire lunar sample PTS collection for all three of the above purposes. By the time of the 47th Lunar and Planetary Science Conference (LPSC) we will have completed 81 rocks collected during the Apollo 11 and 12 missions and the data, with cross-links to the Lunar Sample Compendium will go live on the Web at the 47th LPSC. The VM images of the Apollo 11 (41 VM images) and 12 (40 VM images) missions can be viewed at: http:/www.virtualmicroscope.org/content/apollo. The lunar sample VM will enable large numbers of skilled/unskilled microscopists (professional and amateur researchers, educators and students, enthusiasts and the simply curious non-scientists) to share the information from a single sample. It will mean that all the PTSs already cut, even historical ones, could be available for new joint investigations or private study. The scientific return from the collection will increase exponentially as a result of further debate and discussion. Simultaneously the VM will remove the need for making unnecessary multiple samplings, avoid consignment of delicate/breakable specimens (all of which are priceless) to insecure mail/courier services and reduce direct labour and indirect costs, travel budgets and unproductive travelling time necessary for co-location of collaborating researchers. For the future we have already recognized further potential for virtual technology. There is nothing that a petrologist likes more than to see the original rock as a hand specimen. It is entirely possible to recreate virtual hand specimens with 3-D hard and software, already developed for viewing fossils, located within the Curatorial Facility, http://curator.jsc.nasa.gov/lunar/lsc/index.cfm.

A means of viewing, over the Internet, polished thin sections of every rock in the Apollo lunar sample collections via software, duplicaing many of the functions of a petrological microscope, is described.

A successful Mars exploration program has revealed chapters of Mars history, but in this book, the pages are ripped out of the binding and scattered across the surface. An examination of each page reveals interesting information, but there is no way to read the book in a logical order. Geochronology is the tool that puts page number onto the individual pages, and allows the book of Martian history to be read in its proper order. The KArLE experiment performs the first dedicated in situ geochronology investigation on Mars, bringing clarity to Mars 2020 samples and context to its landing site.