Modelling of Mouse Spermatogonial Stem Cell Niche for Designing 3D scaffolds for in vitro Spermatogenesis

The homeostasis of male genitalia in mammals is maintained by a group of stem cells called spermatogonial stem cells (SSCs) which replenishes worn out cells in the testicular tissue. In mouse, these cells are housed by specialised tubular structures called seminiferous tubules. The SSC niche is found dispersed on the basal lamina, which is a two dimensional extracellular matrix along the circumference of seminiferous tubules. The Myoid, Sertoli and Leydig cells support SSCs while self-renewal and differentiation. The self-renewal and migration of SSCs takes place along the lateral direction and differentiation occurs medially towards the lumen of seminiferous tubules. The differentiation and self-renewal occurs in a cycle with each cycle possessing 12 stages of seminiferous epithelium. The self-renewal and commitment for differentiation of stem cells occurs from stages X – VIII of seminiferous epithelium. A MatlabTM program was developed to simulate the behavior of SSCs in their niche within the seminiferous tubules with logical rules. The migration, self-renewal and differentiation of SSCs was modelled according to the logical parameters provided by researches over the past century. The behavior of SSCs in their niche was assumed to be dependent on cell density in that niche area. The SSCs responded to the density stress imposed on them by their neighbouring cells which forced them migrate into a space with lower stress. Similarly, division and differentiation was also controlled by density stress through various thresholds. The model outcome was validated with literature. The model predicted that there was 12 Asingle cells, 15 Apaired cells and 19 Aaligned cells per 1000 Sertoli cells in the niche of mouse. With these metrics in concern, a biopolymer scaffold was prepared by using alginate to mimic the testicular tissue. Polymerisation was performed by the process of ionotropic gelation with CaCl2 as the crosslinker. Channels of diameter from 100 μm to 250 μmm were obtained in the anisotropic gel. The tubular nature of the scaffold mimicked seminiferous tubules in dimension. Physiochemical characterization like SEM, FTIR, Mechanical analysis of the scaffold was done on the scaffold

A new concept for the water supply at CERN

The present state of the station Le Vengeron (the main pumping station supplying CERN with drinking water), and also to comply with the new Swiss standards impose a thorough consolidation and upgrade of this station which is shared with the Services Industriels de Genève (SIG). The total cost of the works (around 62 MCHF) would be shared proportionally to the nominal flow-rate demand which, at present, is of 2/3 for CERN and 1/3 for SIG. An alternative to the above is a complete review of CERN's water consumption, reducing our needs by half, thus allowing savings in both investment and operation. This reduction in investment cost would be diverted towards much needed consolidation works for the existing facilities within CERN. This paper also reviews the planning and possible ways for the execution of the works and the future responsibilities of operation of the water distribution systems (drinking and machine) inside CERN's sites

ST-ATLAS infrastructure coordination

The ST division launched a collaboration programme with the LHC (experiments and machine) management, by appointing the so-called ST coordinators. The role of the coordinator is to smooth out the relationships amongst representatives of the infrastructure groups, not exclusively within the ST division. This role is nevertheless bound to change as the project unfolds into its different phases. For the time being though, the coordinator's task is to centralize all requests for information from, and provide support to, the collaboration. In the case of ATLAS, the first months of this collaboration have already given some good results, which will be reported in this and future papers. The present paper is to be understood as a progress report summarizing the main items which have been dealt with up to now

Smoke control and "Désenfumage" systems

The intention of this technical note is to explain what a smoke control (SC) system is, and to what extent SC systems (and derivatives) are used at CERN. The role of ST Division in relation to these systems will be analysed, and some improvements suggested. This note is particularly addressed to people with local safety responsibility (TSO, DSO, etc.) but it also might be of interest to the CERN user in general. The complete list of facilities, under the responsibility of ST, having any relation with the control of smoke can be found at the end of the note

The LHC experiments as seen from the Technical Sector

Since the beginning of the collaboration between the ST division and the LHC experiments, already in 1998, the technical sector has provided different structures for the support of the experiments, aiming to coordinate all the activities, which traditionally belong in the technical sector's mandate, like civil engineering and structures, cooling and ventilation, cranes and transport, electricity, gas, etc. A picture of the last year's activity, mainly concentrated on the ATLAS and CMS experiments, shows how the synergies between project managers, staff involved and group structures can strongly improve the service level in the technical domain. This closer collaboration has facilitated the development of further ties linked to the competence available in the groups, and of great interest to the experiments. The steady rise in demand confirms that the choice, made by the experiments, confirms that the technical sector support is a real need in this are

Performance of Chirp-Slope Keying with Joint Time-Frequency Detectors

This paper discusses recent studies on Chirp Slope Keying (CSK) as a scheme suitable for underwater communications and presents a new study on the performance of a time-frequency receiver in a Rayleigh fading environment. As expected, CSK proves to be a digital modulation scheme inferior in the AWGN channel as compared to traditional schemes but very promising in more detrimental channels present in underwater communications. In effect, while most schemes’ performances decay abruptly with the addition of new disturbances, a time-frequency CSK receiver’s performance deteriorates slowly with increasing Rayleigh fading. Intuition dictates that CSK will overpower other schemes as channel conditions continue to worsen. The receiver first uses the Wigner distribution to transform the incoming signal to the joint time-frequency domain and then computes the Radon transform to determine the binary digit received

Scattering of entropy waves into sound by isolated aerofoils

This article presents a modelling approach to predict the low-frequency sound generated by entropy fluctuations interacting with isolated aerofoils. A model of the acoustic field is obtained based on a linearisation of the compressible Euler equations about a steady, potential, compressible mean flow. Mean flow variations of velocity and density are accounted for in the source term, but are neglected in the sound propagation. Using a Lorentz-type transformation, the problem is reduced to solving a Helmholtz equation. This equation is recast in integral form and a solution is obtained using a compact Green's function method. This approach places no restrictions on the entropy wavelength, while assuming that the acoustic wavelength is large compared to the profile chord and spacing. The source term is further simplified by assuming that the steady flow is a small perturbation to a uniform flow. The model is illustrated using a symmetric aerofoil and its performance is assessed against numerical simulations of the compressible Euler equations. Good agreement is found for all the frequencies of validity of the theory and for all the range of subsonic Mach numbers. The solution for a symmetric aerofoil interacting with plane entropy waves corresponds to the combination of a dipole along the horizontal axis and a monopole. The dipole originates from the unsteady drag experienced by the aerofoil owing to the fluctuations of density and the monopole from the strong local acceleration of the flow at the leading edge. The monopole term becomes negligible for low Mach numbers

Review of morphology dependent charge carrier mobility in MEH-PPV

Charge carrier mobility in poly(2-methoxy,5(2'-ethyl-hexyloxy)-p-phenylene vinylene) (MEH-PPV) films were measured as a function of temperature and electric field parallel and perpendicular to the substrate for devices prepared from different solvents and under different processing conditions Bulk structural morphology was characterized by various X-ray diffraction measurements such as wide angle, small angle and X-ray reflection. Surface morphology was characterized using various scanning probe microscopic techniques Mobilities were found to follow Gaussian disorder model (GDM) and to be highly anisotropic not only depending on the solvents used but also on the film preparation method such as spin-coating or drop-casting While no direct correlation was found between charge carrier mobility and photoluminescence, charge transport parameters were correlated with structural morpholog

A discursive psychology analysis of emotional support for men with colorectal cancer

Recent research into both masculinity and health, and the provision of social support for people with cancer has focussed upon the variations that may underlie broad assumptions about masculine health behaviour. The research reported here pursues this interest in variation by addressing the discursive properties of talk about emotional support, by men with colorectal cancer - an understudied group in the social support and cancer literature. Semi-structured interviews were conducted with eight men with colorectal cancer, and the transcripts analysed using an intensive discursive psychology approach. From this analysis two contrasting approaches to this group of men’s framing of emotional support in the context of cancer are described. First, talk about cancer was positioned as incompatible with preferred masculine identities. Second, social contact that affirms personal relationships was given value, subject to constraints arising from discourses concerning appropriate emotional expression. These results are discussed with reference to both the extant research literature on masculinity and health, and their clinical implications, particularly the advice on social support given to older male cancer patients, their families and friends

The effect of group size and individual characteristics on between-group encounters in primates

Between-group encounters are common in non-human primates and can vary from affiliative to aggressive. We extracted data from the literature to test five different hypotheses: 1) where there are group size differences between opposing groups, whether the larger group is more likely to win a between-group encounter than the smaller group; 2) whether the likelihood of a group engaging in aggressive between-group encounters increases with group size; and 3-5) whether dominant, older animals, and/or males are more likely to participate aggressively in between-group encounters than subordinate, younger animals and/or females. Our dataset comprised 52 studies on 31 primate species (3 lemur species, 5 New World monkeys, 19 Old World monkeys and 4 apes). We found that the larger group is more likely to win an encounter against a smaller group than vice-versa. We found no significant relationship between group size and propensity to be aggressive during between-group encounters. We found weak/no support for the effect of age, dominance rank and sex on the frequency of aggression displayed towards outgroup animals during between-group encounters. Species- and population-specific differences in between- and within-group competition and in the degree of the unequal distribution of resources across group members may explain why age, dominance rank and sex are not strong predictors of aggression during between-group encounters