Nest-site competition between bumblebees (Bombidae), social wasps (Vespidae) and cavity-nesting birds in Britain and the Western Palearctic

Capsule: There is no evidence of widespread significant nest-site competition in Britain or the Western Palearctic between cavity-nesting birds and bumblebees or social wasps. Aims: To investigate competition between cavity-nesting birds and bumblebees and wasps, particularly the range-expanding Tree Bumblebee, Saxon Wasp and European Hornet in Britain, and review evidence throughout the Western Palearctic. Methods: We compared field data from English and Polish studies of tits and woodpeckers breeding in nest-boxes and/or tree holes to assess nest-site competition with bumblebees and wasps. We reviewed the literature quantifying nest-site competition between birds and these insects in the Western Palearctic. Results: Bumblebees and wasps are capable of usurping small passerines from nests. In England, these insects commandeered a mean annual 4.1% of tit nests initiated in nest-boxes; occurrence of hornets showed a long-term increase, but not other wasps or bumblebees. Across the Western Palearctic, insect occupation of nest-boxes was generally low, and was lower in England than in Poland. No insects were discovered in tree cavities, including those created by woodpeckers (Picidae). Conclusion: Nest-site competition between cavity-nesting birds and bumblebees and wasps appears to be a ‘nest-box phenomenon’, which may occasionally interfere with nest-box studies, but appears negligible in natural nest-sites

Marking gender studies:the (Radical) value of creative-critical assessment

Feminist pedagogies have established the need to query power structures in terms of curriculum content and teaching praxis. However, the topic of student assessment poses difficulties: it is a means through which students’ performance is evaluated and quantified according to set institutionalised criteria that values particular forms of hegemonic knowledge. The following article presents a self-reflexive exploration of assessment within a Gender Studies module taught in the Autumn semesters of the 2017/18 and 2018/19 academic years at a UK university. The module was a core component of the institution’s MA in Gender Studies. This was an exciting opportunity to experiment with assessment styles corresponding to feminist pedagogies to help develop students’ and instructors’ disciplinary scope and explore the radical potential for creative-critical approaches to assessment. This article outlines some the challenges of employing alternative modes of learning and teaching from a feminist perspective and suggests some strategies to address these

Measurement of the B0-anti-B0-Oscillation Frequency with Inclusive Dilepton Events

The $B^0$-$\bar B^0$ oscillation frequency has been measured with a sample of 23 million \B\bar B pairs collected with the BABAR detector at the PEP-II asymmetric B Factory at SLAC. In this sample, we select events in which both B mesons decay semileptonically and use the charge of the leptons to identify the flavor of each B meson. A simultaneous fit to the decay time difference distributions for opposite- and same-sign dilepton events gives $\Delta m_d = 0.493 \pm 0.012{(stat)}\pm 0.009{(syst)}$ ps$^{-1}$.Comment: 7 pages, 1 figure, submitted to Physical Review Letter

Limit on Bs0B^0_s oscillation using a jet charge method

A lower limit is set on the B_{s}^{0} meson oscillation parameter \Delta m_{s} using data collected from 1991 to 1994 by the ALEPH detector. Events with a high transverse momentum lepton and a reconstructed secondary vertex are used. The high transverse momentum leptons are produced mainly by b hadron decays, and the sign of the lepton indicates the particle/antiparticle final state in decays of neutral B mesons. The initial state is determined by a jet charge technique using both sides of the event. A maximum likelihood method is used to set a lower limit of \, \Delta m_{s}. The 95\% confidence level lower limit on \Delta m_s ranges between 5.2 and 6.5(\hbar/c^{2})~ps^{-1} when the fraction of b quarks from Z^0 decays that form B_{s}^{0} mesons is varied from 8\% to 16\%. Assuming that the B_{s}^{0} fraction is 12\%, the lower limit would be \Delta m_{s} 6.1(\hbar/c^{2})~ps^{-1} at 95\% confidence level. For x_s = \Delta m_s \, \tau_{B_s}, this limit also gives x_s 8.8 using the B_{s}^{0} lifetime of \tau_{B_s} = 1.55 \pm 0.11~ps and shifting the central value of \tau_{B_s} down by 1\sigma

Measurement of the Bs0^0_s lifetime and production rate with Ds−l+^-_s l^+ combinations in Z decays

The lifetime of the \bs meson is measured in approximately 3 million hadronic Z decays accumulated using the ALEPH detector at LEP from 1991 to 1994. Seven different \ds decay modes were reconstructed and combined with an opposite sign lepton as evidence of semileptonic \bs decays. Two hundred and eight \dsl candidates satisfy selection criteria designed to ensure precise proper time reconstruction and yield a measured \bs lifetime of \mbox{\result .} Using a larger, less constrained sample of events, the product branching ratio is measured to be \mbox{\pbrresult