Imagining a Silicon Valley: technological and conceptual connectivity in Kenya's BPO and software development sectors

This is a paper about expectations surrounding a potentially highly transformative moment in East Africa's history: the arrival of underwater fibre-optic broadband communications cables into the Indian Ocean port of Mombasa. It combines a media content analysis with findings from interviews with business owners in Kenya's nascent business process outsourcing (BPO) and software development sectors in order to explore how such moments of technological 'connectivity' are imagined, marketed and enacted within economic development. It argues that connectivity is not just a matter of boosting physical/material capacity but also about redressing conceptual connectivity; bringing places 'closer together' involves rehabilitating the images of places in peoples' minds and removing imagined senses of distance. As such, technologies of connectivity are marketed not just as tools of altered communications affordances, but more importantly, as momentary opportunities for revisiting the image of places from afar. Additionally, the cables reveal the importance of fostering internal linkages in order to better build international recognition and connections. 'Moments of expectation' that surround new ICT technologies reveal how discourse and representation play a strong role in enabling markets to form and change. The very idea of 'connectivity' itself is driving plans and policies throughout the region.ASC – Publicaties niet-programma gebonde

Mini Z' Burst from Relic Supernova Neutrinos and Late Neutrino Masses

In models in which neutrinos are light, due to a low scale of symmetry breaking, additional light bosons are generically present. We show that the interaction between diffuse relic supernova neutrinos (RSN) and the cosmic background neutrinos, via exchange of these light scalars, can result in a dramatic change of the supernova (SN) neutrinos flux. Measurement of this effect with current or future experiments can provide a spectacular direct evidence for the low scale models. We demonstrate how the observation of neutrinos from SN1987A constrains the symmetry breaking scale of the above models. We also discuss how current and future experiments may confirm or further constrain the above models, either by detecting the ``accumulative resonance'' that diffuse RSN go through or via a large suppression of the flux of neutrinos from nearby < O(Mpc) SN bursts.Comment: 24 pages, 8 figures, version to be published in JHE

Suppressing the μ\mu and neutrino masses by a superconformal force

The idea of Nelson and Strassler to obtain a power law suppression of parameters by a superconformal force is applied to understand the smallness of the $\mu$ parameter and neutrino masses in R-parity violating supersymmetric standard models. We find that the low-energy sector should contain at least another pair of Higgs doublets, and that a suppression of \lsim O(10^{-13}) for the $\mu$ parameter and neutrino masses can be achieved generically. The superpotential of the low-energy sector happens to possess an anomaly-free discrete R-symmetry, either $R_3$ or $R_6$, which naturally suppresses certain lepton-flavor violating processes, the neutrinoless double beta decays and also the electron electric dipole moment. We expect that the escape energy of the superconformal sector is \lsim O(10) TeV so that this sector will be observable at LHC. Our models can accommodate to a large mixing among neutrinos and give the same upper bound of the lightest Higgs mass as the minimal supersymmetric standard model.Comment: 24 page

SUSY GUT Model Building

I discuss an evolution of SUSY GUT model building, starting with the construction of 4d GUTs, to orbifold GUTs and finally to orbifold GUTs within the heterotic string. This evolution is an attempt to obtain realistic string models, perhaps relevant for the LHC. This review is in memory of the sudden loss of Julius Wess, a leader in the field, who will be sorely missed.Comment: 24 pages, 14 figures, lectures given at PiTP 2008, Institute for Advanced Study, Princeton, to be published in the European Physical Journal

Search for the Proton Decay Mode proton to neutrino K+ in Soudan 2

We have searched for the proton decay mode proton to neutrino K+ using the one-kiloton Soudan 2 high resolution calorimeter. Contained events obtained from a 3.56 kiloton-year fiducial exposure through June 1997 are examined for occurrence of a visible K+ track which decays at rest into mu+ nu or pi+ pi0. We found one candidate event consistent with background, yielding a limit, tau/B > 4.3 10^{31} years at 90% CL with no background subtraction.Comment: 13 pages, Latex, 3 tables and 3 figures, Accepted by Physics Letters

On Uniqueness of the Jump Process in Quantum Measurement Theory

We prove that, contrary to the standard quantum theory of continuous observation, in the formalism of Event Enhanced Quantum Theory the stochastic process generating individual sample histories of pairs (observed quantum system, observing classical apparatus) is unique. This result gives a rigorous basis to the previous heuristic argument of Blanchard and Jadczyk. Possible implications of this result are discussed.Comment: 31 pages, LaTeX, article; e-mail contact [email protected]

Long Lived Superheavy Dark Matter with Discrete Gauge Symmetries

The recently observed ultra-high energy (UHE) cosmic rays beyond the Greisen-Zatsepin-Kuzmin bound can be explained by the decays of some superheavy $X$ particles forming a part of dark matter in our universe. We consider various discrete gauge symmetries ${\bf Z}_N$ to ensure the required long lifetime ($\tau_X \simeq 10^{10}-10^{22} years$) of the $X$ particle to explain the UHE cosmic rays in the minimal supersymmetric standard model (MSSM) with massive Majorana neutrinos. We show that there is no anomaly-free discrete gauge symmetry to make the lifetime of the $X$ particle sufficiently long in the MSSM with the $X$ particle. We find, however, possible solutions to this problem especially by enlarging the particle contents in the MSSM. We show a number of solutions introducing an extra pair of singlets $Y$ and $\bar{Y}$ which have fractional ${\bf Z}_N$ (N=2,3) charges. The present experimental constraints on the $X$ particle are briefly discussed.Comment: 27 pages, Late

Surface antigen profiles of leukocytes and melanoma cells in lymph node metastases are associated with survival in AJCC stage III melanoma patients

There is an urgent need to identify more accurate prognostic biomarkers in melanoma patients, particularly in those with metastatic disease. This study aimed to identify melanoma and leukocyte surface antigens predictive of survival in a prospective series of AJCC stage IIIb/c melanoma patients (n = 29). Live cell suspensions were prepared from melanoma metastases within lymph nodes (LN). The suspensions were immuno-magnetically separated into CD45+ (leukocyte) and CD45− (non-hematopoietic, enriched melanoma cell) fractions. Surface antigens on CD45− and CD45+ cell populations were profiled using DotScan™ microarrays (Medsaic Pty. Ltd.) and showed differential abundance levels for 52 and 78 antigens respectively. Associations of the surface profiles with clinicopathologic and outcome data (median follow-up 35.4 months post LN resection) were sought using univariate (log-rank test) and multivariate (Wald’s test; modelled with patient’s age, gender and AJCC staging at LN recurrence) survival models. CD9 (p = 0.036), CD39 (p = 0.004) and CD55 (p = 0.005) on CD45+ leukocytes were independently associated with distant metastasis-free survival using multivariate analysis. Leukocytes with high CD39 levels were also significantly associated with increased overall survival (OS) in multivariate analysis (p = 0.016). LNs containing leukocytes expressing CD11b (p = 0.025), CD49d (p = 0.043) and CD79b (p = 0.044) were associated with reduced OS on univariate analysis. For enriched melanoma cells (CD45− cell populations), 11 surface antigens were significantly correlated with the disease-free interval (DFI) between diagnosis of culprit primary melanoma and LN metastasis resection. Nine antigens on CD45+ leukocytes also correlated with DFI. Following validation in independent datasets, surface markers identified here should enable more accurate determination of prognosis in stage III melanoma patients and provide better risk stratification of patients entering clinical trials

A Constrained Standard Model from a Compact Extra Dimension

A SU(3) \times SU(2) \times U(1) supersymmetric theory is constructed with a TeV sized extra dimension compactified on the orbifold S^1/(Z_2 \times Z_2'). The compactification breaks supersymmetry leaving a set of zero modes which correspond precisely to the states of the 1 Higgs doublet standard model. Supersymmetric Yukawa interactions are localized at orbifold fixed points. The top quark hypermultiplet radiatively triggers electroweak symmetry breaking, yielding a Higgs potential which is finite and exponentially insensitive to physics above the compactification scale. This potential depends on only a single free parameter, the compactification scale, yielding a Higgs mass prediction of 127 \pm 8 GeV. The masses of the all superpartners, and the Kaluza-Klein excitations are also predicted. The lightest supersymmetric particle is a top squark of mass 197 \pm 20 GeV. The top Kaluza-Klein tower leads to the \rho parameter having quadratic sensitivity to unknown physics in the ultraviolet.Comment: 31 pages, Latex, 2 eps figures, minor correction

Hierarchical Neutrino Mass Matrices, CP violation and Leptogenesis

In this work we study examples of hierarchical neutrino mass matrices inspired by family symmetries, compatible with experiments on neutrino oscillations, and for which there is a connection among the low energy CP violation phase associated to neutrino oscillations, the phases appearing in the amplitude of neutrinoless double beta decay, and the phases relevant for leptogenesis. In particular, we determine the predictions from a texture based on an underlying SU(3) family symmetry together with a GUT symmetry, and a strong hierarchy for the masses of the heavy right handed Majorana masses. We also give some examples of inverted hierarchies of neutrino masses, which may be motivated in the context of U(1) family symmetries.Comment: 34 pages. Replaced with published version -typos, corrections and references adde