Bi-Marcus? The two Varrones of Augustine and Nonius Marcellus

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Varro, Atticus and Annales

This paper explores the scholarly relationship between Varro and Atticus by focusing on the attribution of a Varronian fragment (Gell. 17.21.24). Taking into account Gellius's citation practices, it is argued that the fragment (concerning the execution of the tyrant Manlius) was mediated via Atticus, not taken directly from Varro. The evidence for Varro's and Atticus's friendship and scholarly cooperation undermines traditional attempts to identify any ultimate written source for this material, and prompts a re-evaluation of the relationship between the two friends’ antiquarian interests to outline the consequences of scholarly and social exchange. This investigation suggests that, like many apparent points of Attico-Varronian overlap (including Rome's foundation-date), the fragment's origins might owe more to personal acquaintance than secluded book-learning. Their antiquarian choices had the potential to be politically charged, and the version of Manlius's death endorsed by Varro may thus indicate his political stance towards Caesar

Developing a low cost solar powered water pump for deployment in developing nations for agricultural purposes

Developing a low cost solar powered water pump for deployment in developing nations for agricultural purpose

DNA sequencing with MspA: molecular dynamics simulations reveal free-energy differences between sequencing and non-sequencing mutants

MspA has been identified as a promising candidate protein as a component of a nanopore-based DNA-sequencing device. However the wildtype protein must be engineered to incorporate all of the features desirable for an accurate and efficient device. In the present study we have utilized atomistic molecular dynamics to perform umbrella-sampling calculations to calculate the potential of mean force (PMF) profiles for translocation of the four DNA nucleotides through MspA. We show there is an energetic barrier to translocation of individual nucleotides through a mutant that closely resembles the wildtype protein, but not through a mutant engineered for the purpose of sequencing. Crucially we are able to quantify the change in free energy for mutating key residues. Thus providing a quantitative characterisation of the energetic impact of individual amino acid sidechains on nucleotide translocation through the pore of MspA

Another face of Lorenz-Mie scattering: monodisperse distributions of spheres produce Lissajous-like patterns

The complete scattering matrix S of spheres was measured with a flow cytometer. The experimental equipment allows simultaneous detection of two scattering-matrix elements for every sphere in the distribution. Two-parameter scatterplots withx andy coordinates determined by the Sll + Sij and S11 - Sij values are measured. Samples of spheres with very narrow size distributions (< 1%) were analyzed with a FlowCytometer, and they produced unexpected two-parameter scatterplots. Instead of compact distributions we observed Lissajous-like loops. Simulation of the scatterplots, using Lorenz-Mie theory, shows that these loops are due not to experimental errors but to true Lorenz-Mie scattering. It is shown that the loops originate from the sensitivity of the scattered field on the radius of the spheres. This paper demonstrates that the interpretation of rare events and hidden features in flow cytometry needs reconsideration

Scheduling train crews: a case study for the Dutch Railways

In this paper the problem of scheduling train crew is considered. We discuss a general framework of which the method for solving the train crew scheduling problem is a special case. In particular, our method is a heuristic branch-and-price algorithm suitable for large scale crew scheduling problems. This algorithm is applied to a real life train guard scheduling problem which is provided to us by the Dutch Railways. Computational results show that our algorithm is capable of getting sub-optimal solutions for a large scale instance within reasonable computation time

The f-vector of the descent polytope

For a positive integer n and a subset S of [n-1], the descent polytope DP_S is the set of points x_1, ..., x_n in the n-dimensional unit cube [0,1]^n such that x_i >= x_{i+1} for i in S and x_i <= x_{i+1} otherwise. First, we express the f-vector of DP_S as a sum over all subsets of [n-1]. Second, we use certain factorizations of the associated word over a two-letter alphabet to describe the f-vector. We show that the f-vector is maximized when the set S is the alternating set {1,3,5, ...}. We derive a generating function for the f-polynomial F_S(t) of DP_S, written as a formal power series in two non-commuting variables with coefficients in Z[t]. We also obtain the generating function for the Ehrhart polynomials of the descent polytopes.Comment: 14 pages; to appear in Discrete & Computational Geometr

Soil nitrogen storage and availability to crops are increased by conservation agriculture practices in rice - based cropping systems in the Eastern Gangetic Plains

On-farm adoption of minimum soil disturbance and increased residue retention will alter nitrogen (N) dynamics in soils and N fertiliser management in the intensive rice–based triple cropping systems of the Eastern Gangetic Plains. However, the consequences of changes in N forms, N mineralisation and its availability for crops have not been determined. Field experiments were conducted at two locations (Alipur and Digram) of north–west Bangladesh (NWB) to examine N cycling under three planting practices (conventional tillage (CT), strip planting (SP) and bed planting (BP)) with increased (HR) or low residue retention (LR– the current practice) on Calcareous Brown Flood Plain and Grey Terrace soils. Total N and available N were measured on soil samples as was N uptake by crops at different growth stages in the 13–14th (Alipur) and 12–13th (Digram) crops since treatments commenced. At each location (0–10 cm soil depth), SP, including non–puddled transplanting of rice seedlings (NP), together with HR increased total N by 9 and 32 % relative to BPHR, and CTHR and by 62 % relative to the current farm practice (CTLR). In general, the cumulative available N in soils during mustard and rice cropping under CT with HR was higher than other crop establishment and residue retention practices while under wheat and jute, total availability of N did not vary among crop establishment types with increased residue retention. Nitrogen availability in the initial phase of crop growth (0–60 DAS) was generally higher with CT than SP and BP. By contrast, for all crops, the estimated potentially mineralisable N was higher and its decay rate was lower under SPHR than other crop establishment and residue retention practices. Conservation Agriculture practices (SP, and NP of rice, together with HR) have altered the N cycling by reducing the level of mineral N available to plants in the early growing season when crop demand is low, but by increasing soil total N (0−10 cm) and plant N uptake which enhanced the synchrony between crop demand and available N supply

Transport processes during electrowashing of filter cakes

Applications of electric fields during washing of filter cakes increases the removal rate of ions from the cake mother liquor, and under appropriate conditions the field also increases the wash flow rate by electroosmosis. Experimental data that show the key effects of the fields on the rates of ion mass transfer are presented: with the downstream electrode acting as a cathode, cation removal rates are increased whilst the removal rate of the anions is decreased. The concentration profile of the cations with washing time shows an increase in concentration to a value above that of the mother liquor, before it decreases due to displacement by the fresh wash liquor. A model is formulated that describes the advection, dispersion, ion migration and electroosmosis transport processes in the cake. Numerical solution of the model gives cation concentration profiles at the exit of the cake that are in qualitative agreement with the experimental observations. Experimentally measured wash liquor flow rates tend to be lower than what traditional colloid science principles predict by a factor of 5 to 10: reasons for this difference, supported by experimental work from other researchers, are discussed

Electrically enhanced removal of solutes from filter cakes - interpretation of peak mass transfer rates

Some results from an experimental and theoretical investigation of cake washing assisted by d.c. electrical fields are reported. Electric fields are shown to increase the rate of removal of cations (Na+) from rutile filter cakes when the downstream electrode was the cathode. For anions (NO3 -) under the same experimental conditions, the removal rate also varied with the electric field but the effect was to slow the rate of mass transfer. To give initial insight into the observed phenomena, the effects are explained through a first order model. The basic assumptions of the model are that: (1) there are two external forces driving the transport of ions: (i) a pressure difference that causes a mean fluid flow in which the ions are embedded, and (ii) the DC electric field applied across the cake; and (2) there are two pools of ions: (i) those trapped in the pores, and (ii) those that move with either the main fluid flow or the electrically generated ionic current. The model demonstrates the same qualitative effects as seen in the experiments, with the magnitude of the effects dependent on the magnitudes of lateral and axial ion flux component constitutive forms