Turnover, account value and diversification of real traders: evidence of collective portfolio optimizing behavior

Despite the availability of very detailed data on financial market, agent-based modeling is hindered by the lack of information about real trader behavior. This makes it impossible to validate agent-based models, which are thus reverse-engineering attempts. This work is a contribution to the building of a set of stylized facts about the traders themselves. Using the client database of Swissquote Bank SA, the largest on-line Swiss broker, we find empirical relationships between turnover, account values and the number of assets in which a trader is invested. A theory based on simple mean-variance portfolio optimization that crucially includes variable transaction costs is able to reproduce faithfully the observed behaviors. We finally argue that our results bring into light the collective ability of a population to construct a mean-variance portfolio that takes into account the structure of transaction costsComment: 26 pages, 9 figures, Fig. 8 fixe

The Abundance of Pink-Pigmented Facultative Methylotrophs in the Root Zone of Plant Species in Invaded Coastal Sage Scrub Habitat

Pink-pigmented facultative methylotrophic bacteria (PPFMs) are associated with the roots, leaves and seeds of most terrestrial plants and utilize volatile C1 compounds such as methanol generated by growing plants during cell division. PPFMs have been well studied in agricultural systems due to their importance in crop seed germination, yield, pathogen resistance and drought stress tolerance. In contrast, little is known about the PPFM abundance and diversity in natural ecosystems, let alone their interactions with non-crop species. Here we surveyed PPFM abundance in the root zone soil of 5 native and 5 invasive plant species along ten invasion gradients in Southern California coastal sage scrub habitat. PPFMs were present in every soil sample and ranged in abundance from 102 to 105 CFU/g dry soil. This abundance varied significantly among plant species. PPFM abundance was 50% higher in the root zones of annual or biennial species (many invasives) than perennial species (all natives). Further, PPFM abundance appears to be influenced by the plant community beyond the root zone; pure stands of either native or invasive species had 50% more PPFMs than mixed species stands. In sum, PPFM abundance in the root zone of coastal sage scrub plants is influenced by both the immediate and surrounding plant communities. The results also suggest that PPFMs are a good target for future work on plant-microorganism feedbacks in natural ecosystems

Advances in MRI Assessment of Gliomas and Response to Anti-VEGF Therapy

Bevacizumab is thought to normalize tumor vasculature and restore the blood–brain barrier, decreasing enhancement and peritumoral edema. Conventional measurements of tumor response rely upon dimensions of enhancing tumor. After bevacizumab treatment, glioblastomas are more prone to progress as nonenhancing tumor. The RANO (Response Assessment in Neuro-Oncology) criteria for glioma response use fluid-attenuated inversion recovery (FLAIR)/T2 hyperintensity as a surrogate for nonenhancing tumor; however, nonenhancing tumor can be difficult to differentiate from other causes of FLAIR/T2 hyperintensity (eg, radiation-induced gliosis). Due to these difficulties, recent efforts have been directed toward identifying new biomarkers that either predict treatment response or accurately measure response of both enhancing and nonenhancing tumor shortly after treatment initiation. This will allow for earlier treatment decisions, saving patients from the adverse effects of ineffective therapies while allowing them to try alternative therapies sooner. An active area of research is the use of physiologic imaging, which can potentially detect treatment effects before changes in tumor size are evident

Development and use of genic molecular markers (GMMs) for construction of a transcript map of chickpea (Cicer arietinum L.)

A transcript map has been constructed by the development and integration of genic molecular markers (GMMs) including single nucleotide polymorphism (SNP), genic microsatellite or simple sequence repeat (SSR) and intron spanning region (ISR)-based markers, on an inter-specific mapping population of chickpea, the third food legume crop of the world and the first food legume crop of India. For SNP discovery through allele re-sequencing, primer pairs were designed for 688 genes/expressed sequence tags (ESTs) of chickpea and 657 genes/ESTs of closely related species of chickpea. High-quality sequence data obtained for 220 candidate genic regions on 2–20 genotypes representing 9 Cicer species provided 1,893 SNPs with an average frequency of 1/35.83 bp and 0.34 PIC (polymorphism information content) value. On an average 2.9 haplotypes were present in 220 candidate genic regions with an average haplotype diversity of 0.6326. SNP2CAPS analysis of 220 sequence alignments, as mentioned above, provided a total of 192 CAPS candidates. Experimental analysis of these 192 CAPS candidates together with 87 CAPS candidates identified earlier through in silico mining of ESTs provided scorable amplification in 173 (62.01%) cases of which predicted assays were validated in 143 (82.66%) cases (CGMM). Alignments of chickpea unigenes with Medicago truncatula genome were used to develop 121 intron spanning region (CISR) markers of which 87 yielded scorable products. In addition, optimization of 77 EST-derived SSR (ICCeM) markers provided 51 scorable markers. Screening of easily assayable 281 markers including 143 CGMMs, 87 CISRs and 51 ICCeMs on 5 parental genotypes of three mapping populations identified 104 polymorphic markers including 90 markers on the inter-specific mapping population. Sixty-two of these GMMs together with 218 earlier published markers (including 64 GMM loci) and 20 other unpublished markers could be integrated into this genetic map. A genetic map developed here, therefore, has a total of 300 loci including 126 GMM loci and spans 766.56 cM, with an average inter-marker distance of 2.55 cM. In summary, this is the first report on the development of large-scale genic markers including development of easily assayable markers and a transcript map of chickpea. These resources should be useful not only for genome analysis and genetics and breeding applications of chickpea, but also for comparative legume genomics

Production of Single W Bosons at LEP

We report on the observation of single W boson production in a data sample collected by the L3 detector at LEP2. The signal consists of large missing energy final states with a single energetic lepton or two hadronic jets. The cross-section is measured to be $0.61^{+0.43}_{-0.33} \pm 0.05 \; \rm{pb}$ at the centre of mass energy \sqrt{s}=172 \GeV{}, consistent with the Standard Model expectation. From this measurement the following limits on the anomalous $\gamma$WW gauge couplings are derived at 95\% CL: $\rm -3.6 \Delta \kappa_\gamma 1.5$ and $\rm -3.6 \lambda_\gamma 3.6$

Determination of the number of light neutrino species from single photon production at LEP

A determination of the number of light neutrino families performed by measuring the cross section of single photon production in \ee\ collision near the \Zo\ resonance is reported. From an integrated luminosity of $100~\mathrm{pb^{-1}}$, collected during the years 1991--94, we have observed 2091 single photon candidates with an energy above 1~\GeV\ in the polar angular region $45^\circ < \theta_\gamma < 135^\circ$. From a maximum likelihood fit to the single photon cross section, the \Zo\ decay width into invisible particles is measured to be \Ginv = 498 \pm 12 \mathrm{(stat)} \pm 12 \mathrm{(sys)~MeV}. Using the Standard Model couplings of neutrinos to the \Zo, the number of light neutrino species is determined to be $N_\nu = 2.98 \pm 0.07 (\mathrm{stat}) \pm 0.07 (\mathrm{sys}).

Search for R-Parity Breaking Sneutrino Exchange at LEP

We report on a search for R--parity breaking effects due to supersymmetric tau--sneutrino exchange in the reactions e+e- to e+e- and e+e- to mu+mu- at centre--of--mass energies from 91~{\GeV} to 172~{\GeV}, using the L3 detector at LEP. No evidence for deviations from the Standard Model expectations of the measured cross sections and forward--backward asymmetries for these reactions is found. Upper limits for the couplings $\lambda_{131}$ and $\lambda_{232}$ for sneutrino masses up to m_{\SNT} \leq 190~\GeV are determined from an analysis of the expected effects due to tau sneutrino exchange

Measurement of the Average Lifetime of b-Hadrons in Z Decays

We present a measurement of the average b-hadron lifetime ${\rm \tau_b}$ at the $\mathrm{e^+e^-} \,$ collider LEP. Using hadronic Z decays collected in the period from 1991 to 1994, two independent analyses have been performed. In the first one, the b-decay position is reconstructed as a secondary vertex of hadronic b-decay particles. The second analysis is an updated measurement of ${\rm \tau_b}$ using the impact parameter of leptons with high momentum and high transverse momentum. The combined result is \begin{center} ${\rm \tau_b= [ 1549 \pm 9 \, (stat) \, \pm 15 \, (syst) ] \; fs \,}$ . \end{center} In addition, we measure the average charged b-decay multiplicity ${\rm \langle n_{\rm b}} \rangle$ and the normalized average b-energy ${\rm \langle x_E \rangle_{\rm b}}$ at LEP to be \begin{center} ${\rm \langle n_{\rm b} \rangle = 4.90 \pm 0.04 \ (stat) \pm 0.11 \, (syst)}$ , \end{center} \begin{center} ${\rm \langle x_E \rangle_{\rm b} = 0.709 \pm 0.004 \, (stat + syst).}$ \end{center

Local multiplicity fluctuations in hadronic Z decay

Local multiplicity fluctuations in hadronic Z decays are studied using the L3 detector at LEP. Bunching parameters are used for the first time in addition to the normalised factorial moment method. The bunching parameters directly demonstrate that the fluctuations in rapidity are multifractal. Monte Carlo models show overall agreement with the data, reproducing the trend, although not always the magnitude, of the factorial moments and bunching parameters