Fertility control as a means of controlling bovine tuberculosis in badger (Meles meles) populations in south-west England: predictions from a spatial stochastic simulation model

A spatial stochastic simulation model was used to assess the potential of fertility control, based on a yet-to-be-developed oral bait-delivered contraceptive directed at females, for the control of bovine tuberculosis in badger populations in south-west England. The contraceptive had a lifelong effect so that females rendered sterile in any particular year remained so for the rest of their lives. The efficacy of fertility control alone repeated annually for varying periods of time was compared with a single culling operation and integrated control involving an initial single cull followed by annually repeated fertility control. With fertility control alone, in no instance was the disease eradicated completely while a viable badger population (mean group size of at least one individual) was still maintained. Near eradication of the disease (less than 1% prevalence) combined with the survival of a minimum viable badger population was only achieved under a very limited set of conditions, either with high efficiency of control (95%) over a short time period (1-3 years) or a low efficiency of control (20%) over an intermediate time period (10-20 years). Under these conditions, it took more than 20 years for the disease to decline to such low levels. A single cull of 80% efficiency succeeded in near eradication of the disease (below 1% prevalence) after a period of 6-8 years, while still maintaining a viable badger population. Integrated strategies reduced disease prevalence more rapidly and to lower levels than culling alone, although the mean badger group size following the onset of control was smaller. Under certain integrated strategies, principally where a high initial cull (80%) was followed by fertility control over a short (1-3 year) time period, the disease could be completely eradicated while a viable badger population was maintained. However, even under the most favourable conditions of integrated control, it took on average more than 12 years following the onset of control for the disease to disappear completely from the badger population. These results show that whilst fertility control would not be a successful strategy for the control of bovine tuberculosis in badgers if used alone, it could be effective if used with culling as part of an integrated strategy. This type of integrated strategy is likely to be more effective in terms of disease eradication than a strategy employing culling alone. However, the high cost of developing a suitable fertility control agent, combined with the welfare and conservation implications, are significant factors which should be taken into account when considering its possible use as a means of controlling bovine tuberculosis in badger populations in the UK

Quenched invariance principle for random walks in balanced random environment

We consider random walks in a balanced random environment in $\mathbb{Z}^d$, $d\geq 2$. We first prove an invariance principle (for $d\ge2$) and the transience of the random walks when $d\ge 3$ (recurrence when $d=2$) in an ergodic environment which is not uniformly elliptic but satisfies certain moment condition. Then, using percolation arguments, we show that under mere ellipticity, the above results hold for random walks in i.i.d. balanced environments.Comment: Published online in Probab. Theory Relat. Fields, 05 Oct 2010. Typo (in journal version) corrected in (26

Broad P V Absorption in the BALQSO, PG 1254+047: Column Densities, Ionizations and Metal Abundances in BAL Winds

This paper discusses the detection of P V 1118,1128 and other broad absorption lines (BALs) in archival HST spectra of the low-redshift BALQSO, PG 1254+047. The P V identification is secured by excellent redshift and profile coincidences with the other BALs, such as C IV 1548,1550 and Si IV 1393,1403, and by photoionization calculations showing that other lines near this wavelength, e.g. Fe III 1123, should be much weaker than P V. The observed BAL strengths imply that either 1) there are extreme abundance ratios such as [C/H] >~ +1.0, [Si/H] >~ +1.8 and [P/C] >~ +2.2, or 2) at least some of the lines are much more optically thick than they appear. I argue that the significant presence of P V absorption indicates severe line saturation, which is disguised in the observed (moderate-strength) BALs because the absorber does not fully cover the continuum source(s) along our line(s) of sight. Computed optical depths for all UV resonance lines show that the observed BALs are consistent with solar abundances if 1) the ionization parameter is at least moderately high, log U >~ -0.6, 2) the total hydrogen column density is log N_H(cm-2) >~ 22.0, and 3) the optical depths in strong lines like C IV and O VI 1032,1038 are >~25 and >~80, respectively. These optical depths and column densities are at least an order of magnitude larger than expected from the residual intensities in the BAL troughs, but they are consistent with the large absorbing columns derived from X-ray observations of BALQSOs. The outflowing BALR, at velocities from -15,000 to -27,000 km/s in PG 1254+047, is therefore a strong candidate for the X-ray absorber in BALQSOs.Comment: 16 pages (LaTeX) plus 8 pages of figures in one file (pg1254_figs.ps.gz), in press with Ap

Trapping in the random conductance model

We consider random walks on $\Z^d$ among nearest-neighbor random conductances which are i.i.d., positive, bounded uniformly from above but whose support extends all the way to zero. Our focus is on the detailed properties of the paths of the random walk conditioned to return back to the starting point at time $2n$. We show that in the situations when the heat kernel exhibits subdiffusive decay --- which is known to occur in dimensions $d\ge4$ --- the walk gets trapped for a time of order $n$ in a small spatial region. This shows that the strategy used earlier to infer subdiffusive lower bounds on the heat kernel in specific examples is in fact dominant. In addition, we settle a conjecture concerning the worst possible subdiffusive decay in four dimensions.Comment: 21 pages, version to appear in J. Statist. Phy

Regulatory policy and pharmaceutical innovation in the United Kingdom after Brexit: initial insights

Brexit was presented as an opportunity to promote innovation by breaking free from the European Union regulatory framework. Since the beginning of 2021 the Medicines and Healthcare products Regulatory Agency (MHRA) has operated as the independent regulatory agency for the United Kingdom. The MHRA's regulatory activity in 2021 was analyzed and compared to that of other international regulatory bodies. The MHRA remained reliant on EU regulatory decision-making for novel medicines and there were significant regulatory delays for a small number of novel medicines in the UK, the reasons being so far unclear. In addition, the MHRA introduced innovation initiatives, which show early promise for quicker authorization of innovative medicines for cancer and other areas of unmet need. Longer-term observation and analysis is needed to show the full impact of post-Brexit pharmaceutical regulatory policy

Does religion make a difference? : assessing the effects of Christian affiliation and practice on marital solidarity and divorce in Britain, 1985-2005

Marital breakdown rates were examined among 15,714 adults from the British Social Attitudes dataset for 1985-2005. Separation and divorce peaked at around 50 years of age, and increased significantly over the period of study. Ratios of separation or divorce were compared between respondents who had no religious affiliation and (a) Christian affiliates who attended church at least once a month, (b) Christian affiliates who attended church, but less than once a month, and (c) Christian affiliates who never attended church. The results showed that active Christians were 1.5 times less likely to suffer marital breakdown than non-affiliates, but there was no difference between affiliates who never attended church and those of no religion. Christians who attended infrequently were 1.3 times less likely to suffer marital breakdown compared to non-affiliates, suggesting that even infrequent attendance at church may have some significance for predicting the persistence of martial solidarity

The Alexander-Orbach conjecture holds in high dimensions

We examine the incipient infinite cluster (IIC) of critical percolation in regimes where mean-field behavior has been established, namely when the dimension d is large enough or when d>6 and the lattice is sufficiently spread out. We find that random walk on the IIC exhibits anomalous diffusion with the spectral dimension d_s=4/3, that is, p_t(x,x)= t^{-2/3+o(1)}. This establishes a conjecture of Alexander and Orbach. En route we calculate the one-arm exponent with respect to the intrinsic distance.Comment: 25 pages, 2 figures. To appear in Inventiones Mathematica

Optimizing information flow in small genetic networks. II: Feed forward interactions

Central to the functioning of a living cell is its ability to control the readout or expression of information encoded in the genome. In many cases, a single transcription factor protein activates or represses the expression of many genes. As the concentration of the transcription factor varies, the target genes thus undergo correlated changes, and this redundancy limits the ability of the cell to transmit information about input signals. We explore how interactions among the target genes can reduce this redundancy and optimize information transmission. Our discussion builds on recent work [Tkacik et al, Phys Rev E 80, 031920 (2009)], and there are connections to much earlier work on the role of lateral inhibition in enhancing the efficiency of information transmission in neural circuits; for simplicity we consider here the case where the interactions have a feed forward structure, with no loops. Even with this limitation, the networks that optimize information transmission have a structure reminiscent of the networks found in real biological systems

The Very Highly Ionized Broad Absorption Line System of the QSO SBS1542+541

We have analyzed the broad absorption line system of the bright (V=16.5) high-redshift (z=2.361) QSO SBS1542+541 using UV spectra from the HST FOS along with optical data from the MMT and the Steward Observatory 2.3m telescope. These spectra give continuous wavelength coverage from 1200 to 8000 Angstroms, corresponding to 340 to 2480 Angstroms in the QSO rest frame. This object therefore offers a rare opportunity to study broad absorption lines in the rest-frame extreme UV. We find that the absorption system is dominated by very high-ionization species, including O VI, NeVIII, and SiXII. We also identify apparently saturated broad Lyman-series lines of order Ly-gamma and higher. There is strong evidence for partial occultation of the QSO emission source, particularly from the higher-order Lyman lines which indicate a covered fraction less than 0.2. Overall, the data suggest a correlation between a larger covered fraction and a higher state of ionization. We suggest that the different covered fractions can be explained by either a special line of sight through a disk-like geometry or by the existence of density fluctuations of a factor >2 in the BAL gas. Our photoionization models of the system indicate a large column density and high ionization state similar to that found in X-ray ``warm absorbers''.Comment: 31 pages, 13 figures, to be published in Ap