Domain State Model for Exchange Bias

Monte Carlo simulations of a system consisting of a ferromagnetic layer exchange coupled to a diluted antiferromagnetic layer described by a classical spin model show a strong dependence of the exchange bias on the degree of dilution in agreement with recent experimental observations on Co/CoO bilayers. These simulations reveal that diluting the antiferromagnet leads to the formation of domains in the volume of the antiferromagnet carrying a remanent surplus magnetization which causes and controls exchange bias. To further support this domain state model for exchange bias we study in the present paper the dependence of the bias field on the thickness of the antiferromagnetic layer. It is shown that the bias field strongly increases with increasing film thickness and eventually goes over a maximum before it levels out for large thicknesses. These findings are in full agreement with experiments.Comment: 8 pages latex, 3 postscript figure

Exchange Rate Fundamentals and Order Flow (July 2004)

This paper addresses the striking ability of transaction flows to explain exchange rate movements. Specifically, we examine whether this arises because transaction flows convey incremental information about fundamentals. If so, then these flows should affect price upon their realization and observation by price setters (marketmakers). Our model is a simple general equilibrium model of information aggregation that provides---in a setting of incomplete markets---a utility-based present-value representation for exchange rates. The model produces testable implications for the relationships between realized transaction flows, current and future exchange rate returns, and future fundamentals (e.g., money supplies). We then bring these implications to the data, making use of a new dataset covering over six years of transactions (which permits estimation at the monthly frequency). We find strong contemporanous effects of transaction flows on exchange rates, corroborating past findings. More importantly, we present four key findings that are both new to the literature and supportive of our model: (1) transaction flows forecast (Granger cause) future macroeconomic variables such as money growth, output growth, and inflation, (2) transaction flows forecast future exchange rates changes, and do so more effectively than forward discounts, (3) the future exchange rate components that current flows forecast are primarily the future non-flow-driven components, and (4) though flows convey new information about future fundamentals, much of this information is still not impounded in the exchange rate 9 months later. The slow pace of learning implies that abstracting from information aggregation---as is standard in exchange rate economics---is not innocuous.Exchange Rate Dynamics, Microstructure, Order Flow.

How is Macro News Transmitted to Exchange Rates? (December 2003)

This paper tests whether macroeconomic news is transmitted to exchange rates via the transactions process and if so, what share occurs via transactions versus the traditional direct channel. We identify the link between order flow and macro news using a heteroskedasticity-based approach, a la Rigobon and Sack (2002). In both daily and intra-daily data, order flow varies considerably with macro news flow. At least half of the effect of macro news on exchange rates is transmitted via order flow.

Meese-Rogoff Redux: Micro-Based Exchange Rate Forecasting

This paper compares the true, ex-ante forecasting performance of a micro-based model against both a standard macro model and a random walk. In contrast to existing literature, which is focused on longer horizon forecasting, we examine forecasting over horizons from one day to one month (the one-month horizon being where micro and macro analysis begin to overlap). Over our 3-year forecasting sample, we find that the micro-based model consistently out-performs both the random walk and the macro model. Micro-based forecasts account for almost 16 per cent of the sample variance in monthly spot rate changes. These results provide a level of empirical validation as yet unattained by other models. Though our micro-based model out-performs the macro model, this does not imply that past macro analysis has overlooked key fundamentals: our structural interpretation using a fundamentals-based model shows that our findings are consistent with exchange rates being driven by standard fundamentals.Exchange rates, forecasting, Meese and Rogoff, microstructure, order flow

Interleukin-1?, Interleukin-6, and Antagonist Interleukin-1receptor as Memory Impairment Risk Factor in Complex Partial Epilepsy

Memory impairment is one of the most common adverse following epilepsy, particularly complex partial epilepsy. Cytokines physiologically play an important role in memory impairment by preventing long term potentiation process in hypocampus. Several literatures have mentioned that IL-1b, IL-6 and antagonist receptor IL-1Ra are crucial cytokines in complex partial epilepsy. This study aims to find out whether high level of IL-1b and IL-6 as well as low level of IL-1Ra might be risk factors of memory impairment in complex partial epilepsy patient. This was a case control study, enrolling 30 complex partial epilepsy patients with memory impairment as case group and 30 complex partial epilepsy patients without memory impairment as control group. In this study, it was obtained that the mean of IL-1? level in case group was significantly higher compared to the control (2.74 ± 4.36 vs. 0.42 ± 0.18 pg/ml, p = 0.007). The mean of IL-6 in case group was significantly higher compare to control (5.89 ± 6.32 vs. 2.34 ± 1.80 pg/ml, p = 0.006). The mean of IL-1Ra level of the case group was not significantly higher compared to the control (519.81 ± 262.64 vs. 413.28 ± 106.85, p = 0.767). By applying bivariate analysis, McNemar's test, we observed that IL-1? with cut off point 0.63 pg/ml and OR = 70 is a risk factor of memory impairment in complex partial epilepsy indicated by p = 0.001. Similar result was also gained for IL-6 with cut off point 2.87 pg/ml and OR = 4.57 as a risk factor of memory impairment in complex partial epilepsy indicated by p = 0.007. Meanwhile, IL- 1Ra with cut off point 471 pg/ml and OR = 0.727 was not as a risk factor of memory impairment in complex partial epilepsy indicated by p = 0.573. It can be concluded that the high level of IL-1B and IL-6 were the risk factors of memory impairment in complex partial epilepsy patients. High level 1L-1B patient was 70 times higher risk of becoming memory impaired. High IL-6 patients will have the risk nearly 5 times higher. The low level of IL-1Ra does not as a risk factor in epilepsy patients for having the following memory impairment

Measurement of the fraction of t-tbar production via gluon-gluon fusion in p-pbar collisions at sqrt(s)=1.96 TeV

We present a measurement of the ratio of t-tbar production cross section via gluon-gluon fusion to the total t-tbar production cross section in p-pbar collisions at sqrt{s}=1.96 TeV at the Tevatron. Using a data sample with an integrated luminosity of 955/pb recorded by the CDF II detector at Fermilab, we select events based on the t-tbar decay to lepton+jets. Using an artificial neural network technique we discriminate between t-tbar events produced via q-qbar annihilation and gluon-gluon fusion, and find Cf=(gg->ttbar)/(pp->ttbar)<0.33 at the 68% confidence level. This result is combined with a previous measurement to obtain the most precise measurement of this quantity, Cf=0.07+0.15-0.07.Comment: submitted to Phys. Rev.

Measurement of Resonance Parameters of Orbitally Excited Narrow B^0 Mesons

We report a measurement of resonance parameters of the orbitally excited (L=1) narrow B^0 mesons in decays to B^{(*)+}\pi^- using 1.7/fb of data collected by the CDF II detector at the Fermilab Tevatron. The mass and width of the B^{*0}_2 state are measured to be m(B^{*0}_2) = 5740.2^{+1.7}_{-1.8}(stat.) ^{+0.9}_{-0.8}(syst.) MeV/c^2 and \Gamma(B^{*0}_2) = 22.7^{+3.8}_{-3.2}(stat.) ^{+3.2}_{-10.2}(syst.) MeV/c^2. The mass difference between the B^{*0}_2 and B^0_1 states is measured to be 14.9^{+2.2}_{-2.5}(stat.) ^{+1.2}_{-1.4}(syst.) MeV/c^2, resulting in a B^0_1 mass of 5725.3^{+1.6}_{-2.2}(stat.) ^{+1.4}_{-1.5}(syst.) MeV/c^2. This is currently the most precise measurement of the masses of these states and the first measurement of the B^{*0}_2 width.Comment: 7 pages, 1 figure, 1 table. Submitted to Phys.Rev.Let

Search for lepton flavor violating decays of a heavy neutral particle in p-pbar collisions at root(s)=1.8 TeV

We report on a search for a high mass, narrow width particle that decays directly to e+mu, e+tau, or mu+tau. We use approximately 110 pb^-1 of data collected with the Collider Detector at Fermilab from 1992 to 1995. No evidence of lepton flavor violating decays is found. Limits are set on the production and decay of sneutrinos with R-parity violating interactions.Comment: Figure 2 fixed. Reference 4 fixed. Minor changes to tex

Classical BI: Its Semantics and Proof Theory

We present Classical BI (CBI), a new addition to the family of bunched logics which originates in O'Hearn and Pym's logic of bunched implications BI. CBI differs from existing bunched logics in that its multiplicative connectives behave classically rather than intuitionistically (including in particular a multiplicative version of classical negation). At the semantic level, CBI-formulas have the normal bunched logic reading as declarative statements about resources, but its resource models necessarily feature more structure than those for other bunched logics; principally, they satisfy the requirement that every resource has a unique dual. At the proof-theoretic level, a very natural formalism for CBI is provided by a display calculus \`a la Belnap, which can be seen as a generalisation of the bunched sequent calculus for BI. In this paper we formulate the aforementioned model theory and proof theory for CBI, and prove some fundamental results about the logic, most notably completeness of the proof theory with respect to the semantics.Comment: 42 pages, 8 figure