Monoallelic expression of the var multigene family enables immune evasion of the malaria parasite Plasmodium falciparum in its human host. At a given time only a single member of the 60-member var gene family is expressed at a discrete perinuclear region called the 'var expression site'. However, the mechanism of var gene counting remains ill-defined. We hypothesize that activation factors asso...

Value at risk (VaR) is an important and widely used measure of the extent to which a given portfolio is subject to risk present in nancial markets. Considerable amount of research was dedicated during recent years to development of acceptable methods for evaluation of this risk measure. In this paper, we present a method of calculating the portfolio which gives the optimal VaR among those, whic...

The virulence of Plasmodium falciparum, the causative agent of the deadliest form of human malaria, is attributed to its ability to evade human immunity through antigenic variation. These parasites alternate between expression of variable antigens, encoded by members of a multicopy gene family named var. Immune evasion through antigenic variation depends on tight regulation of var gene expressi...

Value at Risk (VaR) has emerged in recent years as a standard tool to measure and control the risk of trading portfolios. Yet, existing theoretical analyses of the optimal behavior of a trader subject to VaR limits have produced a negative view of VaR as a risk-control tool. In particular, VaR limits have been found to induce increased risk exposure in some states and an increased probability o...

BACKGROUND The variable antigen P. falciparum erythrocyte membrane protein-1 (PfEMP1) is a major virulence factor in malaria. A large number of var genes encode PfEMP1, and we hypothesized that a restricted PfEMP1 repertoire determines clinical disease presentation. We conducted a case-control study in Papua New Guinea and analyzed transcribed var genes in naturally infected children. METHODS...

Exercise [2.1.5] Let > 0 and pick K = K( ) finite such that if k ≥ K then r(k) ≤ . Applying the Cauchy-Schwarz inequality for Xi −EXi and Xj −EXj we have that Cov(Xi, Xj) ≤ [Var(Xi)Var(Xj)] ≤ r(0) <∞ for all i, j. Thus, breaking the double sum in Var(Sn) = ∑n i,j=1 Cov(Xi, Xj) into {(i, j) : |i − j| < K} and {(i, j) : |i− j| ≥ K} gives the bound Var(Sn) ≤ 2Knr(0) + n . Dividing by n we see that...

Value-at-risk (VaR) has become the standard criterion for assessing risk in the financial industry. Given the widespread usage of VaR, it becomes increasingly important to study the effects of VaR-based risk management on the prices of stocks and options. We solve a continuous-time asset pricing model, based on Lucas (1978) and Basak and Shapiro (2001), to investigate these effects. We find tha...

The importance of a gene's natural chromatin environment for its normal expression is poignantly illustrated when a change in chromosome position results in variable gene repression, such as is observed in position effect variegation (PEV) when the Drosophila melanogaster white (omega) gene is juxtaposed with heterochromatin. The Enhancer of variegation 3-9 [E(var)3-9] gene was one of over a hu...

Cowden syndrome (CS), a Mendelian autosomal-dominant disorder, predisposes to breast, thyroid and other cancers. Germline mutations in phosphatase and tensin homolog (PTEN) have been recently reported in 23% of a large series of classic CS. Here, we validated our small (n = 10) pilot study in a large patient series that germline variations in succinate dehydrogenase genes (SDHx) occur in 8% (49...

Exercise [2.1.5] Let > 0 and pick K = K( ) finite such that if k ≥ K then r(k) ≤ . Applying the Cauchy-Schwarz inequality for Xi −EXi and Xj −EXj we have that Cov(Xi, Xj) ≤ [Var(Xi)Var(Xj)] ≤ r(0) <∞ for all i, j. Thus, breaking the double sum in Var(Sn) = ∑n i,j=1 Cov(Xi, Xj) into {(i, j) : |i − j| < K} and {(i, j) : |i− j| ≥ K} gives the bound Var(Sn) ≤ 2Knr(0) + n . Dividing by n we see that...