Equilibrium Distribution of Mutators in the Single Fitness Peak Model

This paper develops an analytically tractable model for determining the equilibrium distribution of mismatch repair deficient strains in unicellular populations. The approach is based on the single fitness peak (SFP) model, which has been used in Eigen's quasispecies equations in order to understand various aspects of evolutionary dynamics. As with the quasispecies model, our model for mutator-nonmutator equilibrium undergoes a phase transition in the limit of infinite sequence length. This "repair catastrophe" occurs at a critical repair error probability of $\epsilon_r = L_{via}/L$, where $L_{via}$ denotes the length of the genome controlling viability, while $L$ denotes the overall length of the genome. The repair catastrophe therefore occurs when the repair error probability exceeds the fraction of deleterious mutations. Our model also gives a quantitative estimate for the equilibrium fraction of mutators in {\it Escherichia coli}.Comment: 4 pages, 2 figures (included as separate PS files

Competition and Predation in Soil Fungivorous Microarthropods Using Stable Isotope Ratio Mass Spectrometry

The soil food web is often described as having three main energy channels: root, bacterial and fungal. Here we provide quantitative data using a sensitive stable isotope ratio mass spectrometry procedure with microcosms on species interactions in the fungal pathway. We measured 15N and 13C enrichment in microarthropods through grazing rare isotope enriched fungal mycelia. Experimental treatments were various combinations of 1, 2, 3, 4 microarthropods species. We used three fungivores (the collembolan Lepidocyrtus curvicollis, the Astigmata Tyrophagus putrescentiae, the Oribatida Oribatula tibialis.), and the Mesostigmata predator Hypoaspis acquilifer We collected individuals of each species separately, as well as their faeces, and moult where available. All three fungivorous microarthropods consumed significantly more than their own body weight per day. The three fungivores differed in their consumption of the mycelium as it was not equally palatable to each. The Mesostigmata predator Hypoaspis also differed in its microarthropod prey preference. In multiple species combinations microarthropod behavioural interactions modified consumption and predation rates. Our selection of mites of different sizes, with varied preference for the mycelium, combined with differing predation rates on each mite, demonstrate that even three trophic level interactions with only five interacting species are not predictably simple. The interpretation of the stable isotope results and consumed-excreted weights indicate that: a) behaviour and microscopic observations should not be ignored in competition-predation interactions, and b) functional guilds can take advantage of more diverse food opportunities. The reality of mixed diets complicates functional guild assignments that are reflected in 15N and 13C isotope levels at natural abundances in the environment. Microcosm experiments with this sensitive technique can help decipher the interpretation of rare isotope natural abundance values, as well as providing measured consumption, growth, and excretion rate values for modelling soil food web interactions

Performances of linseed oil-free bakelite RPC prototypes with cosmic ray muons

A comparative study has been performed on Resistive Plate Chambers (RPC) made of two different grades of bakelite paper laminates, produced and commercially available in India. The chambers, operated in the streamer mode using argon, tetrafluroethane and isobutane in 34:59:7 mixing ratio, are tested for the efficiency and the stability with cosmic rays. A particular grade of bakelite (P-120, NEMA LI-1989 Grade XXX), used for high voltage insulation in humid conditions, was found to give satisfactory performance with stable efficiency of > 96% continuously for more than 130 days. A thin coating of silicone fluid on the inner surfaces of the bakelite RPC is found to be necessary for operation of the detector.Comment: 6 figures, Presented in IX International Workshop on Resistive Plate Chamber and related Detectors-2007, TIFR, Mumbai, India, February 13-16, 200

Polarization Dependent Coupling of Whispering Gallery Modes in Microspheres

Two sets of resonances in glass microspheres attached to a standard communication-grade single-mode optical fiber have been observed. It has been found that the strength of the resonances depends strongly on the polarization of the coupled light. Furthermore, the position of the resonances in the wavelength domain depends on the polarization of light in the optical fiber with maximum magnitudes shifted by approximately 45

Effect of wearing a dorsiflexion assist orthosis on mobility, perceived fatigue and exertion during the six-minute walk test in people with multiple sclerosis: a randomised cross-over protocol

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Background Fatigue in combination with gait and balance impairments can severely limit daily activities in people with multiple sclerosis (PWMS). Generalised fatigue has a major impact on walking ability, with moderately disabled PWMS experiencing difficulty in walking extended distances. Localised motor fatigue in the ankle dorsiflexors can lead to foot drop, further reducing functional ambulation. The aim of this study is to evaluate the effect of a simple dynamic dorsiflexion assist orthosis on walking-induced fatigue, gait, balance and functional mobility in PWMS. Methods A randomised cross-over trial will be conducted with 40 community dwelling PWMS with mild to moderate mobility disability. Participants will initially be screened for disease severity, balance, strength, depression and fatigue at the South Australian Motion Analysis Centre. On two non-consecutive occasions, within two weeks, participants will undergo either the 6-minute walk test (6MWT) or the 6MWT while wearing a dorsiflexion ankle orthosis (with a randomised condition order). Distance walked, perceived exertion, perceived fatigue and the physiological cost of walking (the primary outcome measures) will be compared between the two walking conditions. Additional pre- and post-6MWT assessments for the two conditions will include tests of strength, reaction time, gait and balance. Discussion This study will increase our understanding of motor fatigue on gait and balance control in PWMS and elucidate the effect of a Dynamic Ankle Orthosis on fatigue-related balance and gait in PWMS. It will also examine relationships between mobility and balance performance with perceived fatigue levels in this group

Environmental governance in the Russian Federation: firms and regulator perception of environmental NGOs

Against the backdrop of increasing public awareness of global environmental challenges, this paper examines the potential for collaborative environmental governance in the Russian Federation. To do so, we examine regulators’ and firms’ perceptions of, and collaborations with, environmental non-governmental organizations (eNGOs) in three Russian regions. Our findings highlight that Russian firms rarely collaborateor include eNGOs in environmentally-focused activities because they perceive them to be ineffective, invisible, or irrelevant. Russian regulators do engage with eNGOs, but not as equal partners in the form of collaborative governance arrangements; regulators reduce eNGOs to the positions of subordinates and/or assistants

The hybridisation of Russian non-profit organisations

In this chapter, we look at the impact of the system of ‘managed democracy’ on nonprofit organisations (NPOs) in the Russian Federation and focus on the way in which the lines between them and the agencies of the state have become increasingly blurred. This development is part of the widespread growth in the creation of hybrid organisations on an international scale (Billis, 2010). Hybridity is the result of organisations crossing sectoral boundaries (Pache and Santos, 2013) to form a combination of the characteristics of two or more sectors. One of the more common forms of hybrid organisation blurs the boundaries between NPOs and the state as the former engages in the delivery of public services that had previously been the role of statutory agencies (Billis, 2010). This blurring of sectoral boundaries between NPOs and state is not simply a transfer of practices but involves more fundamental changes to the way organisations operate (Bromley and Meyer, 2017). It means that organisations attempt to adhere to different, if not competing, institutional logics; the ‘rules’ that govern the various sectors (Battilana and Lee, 2014; Brandsen et al., 2005; Doherty et al., 2014; Pache and Santos, 2010). NPOs might, for example, attempt to marry a third sector logic based on collective ownership, engaging constituencies, altruism, provision of free support and/or democratic leadership with a state bureaucracy logic based on centralised control, rule-based mechanisms for service provision and/or hierarchical structures

Restrictive institutions and critical resources : non-profit organisations and volunteer resources in the Russian Federation

Resource management is essential for any organisation’s success. For non-profit organisations (NPOs) volunteers are a key resource. In this article, we examine how NPOs recruit, mobilise and manage volunteers in a challenging institutional and operational context. By drawing on a qualitative study of Russian health NPOs, our study highlights that the operational and institutional environment encountered by Russian NPOs leads to ‘management by network’ to acquire necessary volunteer resources. This pragmatic approach, whilst ensuring an organisation’s short-term survival, ultimately limits the type of volunteer recruited by Russian NPOs. The implications of these findings are also explored

Cosmological mass limits on neutrinos, axions, and other light particles

The small-scale power spectrum of the cosmological matter distribution together with other cosmological data provides a sensitive measure of the hot dark matter fraction, leading to restrictive neutrino mass limits. We extend this argument to generic cases of low-mass thermal relics. We vary the cosmic epoch of thermal decoupling, the radiation content of the universe, and the new particle's spin degrees of freedom. Our treatment covers various scenarios of active plus sterile neutrinos or axion-like particles. For three degenerate massive neutrinos, we reproduce the well-known limit of m_nu < 0.34 eV. In a 3+1 scenario of 3 massless and 1 fully thermalized sterile neutrino we find m_nu < 1.0 eV. Thermally produced QCD axions must obey m_a < 3.0 eV, superseding limits from a direct telescope search, but leaving room for solar eV-mass axions to be discovered by the CAST experiment.Comment: 15 pages, 6 figures, matches version in JCA

Urachal endometrioma: a case report

<p>Abstract</p> <p>Introduction</p> <p>We discuss a rare presentation of an unusual case of endometrioma.</p> <p>Case presentation</p> <p>A 40-year-old Caucasian woman presented with subacute abdominal pain and a suprapubic mass. A final diagnosis was made after the mass was resected and histopathology confirmed an endometrioma originating from an urachal remnant. Select imaging studies and histopathology are presented in this case report.</p> <p>Conclusion</p> <p>While endometriomata are well known to arise from abdominal scars, the condition described in this case report is a rare example of an endometrioma arising from the urachus. A review of the pathological complications of the urachus is also included.</p