Cross‐Section Stock Return and Implied Covariance between Jump and Diffusive Volatility

I examine the information content of option‐implied covariance between jumps and diffusive risk in the cross‐sectional variation in future returns. This paper documents that the difference between realized volatility and implied covariance (RV‐ICov) can predict future returns. The results show a significant and negative association of expected return and realized volatility–implied covariance spread in both the portfolio level analysis and cross‐sectional regression study. A trading strategy of buying a portfolio with the lowest RV‐ICov quintile portfolio and selling with the highest one generates positive and significant returns. This RV‐Cov anomaly is robust to controlling for size, book‐to‐market value, liquidity and systematic risk proportion. Copyright © 2015 John Wiley & Sons, Ltd.     

Gastrointestinal helminths of nine species of Cnemaspis (Squamata: Gekkonidae) from Peninsular Malaysia,one species from Cambodia and Thailand and two species from Vietnam

A total of 12 species of Cnemaspis (N = 104) from Southeast Asia were examined for gastrointestinal helminths. Samples consisted of nine species (n = 86) from Peninsular Malaysia: Cnemaspis affinis (n = 4); Cnemaspis baueri (n = 17); Cnemaspis biocellata (n = 12); Cnemaspis grismeri (n = 8); Cnemaspis kumpoli (n = 11); Cnemaspis limi (n = 9): Cnemaspis monachorum (n = 7); Cnemaspis pemanggilensis (n = 10); Cnemaspis peninsularis (n = 8); one species (n = 5) from Cambodia and Thailand, Cnemaspis chanthaburiensis (n = 5); and two species (n = 13) from Vietnam: Cnemaspis nuicamensis (n = 6) and Cnemaspis tucdupensis (n = 7). The aggregate helminth community consisted of one species of Cestoda, Cylindrotaenia malayi and nine species of Nematoda: Bakeria schadi, Meteterakis singaporensis, Parapharyngodon maplestoni, Maxvachonia sp., Physalopteroides sp., Physalopteridae gen. sp., Riticulariidae gen. sp., Seuratoidea gen. sp., Ascaridoidea gen. sp. Meteterakis singaporensis had the largest number of individuals (457) and greatest prevalence (24%). Twenty-eight new host records are reported.     

Requirements for leukocyte transmigration via the transmembrane chemokine CX3CL1

The surface-expressed transmembrane CX3C chemokine ligand 1 (CX3CL1/fractalkine) induces firm adhesion of leukocytes expressing its receptor CX3CR1. After shedding by the disintegrins and metalloproteinases (ADAM) 10 and 17, CX3CL1 also acts as soluble leukocyte chemoattractant. Here, we demonstrate that transmembrane CX3CL1 expressed on both endothelial and epithelial cells induces leukocyte transmigration. To investigate the underlying mechanism, we generated CX3CR1 variants lacking the intracellular aspartate-arginine-tyrosine (DRY) motif or the intracellular C-terminus which led to a defect in intracellular calcium response and impaired ligand uptake, respectively. While both variants effectively mediated firm cell adhesion, they failed to induce transmigration and rather mediated retention of leukocytes on the CX3CL1-expressing cell layer. Targeting of ADAM10 led to increased adhesion but reduced transmigration in response to transmembrane CX3CL1, while transmigration towards soluble CX3CL1 was not affected. Thus, transmembrane CX3CL1 mediates leukocyte transmigration via the DRY motif and C-terminus of CX3CR1 and the activity of ADAM10.     

Yersinia pestis genome sequencing identifies patterns of global phylogenetic diversity

Plague is a pandemic human invasive disease caused by the bacterial agent Yersinia pestis. We here report a comparison of 17 whole genomes of Y. pestis isolates from global sources. We also screened a global collection of 286 Y. pestis isolates for 933 SNPs using Sequenom MassArray SNP typing. We conducted phylogenetic analyses on this sequence variation dataset, assigned isolates to populations based on maximum parsimony and, from these results, made inferences regarding historical transmission routes. Our phylogenetic analysis suggests that Y. pestis evolved in or near China and spread through multiple radiations to Europe, South America, Africa and Southeast Asia, leading to country-specific lineages that can be traced by lineage-specific SNPs. All 626 current isolates from the United States reflect one radiation, and 82 isolates from Madagascar represent a second radiation. Subsequent local microevolution of Y. pestis is marked by sequential, geographically specific SNPs.     

Triosephosphate isomerase: a highly evolved biocatalyst

Triosephosphate isomerase (TIM) is a perfectly evolved enzyme which very fast interconverts dihydroxyacetone phosphate and d-glyceraldehyde-3-phosphate. Its catalytic site is at the dimer interface, but the four catalytic residues, Asn11, Lys13, His95 and Glu167, are from the same subunit. Glu167 is the catalytic base. An important feature of the TIM active site is the concerted closure of loop-6 and loop-7 on ligand binding, shielding the catalytic site from bulk solvent. The buried active site stabilises the enediolate intermediate. The catalytic residue Glu167 is at the beginning of loop-6. On closure of loop-6, the Glu167 carboxylate moiety moves approximately 2 Å to the substrate. The dynamic properties of the Glu167 side chain in the enzyme substrate complex are a key feature of the proton shuttling mechanism. Two proton shuttling mechanisms, the classical and the criss-cross mechanism, are responsible for the interconversion of the substrates of this enolising enzyme.     

Book Review: Current Perspectives in the History of Science in East Asia,edited by Y. S. Kim and F. Bray

In 1670, the Bolognese mathematician Pietro Mengoli published his Speculationi di musica, a highly original work attempting to found the mathematical study of music on the anatomy of the ear. His anatomy was idiosyncratic and his mathematics extraordinarily complex, and he proposed a unique double mechanism of hearing. He analysed in detail the supposed behaviour of the subtle part of the air inside the ear, and the patterns of strokes made on the eardrum by simultaneous sounds. Most strikingly, he divided the musical octave into a continuous set of regions which he colour-coded to show their effects on a listener. His work did not find its way into the mainstream of seventeenth-century mathematical studies of music, but when examined in its context it has the potential to shed light on that discipline, as well as being of considerable interest in its own right. Here, I focus on the anatomical and mathematical basis of Mengoli's work.