Towards a complete accounting of energy and momentum from stellar feedback in galaxy formation simulations

Stellar feedback plays a key role in galaxy formation by regulating star formation, driving interstellar turbulence and generating galactic scale outflows. Although modern simulations of galaxy formation can resolve scales of 10-100 pc, star formation and feedback operate on smaller, "subgrid" scales. Great care should therefore be taken in order to properly account for the effect of feedback on global galaxy evolution. We investigate the momentum and energy budget of feedback during different stages of stellar evolution, and study its impact on the interstellar medium using simulations of local star forming regions and galactic disks at the resolution affordable in modern cosmological zoom-in simulations. In particular, we present a novel subgrid model for the momentum injection due to radiation pressure and stellar winds from massive stars during early, pre-supernova evolutionary stages of young star clusters. Early injection of momentum acts to clear out dense gas in star forming regions, hence limiting star formation. The reduced gas density mitigates radiative losses of thermal feedback energy from subsequent supernova explosions, leading to an increased overall efficiency of stellar feedback. The detailed impact of stellar feedback depends sensitively on the implementation and choice of parameters. Somewhat encouragingly, we find that implementations in which feedback is efficient lead to approximate self-regulation of global star formation efficiency. We compare simulation results using our feedback implementation to other phenomenological feedback methods, where thermal feedback energy is allowed to dissipate over time scales longer than the formal gas cooling time. We find that simulations with maximal momentum injection suppress star formation to a similar degree as is found in simulations adopting adiabatic thermal feedback.Comment: ApJ submitted. For a high-resolution version of the paper, see http://kicp.uchicago.edu/~agertz

Solid Waste Challenges and Management in a Traditional Sahelian City: A Case Study of Sokoto, Nigeria

This study assessed the solid waste generation, management, and consequences in the traditional city of Sokoto. The utmost challenges facing this Sahel region include scarcity of modernized and control measures of waste resulting from daily hectic impacts on the community. In this city, solid waste is characterized by inefficient control, insufficient coverage of collection system and improper disposal methods. The increasing population of residents has accelerated more pollution of all categories, and the consequence is a dearth of hygienic standards. This work further sampled different materials from heaps of waste such as; the level of sub-soils at 0-30 cm (at random) from each of the dump sites to determine the extent of heavy metal concentrations and for fertility supplement in comparison with the National Environmental Standards and Regulations Enforcement Agency (NESREA). Fifty structural questionnaires were administered randomly to selected residents around dumping sites and the staff of Sokoto Waste Management &Planning Board to solicit relevant information that can assist the governments, stakeholders, and waste control agencies. Also, Landsat data was utilized to map out the waste sites for spatio-temporal analysis. Results indicated that 89% of respondents agreed that Sokoto metropolis is characterized by untidiness with masquerades of biodegradable wastes, while major streets especially in the congested areas which displayed a lot of drains and channels remain blocked. DOI: http://doi.org/10.31357/fhss/vjhss.v09i01.0

Descent Relations and Oscillator Level Truncation Method

We reexamine the oscillator level truncation method in the bosonic String Field Theory (SFT) by calculation the descent relation =Z_3<V_2|. For the ghost sector we use the fermionic vertices in the standard oscillator basis. We propose two new schemes for calculations. In the first one we assume that the insertion satisfies the overlap equation for the vertices and in the second one we use the direct calculations. In both schemes we get the correct structures of the exponent and pre-exponent of the vertex <V_2|, but we find out different normalization factors Z_3.Comment: 21 pages, 10 figures, Late

The Geometric Phase and Ray Space Isometries

We study the behaviour of the geometric phase under isometries of the ray space. This leads to a better understanding of a theorem first proved by Wigner: isometries of the ray space can always be realised as projections of unitary or anti-unitary transformations on the Hilbert space. We suggest that the construction involved in Wigner's proof is best viewed as an use of the Pancharatnam connection to ``lift'' a ray space isometry to the Hilbert space.Comment: 17 pages, Latex file, no figures, To appear in Pramana J. Phy

A Double-Edged Sword Role for Ubiquitin-Proteasome System in Brain Stem Cardiovascular Regulation During Experimental Brain Death

BACKGROUND: Brain stem cardiovascular regulatory dysfunction during brain death is underpinned by an upregulation of nitric oxide synthase II (NOS II) in rostral ventrolateral medulla (RVLM), the origin of a life-and-death signal detected from blood pressure of comatose patients that disappears before brain death ensues. Furthermore, the ubiquitin-proteasome system (UPS) may be involved in the synthesis and degradation of NOS II. We assessed the hypothesis that the UPS participates in brain stem cardiovascular regulation during brain death by engaging in both synthesis and degradation of NOS II in RVLM. METHODOLOGY/PRINCIPAL FINDINGS: In a clinically relevant experimental model of brain death using Sprague-Dawley rats, pretreatment by microinjection into the bilateral RVLM of proteasome inhibitors (lactacystin or proteasome inhibitor II) antagonized the hypotension and reduction in the life-and-death signal elicited by intravenous administration of Escherichia coli lipopolysaccharide (LPS). On the other hand, pretreatment with an inhibitor of ubiquitin-recycling (ubiquitin aldehyde) or ubiquitin C-terminal hydrolase isozyme L1 (UCH-L1) potentiated the elicited hypotension and blunted the prevalence of the life-and-death signal. Real-time polymerase chain reaction, Western blot, electrophoresis mobility shift assay, chromatin immunoprecipitation and co-immunoprecipitation experiments further showed that the proteasome inhibitors antagonized the augmented nuclear presence of NF-κB or binding between NF-κB and nos II promoter and blunted the reduced cytosolic presence of phosphorylated IκB. The already impeded NOS II protein expression by proteasome inhibitor II was further reduced after gene-knockdown of NF-κB in RVLM. In animals pretreated with UCH-L1 inhibitor and died before significant increase in nos II mRNA occurred, NOS II protein expression in RVLM was considerably elevated. CONCLUSIONS/SIGNIFICANCE: We conclude that UPS participates in the defunct and maintained brain stem cardiovascular regulation during experimental brain death by engaging in both synthesis and degradation of NOS II at RVLM. Our results provide information on new therapeutic initiatives against this fatal eventuality

Bargmann invariants and off-diagonal geometric phases for multi-level quantum systems -- a unitary group approach

We investigate the geometric phases and the Bargmann invariants associated with a multi-level quantum systems. In particular, we show that a full set of `gauge-invariant' objects for an $n$-level system consists of $n$ geometric phases and ${1/2}(n-1)(n-2)$ algebraically independent 4-vertex Bargmann invariants. In the process of establishing this result we develop a canonical form for U(n) matrices which is useful in its own right. We show that the recently discovered `off-diagonal' geometric phases [N. Manini and F. Pistolesi, Phys. Rev. Lett. 8, 3067 (2000)] can be completely analysed in terms of the basic building blocks developed in this work. This result liberates the off-diagonal phases from the assumption of adiabaticity used in arriving at them.Comment: 13 pages, latex, no figure

Analyses of the Leaf, Fruit and Seed of Thaumatococcus tktniellii (Benth.): Exploring Potential Uses

Thaumatococcus daniellii is an economic plant with versatile uses in Southern Nigeria. The arils attached to the seeds contain thawnatin, a non-sugar sweetener and taste modifier. This study examined the chemical constituents of the leaf, fruit and seed ofT. daniellii. The fresh fruit, on weight basis, consists of 4.8% aril, 22.8% seed and 72.4% fleshy part The leaf contained (per 100 g): 10.67 g moisture, 8.95 gash, 17.21 g fat, 21.06 g protein, 24.61 g crude fiber 17.50 g carbohydrate, 0.10 g calcium, 0.08 g magnesium, 0.01 g iron and 0.37 g phosphorus. The fruit (fleshy part) contained 10.04 g moisture, 21.08 gash, 0.93 g fat 11.53 g protein, 18.43 g crude fiber, 37.27 g carbohydrate, 0.34 g calcium, 0.30 g magnesium, 0.01 g iron and 0.21 g phosphorus. The seed contained 15.15 g moisture, 11.30 g ash, 0.21 g fat, 10.36 g protein, 20.52 g crude fiber and 42.46 g carbohydrate. Terpenoids, flavonoids, alkaloids and cardiac glycosoides were significantly present in both the leaf and fruit whereas phlobatani:n, saponin, steroids, anthraquinones and ascorbic acid were absent. Tannin was present only in the leaf. The leaf and fruit ofT. daniellii have significant nutritional and medicinal benefits. The leaf is rich in protein and fat. The fruit is a good source of minerals, particularly, calciwn and magnesiwn; the leaf is also rich in phosphoru

Elasticity of semiflexible polymers with and without self-interactions

A {\it new} formula for the force vs extension relation is derived from the discrete version of the so called {\it worm like chain} model. This formula correctly fits some recent experimental data on polymer stretching and some numerical simulations with pairwise repulsive potentials. For a more realistic Lennard-Jones potential the agreement with simulations is found to be good when the temperature is above the $\theta$ temperature. For lower temperatures a plateau emerges, as predicted by some recent experimental and theoretical results, and our formula gives good results only in the high force regime. We briefly discuss how other kinds of self-interactions are expected to affect the elasticity of the polymer.Comment: 8 pages, 10 figure

Analyses of the Leaf, Fruit and Seed of Thaumatococcus tktniellii (Benth.): Exploring Potential Uses

Thaumatococcus daniellii is an economic plant with versatile uses in Southern Nigeria. The arils attached to the seeds contain thawnatin, a non-sugar sweetener and taste modifier. This study examined the chemical constituents of the leaf, fruit and seed ofT. daniellii. The fresh fruit, on weight basis, consists of 4.8% aril, 22.8% seed and 72.4% fleshy part The leaf contained (per 100 g): 10.67 g moisture, 8.95 gash, 17.21 g fat, 21.06 g protein, 24.61 g crude fiber 17.50 g carbohydrate, 0.10 g calcium, 0.08 g magnesium, 0.01 g iron and 0.37 g phosphorus. The fruit (fleshy part) contained 10.04 g moisture, 21.08 gash, 0.93 g fat 11.53 g protein, 18.43 g crude fiber, 37.27 g carbohydrate, 0.34 g calcium, 0.30 g magnesium, 0.01 g iron and 0.21 g phosphorus. The seed contained 15.15 g moisture, 11.30 g ash, 0.21 g fat, 10.36 g protein, 20.52 g crude fiber and 42.46 g carbohydrate. Terpenoids, flavonoids, alkaloids and cardiac glycosoides were significantly present in both the leaf and fruit whereas phlobatani:n, saponin, steroids, anthraquinones and ascorbic acid were absent. Tannin was present only in the leaf. The leaf and fruit ofT. daniellii have significant nutritional and medicinal benefits. The leaf is rich in protein and fat. The fruit is a good source of minerals, particularly, calciwn and magnesiwn; the leaf is also rich in phosphoru

Superalgebra and Conservative Quantities in N=1 Self-dual Supergravity

The N=1 self-dual supergravity has SL(2,C) and the left-handed and right -handed local supersymmetries. These symmetries result in SU(2) charges as the angular-momentum and the supercharges. The model possesses also the invariance under the general translation transforms and this invariance leads to the energy-momentum. All the definitions are generally covariant . As the SU(2) charges and the energy-momentum we obtained previously constituting the 3-Poincare algebra in the Ashtekar's complex gravity, the SU(2) charges, the supercharges and the energy-momentum here also restore the super-Poincare algebra, and this serves to support the reasonableness of their interpretations.Comment: 18 pages, Latex, no figure