Of Time and Tense: An Analysis of the English Verb Tense System for the ESL Teacher

The intent of the writer with this paper is to provide the ESL instructor with the knowledge necessary to effective planning for and teaching of lessons concerning the verb tenses of English. The analysis given in the paper is an attempt at viewing the verb tenses as compromising a system which is basically symmetrical and surprisingly logical. As such, it is felt that through exploring the relationships tenses share with one another, we have found the key to demonstrating tense usage and meaning effectively for students and to planning drills and exercises which will zero in on the primary conceptual distinctions among the tenses. Where one tense is, in form or meaning, analogous to another tense in another time frame, we can exploit that relationship to reinforce learning of both tenses. By the same token, where conceptual disctinctions between two tenses are subtle and a potential cause of learning interference, we can separate out the territory of each far better by viewing them in contrast to one another than by presenting and practicing each of them in isolation. The writer deals with both form and meaning of a tense and hypothesizes that each tense form has a primary meaning and each tense meaning a primary form. Tense form is often changed due to limiting surface structure requirements in the language. For example, use of a modal inhibits a Past tense meaning from surfacing in a Past tense form; it must instead take a Present Perfect form. At the same time, tense forms are called on to express secondary time-reference meanings. For example, Present Simple can be used, in addition to its more prominent use of expressing Present habit, as means of expressing future scheduled time, a concept more primarily associated with one of the Future (will or be going to ) tenses. Here the writer recommends that instructors and students play Percentage English . If this secondary usage is of relative unimportance and /or the concept can be expressed just as well with a more primary form and/or use of this secondary form can lead to interference in the student\u27s ability to internalize basic tense usage, the writer feels it should be taught for recognition value at most and that students should be discouraged from producing it until they have mastered use of the basic system of tenses

Contaminants in Chesapeake Bay: The Regional Perspective

Industrial and municipal point sources of contaminants are scattered along the shores of Chesapeake Bay and its tributaries, but reach especially high density at Norfolk, Va., and Baltimore, Md. Sedimentation and various chemical processes in many cases conspire to restrict the water-borne transport of contaminant away from point source . Kepone, residual chlorine, volatile halogenated hydrocarbons, and anthropogenic trace metals are well-studied example of point-source contaminants. For the most part, their concentration in water and sediment drop to nearly immeasurable values within a distance of a few kilometers, or sometimes a few tens of kilometers, from their source . On the other hand, certain contaminants have now been shown to be truly regionally dispersed. Included are polychlorinated biphenyls, phthalate esters, anthropogenic trace metal (Cu, Zn, Pb), polycyclic aromatic hydrocarbons, herbicides and weapon derived radionuclides. Most of these enter the Bay in significant amount from the atmosphere. Thus their dispersion throughout the Bay is not dependent on aquatic tranport processes. Although it is tempting to link the existence of this regional contamination with well publicized regional biological problem , no link has yet been proven.https://scholarworks.wm.edu/vimsbooks/1058/thumbnail.jp

Toward an understanding of disequilibrium dihedral angles in mafic rocks

[1] The median dihedral angle at clinopyroxene-plagioclase-plagioclase junctions in mafic rocks, Θcpp, is generally lower than equilibrium (109° ± 2°). Observation of a wide range of mafic bodies demonstrates that previous work on systematic variations of Θcpp is incorrect in several important respects. First, the spatial distribution of plagioclase compositional zoning demonstrates that the final geometry of three-grain junctions, and hence Θcpp, is formed during solidification (the igneous process): sub-solidus textural modification in most dolerites and gabbros, previously thought to be the dominant control on Θcpp, is insignificant. Θcpp is governed by mass transport constraints, the inhibiting effects of small pore size on crystallization, and variation in relative growth rates of pyroxene and plagioclase. During rapid cooling, pyroxene preferentially fills wider pores while the narrower pores remain melt-filled, resulting in an initial value of Θcpp of 78°, rather than 60° which would be expected if all melt-filled pores were filled with pyroxene. Lower cooling rates create a higher initial Θcpp due to changes in relative growth rates of the two minerals at the nascent three-grain junction. Low Θcpp (associated with cuspate clinopyroxene grains at triple junctions) can also be diagnostic of infiltration of previously melt-free rocks by late-stage evolved liquids (the metasomatic process). Modification of Θcpp by sub-solidus textural equilibration (the metamorphic process) is only important for fine-grained mafic rocks such as chilled margins and intraplutonic chill zones. In coarse-grained gabbros from shallow crustal intrusions the metamorphic process occurs only in the centers of oikocrysts, associated with rounding of chadacrysts

A report on the concentration, distribution and impact of certain trace metals from sewage treatment plants on the Chesapeake Bay

Population densities are ever increasing on the shores of the Chesapeake Bay and hence the flow of goods and services is being shifted to supply these people. This self perpetuating system demanismore and more of the surrounding envirorunent f or recreation, work and waste disposal. This is the case f or the Chesapeake and its sub- estuaries. According to Brush (1974), of the total fresh water input into the Chesapeake Bay, between 1 and 2 percent is treated sewage. Toxic components on these waters may be of paramount importance in the Bay ecosystem and ma;y have disastrous effects on the biota. It is essential then that the magnitude of the exist ing problem be determined and understood, and results and recommendations be made available to decision makers so that in the future we can control the inputs, properly select sewage outfall locations and preserve the Chesapeake Bey for future generations . This document is a first attempt at this

Nuclear Reactor Safeguarding with Neutrino Detection for MOX Loading Verification

The resurgence of interest in nuclear power around the world highlights the importance of effective methods to safeguard against nuclear proliferation. Many powerful safeguarding techniques have been developed and are currently employed, but new approaches are needed to address proliferation challenges from emerging advanced reactor designs and fuel cycles. Building on prior work that demonstrated monitoring of nuclear reactor operation using neutrino detectors, we develop and present a simple quantitative statistical test suitable for analysis of measured reactor neutrino data and demonstrate its efficacy in a semi-cooperative reactor monitoring scenario. In this approach, a moderate-sized neutrino detector is placed near the reactor site to help monitor possible MOX fuel diversion independent of inspection-based monitoring. We take advantage of differing time-dependent neutrino count rates during the operating cycle of a reactor core to monitor any deviations of measurements from expectations given a declared fuel composition. For a five-ton idealized detector placed 25m away from a hypothetical 3565 MWth reactor, the statistical test is capable of detecting the diversion of ~80kg plutonium at the 95% confidence level 90% of the time over a 540-day observation period.Comment: 35 pages, 24 figure

A Patient with Aids

Susan Ball , M.D.. Chief Resident: Mr. B, a thirty-five-year-old white male, was admitted to the medical service with chief complaints of fever, chills, and increasing shortness of breath. This was Mr. B\u27s second admission. His first was six month s ago for pneumonia, leukopenia, and lymphadenopathy of unknown etiology. At that time he was treated with antibiotics; he improved and was discharged. Since that time Mr. B reported continuing to feel weak and lethargic. Two weeks before this admission he noted the onset of fever, chills, sore throat, and a nonproductive cough. He initially saw a medical doctor for these complaints who diagnosed his problem as bronchitis and treated him with intramuscular injections that were probably antibiotic in nature. He continued to experience malaise and fever. Next he saw an otolaryngologist, who diagnosed Mr . B as having oral thrush. He was placed on Mycostatin Oral Suspensions , but continued to experience increasing fever, chills, shortness of breath , and sore throat, as well as a rthralgias, abdominal pain, and diar rhea. Shortly thereafter Mr. B was admitted to the hospital

Compositional boundary layers trigger liquid unmixing in a basaltic crystal mush

Abstract: The separation of immiscible liquids has significant implications for magma evolution and the formation of magmatic ore deposits. We combine high-resolution imaging and electron probe microanalysis with the first use of atom probe tomography on tholeiitic basaltic glass from Hawaii, the Snake River Plain, and Iceland, to investigate the onset of unmixing of basaltic liquids into Fe-rich and Si-rich conjugates. We examine the relationships between unmixing and crystal growth, and the evolution of a nanoemulsion in a crystal mush. We identify the previously unrecognised role played by compositional boundary layers in promoting unmixing around growing crystals at melt-crystal interfaces. Our findings have important implications for the formation of immiscible liquid in a crystal mush, the interpretations of compositional zoning in crystals, and the role of liquid immiscibility in controlling magma physical properties

Amphibole: A major carrier of helium isotopes in crustal rocks

The first evidence for a specific role of amphiboles in He isotope balance of crustal rocks was presented in early contributions by Gerling et al. (1971, 1976). Since then it was shown that 4He and 3He concentrations in amphiboles generally exceed those in the host rock samples. Recently amphibole was considered as an important carrier of noble gases and other volatiles components in the course of their subduction into the mantle. This paper presents new data on the balance and mobility of noble gas isotopes and major gas constituents in amphibole separates in order to understand sources and evolution of volatile components of 2666 Ma old alkaline granites from Ponoy massif (Kola Peninsula), which underwent metamorphism 1802 Ma ago.In the amphiboles 3He, 4He and 40Ar* were dominantly produced in situ due to radioactive decay of the parent isotopes and associated nuclear reactions. A small fraction of He (≈ 3% of the total) is liberated by crushing and shows 3He/4He ratio indistinguishable from that found by total extraction. The fraction of trapped 40Ar* amounts to ≈ 40%; both these fractions presumably occupy fluid inclusions and show rather low 4He/40Ar* ≈ 0.1, a factor of ≈ 150 below the production ratio (calculated assuming no loss / gain of the species has happened since the time of metamorphism).3He has been better preserved in amphiboles compared with 4He: the retention parameter (measured amount of He / totally produced amount) for 3He (≈ 0.4) exceeds that for 4He (≈ 0.15).He extraction by fast and slow linear heating of amphiboles resulted in different release patterns. The fast heating (within 12 to 40 °C min− 1) revealed a superposition of two peaks. When heating with slower heating rate (below 8 °C min− 1) was applied, the high-temperature peak disappeared (the “disappearing site”). Extractions of He atoms from grain and powder samples at different heating rates have shown that: (1) the “disappearing site” is revealed by the fast heating analyses of different amphibole samples but not only those from the Ponoy massif; (2) amount of He liberated from the “disappearing site” is variable and generally much less than the total amount of He in the sample; (3) analysis of the powder produced in the crushing experiments never reveals the “disappearing site”; the temperature of He release from the powder is lower than that from the mm grain size sample by ≈ 50 °C. Possible explanations of the nature of the “disappearing site” are discussed. However, independently on nature of this effect, repeated gas extractions by heating at different rates would give additional information about structure and its transformation during heating of amphiboles.The simplest explanation of the observed abundances of noble gas isotopes in the amphibole separates from Ponoy granites suggests local production, redistribution and partial loss of noble gases during evolution of the massif

Effects of fro and HzO on andesite phase relations between 2 and 4 kbar

International audienceExperimentalp hasee quilibriah ave been investigatedo n three medium-K silicic andesite (60-61 wt % SiO2) samples from Mount Pelhe at 2-4 kbar, 850-1040øC, under both vapor-saturatedC O2-freea nd vapor-saturatedC O2-bearingc onditions.M ost experiments were crystallizatione xperimentsu singd ry glassesp reparedf rom the naturalr ocks.B oth normal-a nd rapidq uenche xperimentsw ere performed.T wo rangeso f oxygenf ugacity( fo2) were investigatedN: NO (Ni-NiO buffer) to NNO + 1 and NNO + 2 to NNO + 3. At 2 kbar for moderatelyo xidizing conditionsp, lagioclase( pl) and magnetite( mt) are the liquidus phases, followed by low-Ca pyroxene (opx); these three phases coexist over a large temperature( T)-H20 range( 875-950øC and 5-7 wt % H20 in melt). Amphibole (am) is stable undern ear vapor-saturatedC O2-freec onditionsa t 876øC. At 900øC, ilmenite (ilm) is found only in experimentsle sst hano r equalt o NNO. Upon increasingp ressure( P) underv aporsaturatedC O2-freec onditionsp, l + mt is replacedb y am + mt on the liquidusa bove3 .5 kbar. For highly oxidizingc onditionsm, t is the solel iquidusp hasea t 2 kbar, followed by pl and opx, except in the most H20-rich part of the diagram at 930øC, where opx is replaced by Carich pyroxene( cpx) and am. Compositionso f ferromagnesianp hasess ystematicallyc orrelate with changingfo2E xperimentalg lassesr angef rom andesitict hroughd acitict o rhyolitic, showings ystematicc ompositionavl ariationsw ith pl + opx + mt fractionation( increaseo f SiO2a ndK 20,d ecreasoef A1203C, aO,F eOt, andM gO).F eO*/MgOm oderateilnyc reases with increasingS iO2.F orfo2 conditionst ypical of calk-alkalinem agmatism( approximately NNO + 1), magnetite is either a liquidus or a near-liquidus phase in hydrous silicic andesite magmas,a nd this shoulds timulater eexaminationfo r the mechanismso f generationo f andesitesb y fractionationf rom basalticp arents

Molybdenum Geochemistry in Salt Marsh Pond Sediments

The concentration and isotopic composition of sedimentary molybdenum (Mo) has been used to distinguish different redox environments in modern marine settings and in the geological record. We report Mo concentrations and δ98Mo from porewaters and sediments in three anoxic East Anglian salt marsh pond environments: (1) ‘iron-rich’ sediments containing high concentrations of dissolved ferrous iron (up to 2 mM), (2) ‘sulfide-rich’ sediments containing very high concentrations of aqueous sulfide (up to 10 mM) and, (3) sediments that we consider to be intermediate between ‘iron-rich’ and ‘sulfide-rich’ conditions. In iron-rich sediments, we suggest that iron speciation and mineralogy controls the concentration and isotopic composition of Mo. Despite similar aqueous sulfide profiles, the intermediate and sulfide-rich pond sediment have different porewater Mo concentrations and δ98Mo. In the sulfide-rich pond sediment, we suggest that the concentration and isotopic composition of Mo is controlled by solubility equilibrium with an Fe-Mo-S mineral species (e.g. FeMoS4) due to similarities in sediment and porewater δ98Mo throughout the sediment column. In the intermediate pond sediment, we conclude that active breakdown of iron oxides redistributes porewater Mo, observable as a peak of dissolved Mo (>100ppb), which diffuses within the sedimentary porewaters. The sedimentary δ98Mo is higher in sulfide-rich and intermediate pond sediment (mean = 1.66‰, range = 0.98–1.92‰) than in iron-rich pond sediment (mean = 1.10‰, range = 0.28–1.65‰) with all ponds having sedimentary δ98Mo that is lower than seawater. The maximum sedimentary δ98Mo observed in these anoxic sediments, which is 0.5-0.7‰ lower than seawater, appears to be set by Fe-Mo-S equilibration with ambient thiomolybdate species. We suggest diagenetic overprinting can cause more efficient capture of pond water Mo and causes sediment δ98Mo of originally iron-rich pond sediment to evolve to higher values at progressively higher aqueous sulfide concentrations