Geology of the Atacocha mine, department of Pasco, Peru

The Atacocha lead-zinc mine, 15 km northeast of Cerro de Pasco in Central Peru, was the object of a detailed geologic investigation in 1952 by geologists of the Instituto Nacional de Investigación y Fomento Minero and the U.S. Geological Survey. The mine is about 4,000 m above sea level, in an area of steep topography with about 900 m of relief. Rocks exposed at Atacocha consist of limestone, chert breccia, quartz sandstone, and basalt that range from Late Triassic to Early Cretaceous in age. These rocks have been intruded by dacite of probable Tertiary age. The most prominent structural features are the east limb of a large anticline east of the mine, and a south-plunging syncline to the west. The two folds are separated by a major fault zone. The rocks west of the fault have been dragged along it and are bent into a small cross fold, which seems to be the primary control for the localization of the ore. The main structural feature in the mine is a reverse fault on which limestone has been thrust over quarts sandstone. The Atacocha mine contains about 30 km of underground workings on 16 levels, spaced over a vertical distance of 700 m. The working explores portions of a reverse fault and follow veins in limestone and sandstone. Production was 600 tons of ore per day in late 1953. Ore occurs in veins filling tension fractures in limestone and sandstone near the axis of the cross fold and in irregular replacement bodies in a narrow limestone horizon above and close to the reserve fault. Replacement bodies are also found west of the syncline in limestone close to the contact between limestone and overlying chert breccia. The typical sulfide mineral association is galena, sphalerite, and pyrite, with minor chalcopyrite and jamesonite. Gangue minerals other than pyrite are calcite, rhodochrosite, clay minerals, and a minor amount of fluorite. Late veins of realgar and orpiment cut the ore minerals. Very little oxidation or supergene enrichment has taken place

Formal Design and Analysis for DNA Implementations of Chemical Reaction Networks

In molecular programming, the Chemical Reaction Network model is often used to describe systems of interacting molecules. This model can describe either real systems, allowing us to analyze and determine their computational function; or describe hypothetical systems, with known computational function but perhaps no known physical example. One significant breakthrough in the field is that any Chemical Reaction Network can be approximated by a system using DNA Strand Displacement mechanisms. This allows the Chemical Reaction Network model to be treated like a programming language, where programs can be written in the abstract and then compiled into physical molecules. Given a programming language and a proof-of-concept compiler, one would want to take the compiler from the proof-of-concept stage into a more reliable, more systematic, and better understood process. This thesis is made up of my contributions to that effort. First, given a programming language and a compiler, it would be useful to formally verify that the compiler is correct. My collaborators, Qing Dong and Erik Winfree, and I defined a Chemical Reaction Network-specific form of bisimulation equivalence, which can compare two such networks and verify that one is (or is not) a correct implementation of the other. For example, the compiler-produced DNA circuit can be verified as an implementation of its abstract program, although this is not the only possible use. After defining this concept of equivalence, we show that it can be checked by algorithm; although various parts of the problem are NP-complete or PSPACE-complete, we give algorithms that meet these lower bounds. We also prove a number of interesting properties of Chemical Reaction Network bisimulation equivalence, including transitivity and modularity properties which are particularly useful for stepwise checking of large systems. We further extend this bisimulation method to linear Polymer Reaction Networks, a strictly more powerful abstraction which has been occasionally used in molecular programming. Again we prove complexity hardness results, which in this case are as expected uncomputable in the general case; however, many practical systems can still be verified, and we give one such example. Finally, we use bisimulation to identify a class of single-locus networks that are practical to implement. Thus we show a method of verification which can simplify use of the above-mentioned compiler by proving general statements of correctness about its results. Second, given a programming language and a concept of compiling it, it would be useful to optimize the result of the compilation. One particular area of optimization is the number of DNA strands per prepared complex; some experiments suggest that systems with no more than 2 strands per complex are more robust. Lulu Qian and I developed some proposed DNA Strand Displacement schemes for general Chemical Reaction Network implementations with no more than 2 strands per complex, and a number of other desirable properties. Meanwhile, having been shown to be useful for many reasons, the mechanisms of DNA Strand Displacement have recently been formalized, abstracted, and analyzed. I show that this formalization, combined with the bisimulation methods above, can prove various statements about the limits of DNA Strand Displacement systems. For example, a set of desirable conditions including the 2-strand limit cannot be achieved by any general Chemical Reaction Network implementation scheme. I also observe that two of the new schemes we discovered, each meeting all but one condition of the impossible set, were found in the process of coming up with this proof. I thus argue that through formalization of DNA Strand Displacement we can have a more systematic method of finding and designing molecular programs, and of knowing when the programs we want do not exist.</p

Data-Collection for the Sloan Digital Sky Survey: a Network-Flow Heuristic

The goal of the Sloan Digital Sky Survey is ``to map in detail one-quarter of the entire sky, determining the positions and absolute brightnesses of more than 100 million celestial objects''. The survey will be performed by taking ``snapshots'' through a large telescope. Each snapshot can capture up to 600 objects from a small circle of the sky. This paper describes the design and implementation of the algorithm that is being used to determine the snapshots so as to minimize their number. The problem is NP-hard in general; the algorithm described is a heuristic, based on Lagriangian-relaxation and min-cost network flow. It gets within 5-15% of a naive lower bound, whereas using a ``uniform'' cover only gets within 25-35%.Comment: proceedings version appeared in ACM-SIAM Symposium on Discrete Algorithms (1998

Amino-terminal dimerization of an erythropoietin mimetic peptide results in increased erythropoietic activity

AbstractBackground: Erythropoietin (EPO), the hormone involved in red blood cell production, activates its receptor by binding to the receptor's extracellular domain and presumably dimerizing two receptor monomers to initiate signal transduction. EPO-mimetic peptides, such as EMP1, also bind and activate the receptor by dimerization. These mimetic peptides are not as potent as EPO, however. The crystal structure of the EPO receptor (EBP) bound to EMP1 reveals the formation of a complex consisting of two peptides bound to two receptors, so we sought to improve the biological activity of EPO-mimetic peptides by constructing covalent dimers of EMP1 and other peptide mimetics linked by polyethylene glycol (PEG).Results: The potency of the PEG-dimerized EPO peptide mimetics both in vitro and in vivo was improved up to 1,000-fold compared to the corresponding peptide monomers. The dinners were constructed using peptide monomers which have only one reactive amine per molecule, allowing us to conclude that the increase in potency can be attributed to a structure in which two peptides are linked through their respective amino termini to the difunctional PEG molecule. In addition, an inactive peptide was converted into a weak agonist by PEG-induced dimerization.Conclusions: The potency of previously isolated peptides that are modest agonists of the EPO receptor was dramatically increased by PEG-induced dimerization. The EPO receptor is thought to be dimerized during activation, so our results are consistent with the proposed 2:2 receptor : peptide stoichiometry. The conversion of an inactive peptide into an agonist further supports the idea that dimerization can mediate receptor activation

Mainstreaming domestic and gender-based violence into sociology and the criminology of violence

Sociological and criminological views of domestic and gender-based violencegenerally either dismiss it as not worthy of consideration, or focus on specificgroups of offenders and victims (male youth gangs, partner violence victims). Inthis paper, we take a holistic approach to violence, extending the definition fromthat commonly in use to encompass domestic violence and sexual violence. Weoperationalize that definition by using data from the latest sweep of the CrimeSurvey for England and Wales. By so doing, we identify that violence is currentlyunder-measured and ubiquitous; that it is gendered, and that other forms of violence (family violence, acquaintance violence against women) are equally ofconcern. We argue that violence studies are an important form of activity forsociologists

Steviamine, a new class of indolizidine alkaloid [(1R,2S,3R,5R,8aR)-3-hydroxy­meth­yl-5-methyl­octa­hydro­indolizine-1,2-diol hydro­bromide]

X-ray crystallographic analysis of the title hydro­bromide salt, C10H20N+·Br−, of (1R,2S,3R,5R,8aR)-3-hydroxy­meth­yl-5-methyl­octa­hydro­indolizine-1,2-diol defines the absolute and relative stereochemistry at the five chiral centres in steviamine, a new class of polyhydroxy­lated indolizidine alkaloid isolated from Stevia rebaudiana (Asteraceae) leaves. In the crystal structure, mol­ecules are linked by inter­molecular O—H⋯Br and N—H⋯Br hydrogen bonds, forming double chains around the twofold screw axes along the b-axis direction. Intra­molecular O—H⋯O inter­actions occur

The Student Movement Volume 108 Issue 3: Todos Unidos: Andrews Celebrates Hispanic Heritage Month

HUMANS Hispanic Heritage Month, Grace No Bigger and Better! Hailey and AUSA Coming With New Events for This Year!, Nehemiah Sitler Say Hello to Professor Harris, Grace No Welcome to the Writing Center, Savannah Tyler ARTS & ENTERTAINMENT An Evening with Ada Limón, Nathaniel Miller AU Architecture Program Part I, Katrina Johnson (senior, architecture) Makarios: Hispanic Expression through Ministry, Nailea Soto Stitch by Stitch We Cross-Stitch, Amelia Stefanescu This Semester at HPAC: The Power of Live Music, Reagan McCain NEWS AULA Goes Back-to-School, Melissa Moore International Students Share Thoughts on International Basketball, Andrew Francis Science Complex Hosts Panel on Faith and Science, Andrew Francis Soaked and Destroyed: Hyperactive 2023 Hurricane Season Brings Destruction to East Coast., Nehemiah Sitler IDEAS A Brief Understanding of the Venezuelan Refugee Crisis, Robert Zhang Do You Want to Get Starbucks Right Now? , Charisse Lapuebla Fentanyl: From Pain Relief to Public Health Crisis, Katherine Pierre PULSE A Conscious Community, Caitlin Adap Spiritual Life at AU, Rodney Bell II Voy a Palenque, Wambi Karanja LAST WORD Multipassionate Potential, Melissa Moorehttps://digitalcommons.andrews.edu/sm-108/1002/thumbnail.jp