Predictability of Equity Models

In this study, we verify the existence of predictability in the Brazilian equity market. Unlike other studies in the same sense, which evaluate original series for each stock, we evaluate synthetic series created on the basis of linear models of stocks. Following the approach of Burgess (Computational Finance, 1999; 99, 297–312), we use the ‘stepwise regression’ model for the formation of models of each stock. We then use the variance ratio profile together with a Monte Carlo simulation for the selection of models with potential predictability using data from 1 April 1999 to 30 December 2003. Unlike the approach of Burgess, we carry out White's Reality Check (Econometrica, 2000; 68, 1097–1126) in order to verify the existence of positive returns for the period outside the sample from 2 January 2004 to 28 August 2007. We use the strategies proposed by Sullivan, Timmermann and White (Journal of Finance, 1999; 54, 1647–1691) and Hsu and Kuan (Journal of Financial Econometrics, 2005; 3, 606–628) amounting to 26,410 simulated strategies. Finally, using the bootstrap methodology, with 1000 simulations, we find strong evidence of predictability in the models, including transaction costs. Copyright © 2015 John Wiley & Sons, Ltd.     

Emerging topics and new perspectives on HLA-G

Following the Fifth International Conference on non-classical HLA-G antigens (HLA-G), held in Paris in July 2009, we selected some topics which focus on emerging aspects in the setting of HLA-G functions. In particular, HLA-G molecules could play a role in: (1) various inflammatory disorders, such as multiple sclerosis, intracerebral hemorrhage, gastrointestinal, skin and rheumatic diseases, and asthma, where they may act as immunoregulatory factors; (2) the mechanisms to escape immune surveillance utilized by several viruses, such as human cytomegalovirus, herpes simplex virus type 1, rabies virus, hepatitis C virus, influenza virus type A and human immunodeficiency virus 1 (HIV-1); and (3) cytokine/chemokine network and stem cell transplantation, since they seem to modulate cell migration by the downregulation of chemokine receptor expression and mesenchymal stem cell activity blocking of effector cell functions and the generation of regulatory T cells. However, the immunomodulatory circuits mediated by HLA-G proteins still remain to be clarified.     

Exome sequencing identifies MAX mutations as a cause of hereditary pheochromocytoma

Hereditary pheochromocytoma (PCC) is often caused by germline mutations in one of nine susceptibility genes described to date, but there are familial cases without mutations in these known genes. We sequenced the exomes of three unrelated individuals with hereditary PCC (cases) and identified mutations in MAX, the MYC associated factor X gene. Absence of MAX protein in the tumors and loss of heterozygosity caused by uniparental disomy supported the involvement of MAX alterations in the disease. A follow-up study of a selected series of 59 cases with PCC identified five additional MAX mutations and suggested an association with malignant outcome and preferential paternal transmission of MAX mutations. The involvement of the MYC-MAX-MXD1 network in the development and progression of neural crest cell tumors is further supported by the lack of functional MAX in rat PCC (PC12) cells and by the amplification of MYCN in neuroblastoma and suggests that loss of MAX function is correlated with metastatic potential.     

Caveolar targeting links Kv1.3 with the insulin-dependent adipocyte physiology

The voltage-dependent potassium channel Kv1.3 participates in peripheral insulin sensitivity. Genetic ablation of Kv1.3 triggers resistance to diet-induced weight gain, thereby pointing to this protein as a pharmacological target for obesity and associated type II diabetes. However, this role is under intense debate because Kv1.3 expression in adipose tissue raises controversy. We demonstrated that Kv1.3 is expressed in white adipose tissue from humans and rodents. Moreover, other channels, such as Kv1.1, Kv1.2, Kv1.4 and especially Kv1.5, from the same Shaker family are also present. Although elevated insulin levels and adipogenesis remodel the Kv phenotype, which could lead to multiple heteromeric complexes, Kv1.3 markedly participates in the insulin-dependent regulation of glucose uptake in mature adipocytes. Adipocyte differentiation increased the expression of Kv1.3, which is targeted to caveolae by molecular interactions with caveolin 1. Using a caveolin 1-deficient 3T3-L1 adipocyte cell line, we demonstrated that the localization of Kv1.3 in caveolar raft structures is important for proper insulin signaling. Insulin-dependent phosphorylation of the channel occurs at the onset of insulin-mediated signaling. However, when Kv1.3 was spatially outside of these lipid microdomains, impaired phosphorylation was exhibited. Our data shed light on the putative role of Kv1.3 in weight gain and insulin-dependent responses contributing to knowledge about adipocyte physiology.     

A new species of Austrorhynchus (Platyhelminthes: Kalyptorhynchia) from King George Island (Maritime Antarctic)

A new species of the turbellarian genus Austrorhynchus (Kalyptorhynchia: Polycystididae) was found in King George Island (South Shetland Islands, Maritime Antarctic). The new species has eyes and white to greyish parenchyma. The type II prostate stylet has a funnel and a slightly bent tube with an inner stylet extending throughout its length; a strongly bent hook of about the same size as the tube is present. The type III prostate stylet has a foot and a style connected by a bridge, defining a broad window; the style expands to a comb-bearing plate with large teeth; the foot continues into a narrow flagellum with a distal expansion and a row of fine teeth. The species is oviparous. It can be distinguished from the other known Austrorhynchus species by the shape and size of the type II and type III prostate stylets. Out of the five known species of Austrorhynchus presenting a window in the type III stylet, the four more similar ones are found in the northern arm of the Scotia Arc and the Weddell Sea area. This is the first report of Kalyptorhynchia from the Antarctic portion of the Scotia Sea, and it confirms previous observations that the true number of Austrorhynchus species in the area must be higher than what is currently known.

http://www.zoobank.org/urn:lsid:zoobank.org:pub:098ADF23-763B-41F6-A2F5-54F6AA8620E8     

ASIP and TYR pigmentation variants associate with cutaneous melanoma and basal cell carcinoma

Fair color increases risk of cutaneous melanoma (CM) and basal cell carcinoma (BCC). Recent genome-wide association studies have identified variants affecting hair, eye and skin pigmentation in Europeans. Here, we assess the effect of these variants on risk of CM and BCC in European populations comprising 2,121 individuals with CM, 2,163 individuals with BCC and over 40,000 controls. A haplotype near ASIP, known to affect a similar spectrum of pigmentation traits as MC1R variants, conferred significant risk of CM (odds ratio (OR) = 1.45, P = 1.2 x 10(-9)) and BCC (OR = 1.33, P = 1.2 x 10(-6)). The variant in TYR encoding the R402Q amino acid substitution, previously shown to affect eye color and tanning response, conferred risk of CM (OR = 1.21, P = 2.8 x 10(-7)) and BCC (OR = 1.14, P = 6.1 x 10(-4)). An eye color variant in TYRP1 was associated with risk of CM (OR = 1.15, P = 4.6 x 10(-4)). The association of all three variants is robust with respect to adjustment for the effect of pigmentation.     

Active-site remodelling in the bifunctional fructose-1,6-bisphosphate aldolase/phosphatase

Fructose-1,6-bisphosphate (FBP) aldolase/phosphatase is a bifunctional, thermostable enzyme that catalyses two subsequent steps in gluconeogenesis in most archaea and in deeply branching bacterial lineages. It mediates the aldol condensation of heat-labile dihydroxyacetone phosphate (DHAP) and glyceraldehyde-3-phosphate (GAP) to FBP, as well as the subsequent, irreversible hydrolysis of the product to yield the stable fructose-6-phosphate (F6P) and inorganic phosphate; no reaction intermediates are released. Here we present a series of structural snapshots of the reaction that reveal a substantial remodelling of the active site through the movement of loop regions that create different catalytic functionalities at the same location. We have solved the three-dimensional structures of FBP aldolase/phosphatase from thermophilic Thermoproteus neutrophilus in a ligand-free state as well as in complex with the substrates DHAP and FBP and the product F6P to resolutions up to 1.3??. In conjunction with mutagenesis data, this pinpoints the residues required for the two reaction steps and shows that the sequential binding of additional Mg(2+) cations reversibly facilitates the reaction. FBP aldolase/phosphatase is an ancestral gluconeogenic enzyme optimized for high ambient temperatures, and our work resolves how consecutive structural rearrangements reorganize the catalytic centre of the protein to carry out two canonical reactions in a very non-canonical type of bifunctionality.     

Collaborative Capability Design: Redundancy of Potentialities

In this study we extend the socio-ecological concept of two contrasting design principles applicable to all work systems. Reframing those design principles as strategic as well as operational choices leads us to propose a third design principle, Design Principle 3 (DP3), which has remained undeveloped in social ecology. We call this design principle Redundancy of Potentialities and demonstrate its application in transorganizational work systems. We argue that DP3 is at the core of socio-ecological practice and is therefore appropriate for coping with the highly turbulent environments now experienced in many industries and fields. We offer several illustrations of DP3 in practice and draw implications for enhancing capabilities for creative collaboration in inter-organizational fields through deliberate attention to design.