The solar influence on the probability of relatively cold UK winters in the future

Recent research has suggested that relatively cold UK winters are more common when solar activity is low (Lockwood et al 2010 Environ. Res. Lett. 5 024001). Solar activity during the current sunspot minimum has fallen to levels unknown since the start of the 20th century (Lockwood 2010 Proc. R. Soc. A 466 303–29) and records of past solar variations inferred from cosmogenic isotopes (Abreu et al 2008 Geophys. Res. Lett. 35 L20109) and geomagnetic activity data (Lockwood et al 2009 Astrophys. J. 700 937–44) suggest that the current grand solar maximum is coming to an end and hence that solar activity can be expected to continue to decline. Combining cosmogenic isotope data with the long record of temperatures measured in central England, we estimate how solar change could influence the probability in the future of further UK winters that are cold, relative to the hemispheric mean temperature, if all other factors remain constant. Global warming is taken into account only through the detrending using mean hemispheric temperatures. We show that some predictive skill may be obtained by including the solar effect

Predicting space climate change

The recent decline in the open magnetic flux of the Sun heralds the end of the Grand Solar Maximum (GSM) that has persisted throughout the space age, during which the largest‐fluence Solar Energetic Particle (SEP) events have been rare and Galactic Cosmic Ray (GCR) fluxes have been relatively low. In the absence of a predictive model of the solar dynamo, we here make analogue forecasts by studying past variations of solar activity in order to evaluate how long‐term change in space climate may influence the hazardous energetic particle environment of the Earth in the future. We predict the probable future variations in GCR flux, near‐Earth interplanetary magnetic field (IMF), sunspot number, and the probability of large SEP events, all deduced from cosmogenic isotope abundance changes following 24 GSMs in a 9300‐year record

The Band Gap in Silicon Nanocrystallites

The gap in semiconductor nanocrystallites has been extensively studied both theoretically and experimentally over the last two decades. We have compared a recent ``state-of-the-art'' theoretical calculation with a recent ``state-of-the-art'' experimental observation of the gap in Si nanocrystallite. We find that the two are in substantial disagreement, with the disagreement being more pronounced at smaller sizes. Theoretical calculations appear to over-estimate the gap. Recognizing that the experimental observations are for a distribution of crystallite sizes, we proffer a phenomenological model to reconcile the theory with the experiment. We suggest that similar considerations must dictate comparisons between the theory and experiment vis-a-vis other properties such as radiative rate, decay constant, absorption coefficient, etc.Comment: 5 pages, latex, 2 figures. (Submitted Physical Review B

Emiratisation: From policy to implementation

Emiratisation is an affirmative action policy of the United Arab Emirates Government that gives preferential hiring status to Emiratis over expatriates in order to preserve national identity, economic sustainability, and political stability. Although the policy has been practiced for a decade, the unemployment problem for Emiratis persists in the both private and public sectors. According to the United Arab Emirates (UAE) National Human Resources Development and Employment Authority, unemployment among Emiratis reached 12.7% or 290,000 in 2010. This surge in unemployment results from a massive reliance on foreign workforce employment throughout the UAE region. Given the absence of empirical data, this research relies on published government documents, personal interviews with public officials and private sector executives, and a survey questionnaire. Findings indicated that seven factors largely contribute to a disparity between the Emiratisation policy and its intended results. Several recommendations are offered for future research and possible Emiratisation policy revisions. © 2013 Inderscience Enterprises Ltd

Comparative genomics reveals multiple pathways to mutualism for tick-borne pathogens

Accelerated pipeline for DNA and amino acid sequences clustering

Effects of solar wind magnetosphere coupling recorded at different geomagnetic latitudes: Separation of directly-driven and storage/release systems

The effect on geomagnetic activity of solar wind speed, compared with that of the strength of the interplanetary magnetic field, differs with geomagnetic latitude. In this study we construct a new index based on monthly standard deviations in the H-component of the geomagnetic field for all geomagnetic latitudes. We demonstrate that for this index the response at auroral regions correlates best with interplanetary coupling functions which include the solar wind speed while mid- and low-latitude regions respond to variations in the interplanetary magnetic field strength. These results are used to isolate the responsible geomagnetic current systems

Ion charge states and potential geoeffectiveness: the role of coronal spectroscopy for space-weather forecasting

Severe space-weather is driven by interplanetary coronal mass ejections (ICMEs), episodic eruptions of solar plasma and magnetic flux that travel out through the heliosphere and can perturb the Earth’s magnetosphere, ionosphere and upper atmosphere. In order for space-weather forecasts to allow effective mitigating action, forecasts must be made as early as possible, necessitating identification of potentially “geoeffective” ICMEs close to the Sun. This presents two challenges. Firstly, geoeffectiveness is primarily determined by the magnetic field intensity and orientation, both of which are difficult to measure close to the Sun. Secondly, the magnetic field evolves in transit between the Sun and the Earth, sometimes in a highly non-linear way. Conversely, solar wind ion charge states, such as the ratio of O7+ to O6+, can be observed near the Sun through coronal spectroscopy and are fixed by the electron temperature at the coronal height where ion-electron collisions are last possible as the ICME erupts. After this point, they are said to be “frozen in” as they do not evolve further as the ICME propagates through the solar wind. In this study we show that ions charge states, while not geoeffective in and of themselves, act as strong markers for the geoeffectiveness of the ICME. The probability of severe space weather is around seven times higher in “hot” ICMEs than “cold” ICMEs, as defined by O7+/O6+. We suggest that coronal spectroscopy of ICMEs could complement current forecasting techniques, providing valuable additional information about potential geoeffectiveness

Semiquantitative theory of electronic Raman scattering from medium-size quantum dots

A consistent semiquantitative theoretical analysis of electronic Raman scattering from many-electron quantum dots under resonance excitation conditions has been performed. The theory is based on random-phase-approximation-like wave functions, with the Coulomb interactions treated exactly, and hole valence-band mixing accounted for within the Kohn-Luttinger Hamiltonian framework. The widths of intermediate and final states in the scattering process, although treated phenomenologically, play a significant role in the calculations, particularly for well above band gap excitation. The calculated polarized and unpolarized Raman spectra reveal a great complexity of features and details when the incident light energy is swept from below, through, and above the quantum dot band gap. Incoming and outgoing resonances dramatically modify the Raman intensities of the single particle, charge density, and spin density excitations. The theoretical results are presented in detail and discussed with regard to experimental observations.Comment: Submitted to Phys. Rev.

The radial pulsation of AI Aurigae

We present an analysis of eleven years of Stromgren by photometry of the red semiregular variable star AI Aurigae. An early period determination of 63.9 days is confirmed by the long-term light curve behaviour. The light curve shows semi-regular changes with a mean period of 65 days reaching an amplitude of 0.6 mag in some cycles. The b-y colour changes perfectly parallel the V light curve, suggesting radial oscillation to be the main reason for the observed variations. We estimate the main characteristics of the star (mass, radius, effective temperature) that suggest radial pulsation in fundamental or first overtone mode.Comment: 7 pages, 3 figures, accepted for publication in A&