Running out of time

This is the author accepted manuscript. The final version is available from Springer Nature via the DOI in this record.Choosing how much to take and how much to preserve from our environment is a challenging task, and every small decision counts. A behavioural experiment sheds new light on how time pressure negatively affects sustainability decisions

Singularities in positive characteristic, stratification and simplification of the singular locus

We introduce an upper semi-continuous function that stratifies the highest multiplicity locus of a hypersurface in arbitrary characteristic (over a perfect field). The blow-up along the maximum stratum defined by this function leads to a form of simplification of the singularities, also known as a reduction to the monomial case.Comment: Several typos corrected. Minor improvements on the presentation of the published pape

Distribution and Potential Impact of Feral Cotton on the Reintroduction of Cotton in the Southern Highlands, Tanzania

Cotton (Gossypium hirsutum) production is limited by bollworms that cause declining yields and poor lint quality. Generally, farmers manage pests by employing Integrated Pest Management (IPM) strategies, which include biological, cultural, physical and chemical approaches. Pest management by quarantine and pesticide sprays reduce production area and lead to resistance build-up. The Red bollworm, Dipsaropsis castanea is an important cotton pest of significant economical importance to Tanzania. The pest invaded the Southern Highlands (SH) of Tanzania in 1960’s from southern neighbour countries causing the Government to quarantine cottonproduction from 1968 as measure to limit the spread of the red bollworm. Transgenic Bt cotton with insecticidal properties presents a potential solution to the bollworm infestation in Tanzania. However, concerns associated with transgenic crops viz.; transgene flow to wild and feral relatives, increased potential for resistance evolution, need to be addressed prior to adoption of any transgenic crop. Information from national herbaria, research stations and a field survey established sparse distribution and diversity of feral cotton species G. barbadense, an exotic ornamental from Brazil though as isolated garden plants. Informal interviews revealed medicinal and fibre value of the ornamental. Diploid wild cotton relatives such as G. longicalyx and Gossypoides kirkii were also recorded but are incompatible to G. hirsutum. Field observations indicate continued red bollworm presence in the SH on feral cotton, but low in number as plants are few and isolated. Cluster analysis indicates presence of hybrid remnants of G. hirsutum and G. barbadense suggesting potential for gene flow.Keywords: Bt cotton, bollworms, quarantine, insecticides, insect resistance, feral cotton, refuge plan

Broadband multi-wavelength campaign on PKS 2005-489

The spectral energy distribution (SED) of high-frequency peaked BL Lac objects (HBL) is characterized by two peaks: one in the UV-X-ray and one in the GeV-TeV regime. An interesting object for analyzing these broadband characteristics is PKS 2005-489, which in 2004 showed the softest TeV spectrum ever measured. In 2009, a multi-wavelength campaign has been conducted with, for the first time, simultaneous observations by H.E.S.S. (TeV), Fermi/LAT (GeV), RXTE (keV), Swift (keV, UV, optical) and ATOM (optical) to cover the two peaks of the SED. During this campaign PKS 2005-489 underwent a high state in all wavebands which gives the opportunity to study in detail the emission processes of a high state of this interesting HBL.Comment: 2009 Fermi Symposium; eConf Proceedings C09112

WHEN A FIRE LEADS TO A DRINK: ENHANCEMENT OF ALCOHOL-SEEKING BY MICROINJECTIONS OF NICOTINE DIRECTLY INTO THE REWARD NEUROCIRCUITRY

poster abstractAlcohol addiction is a cyclical disorder that is characterized by periods of alcohol consumption and abstinence. The periods of abstinence are frequently brief, and the rate of relapse to alcohol consumption is typically higher than 95% within a year. Most alcoholics are not just alcoholics. The vast majority (80-95%) of alcoholics also concurrently use, or are dependent on, nicotine. During periods of alcohol abstinence, nicotine use dramatically increases. The use of nicotine can potentiate self-reported craving for alcohol and the amount of alcohol used following a relapse episode. The goal of the present project was to determine the biological basis of nicotine’s ability to stimulate alcohol (EtOH)-seeking in a rodent model of alcoholism (alcohol-preferring [P] rat). Specifically, the current project examined the effect of nicotine on EtOH-seeking when administered directly into the brain reward neurocircuit (posterior Ventral Tegmental Area – pVTA). In order to determine the neurotransmitter systems regulating nicotine’s ability to enhance EtOH-seeking when administered into the pVTA, two subsequent studies examined the effect of co-administration of nicotine with a acetylcholine nicotine receptor (AchN) antagonist (mecamylamine (MEC)) or with a serotonin-3 (5HT3) receptor antagonist (zacopride (Zac)). Nicotine binds with high affinity to both the AchN and 5HT3 receptors. The data collected indicated that at very low concentrations nicotine microinjected into the pVTA increased EtOH-seeking in P rats. Co-administration of mecamylamine or zacopride blocked nicotine’s ability to potentiate EtOH-seeking. Overall, the results show that nicotine can enhance alcohol-seeking behaviors through activation of the AchN and 5-HT3 receptors in pVTA. The clinical implication of the data set would be that to reduce the amount of alcohol-craving, which could lead to relapse, nicotine use should also be terminated

Failure to CAPTCHA Attention: Null Results from an Honesty Priming Experiment in Guatemala

This is the author accepted manuscript. The final version is available from MDPI via the DOI in this record.We report results from a large online randomised tax experiment in Guatemala. The trial involves short messages and choices presented to taxpayers as part of a CAPTCHA pop-up window immediately before they file a tax return, with the aim of priming honest declarations. In total our sample includes 627,242 taxpayers and 3,232,430 tax declarations made over four months. Treatments include: honesty declaration; information about public goods; information about penalties for dishonesty, questions allowing a taxpayer to choose which public good they think tax money should be spent on; or questions allowing a taxpayer to state a view on the penalty for not declaring honestly. We find no impact of any of these treatments on the average amount of tax declared. We discuss potential causes for this null effect and implications for ‘online nudges’ around honesty priming.This project would not have been possible without the collaboration and commitment shown by the Superintendencia de Administración Tributaria, Guatemala’s Tax Authority. We thank the institution and the team led by Mario Figueroa and Hugo Roldán for their support, patience, time, and resources. Finally, we are grateful for the help and support of colleagues at the Behavioural Insights Team, and particularly to Alex Tupper for his assistance in developing and testing our randomisation method

Effect of spin orbit scattering on the magnetic and superconducting properties of nearly ferromagnetic metals: application to granular Pt

We calculate the effect of scattering on the static, exchange enhanced, spin susceptibility and show that in particular spin orbit scattering leads to a reduction of the giant moments and spin glass freezing temperature due to dilute magnetic impurities. The harmful spin fluctuation contribution to the intra-grain pairing interaction is strongly reduced opening the way for BCS superconductivity. We are thus able to explain the superconducting and magnetic properties recently observed in granular Pt as due to scattering effects in single small grains.Comment: 9 pages 3 figures, accepted for publication in Phys. Rev. Letter

1ES 0229+200: An extreme blazar with a very high minimum Lorentz factor

The blazar 1ES 0229+200 is a high frequency peaked BL Lac object with a hard TeV spectrum extending to 10 TeV. Its unusual spectral characteristics make it a frequently used probe for intergalactic radiation and magnetic fields. With new, simultaneous observations in the optical, ultraviolet (UV) and X-rays, the synchrotron emission is probed in great detail. The X-ray emission varies by a factor of ~2 in 2009, while being rather stable in 2010. The X-ray spectrum is very hard (\Gamma ~ 1.8) and it shows an indication of excess absorption above the Galactic value. The X-ray emission is detected up to ~100 keV without any significant cut-off, thus 1ES 0229+200 belongs to the class of extreme blazars. The simultaneous measured, host galaxy- and extinction-corrected optical and UV fluxes illustrate that the cut-off of the low energy part of the synchrotron emission is located in the UV regime. The minimum energy of the electron distribution has to be rather high to account for this cut-off. This implies that there is a narrow-band energy distribution function of radiating electrons, which is responsible for the unusually hard TeV spectrum. Other extreme blazars have similar synchrotron peak frequencies but much softer TeV spectra, hence 1ES 0229+200 has one of the highest inverse Compton (IC) peak frequency and the narrowest electron distribution among the extreme blazars known to date.Comment: accepted for publication in Astronomy&Astrophysic

Dirichlet Boundary Value Problems of the Ernst Equation

We demonstrate how the solution to an exterior Dirichlet boundary value problem of the axisymmetric, stationary Einstein equations can be found in terms of generalized solutions of the Backlund type. The proof that this generalization procedure is valid is given, which also proves conjectures about earlier representations of the gravitational field corresponding to rotating disks of dust in terms of Backlund type solutions.Comment: 22 pages, to appear in Phys. Rev. D, Correction of a misprint in equation (4