We weigh into the debate about whether rising productivity is ever a consequence rather than a cause of exporting. Exporting and investing to raise productivity are complimentary activities. For lower-productivity firms, incurring the fixed costs of such investments is justifiable only if accompanied by the larger sales volumes that come with exporting. Lower foreign tariffs will induce these firms to simultaneously export and invest in productivity. In contrast, lower foreign tariffs will induce higher-productivity firms to export without investing, as in Melitz (2003). We model this econometrically using a heterogeneous response model. Unique 'plant-specific' tariff cuts serve as our instrument for the decision of Canadian plants to start exporting to the United States. We find that those lower-productivity Canadian plants that were induced by the tariff cuts to start exporting (a) increased their labor productivity, (b) engaged in more product innovation, and (c) had high adoption rates of advanced manufacturing technologies. These new exporters also increased their domestic (Canadian) market share at the expense of non-exporters, which suggests that the labor productivity gains reflect underlying gains in TFP. In contrast, we find no effects for higher-productivity plants, just as predicted by our complementarity theory.

Improved Access to Foreign Markets Raises Plant-Level Productivity... for Some Plants

: Interest in the toxicity of tin compounds dates to the early 1800's when investigators demonstrated that inorganic tin compounds produced muscular weakness, loss of pain sensation, and immobility in dogs (Reiter and Ruppert 1984; Idemudia and McMillan 198Gb). In man, organotins can be assimilated by inhalation, absorption through the skin, and from food and drinking water (Zuckerman et al. 1978). The first documented case of organotin poisoning of humans was in 1880 when workers complained of headaches, general weakness, nausea, and diarrhea after exposure to triethyltin acetate vapors (Reiter and Ruppert 1984). Renewed interest in the toxicity of organotin compounds resulted from a medical tragedy in France in 1954. Stalinon, a proprietary compound of diethyltin diiodide plus linoic acid used to treat furuncles and other skin infections, caused 217 poisonings and 111 deaths (Piver 1973; Duncan 1980; Idemudia and McMillan 198Gb). The identified toxic components in Stalinon were triethyltin contaminants; victims received a total dose of 3 grams over a 6- to 8-week period. Symptoms included constant severe headache, rapid weight loss, vomiting, urine retention, vertigo, hypothermia, abdominal pain, and visual and psychic disturbances. Some of the more severely affected patients had convulsions. Death usually occurred in coma or from respiratory or cardiac failure. In survivors, headaches and diminished visual acuity remained for at least 4 years.

/pdf/tin-hazards-to-fish-wildlife-and-invertebrates-a-synoptic-4u83pouue6.pdf

Tin Hazards to Fish, Wildlife, and Invertebrates: A Synoptic Review.

We studied life-history characteristics of Alaskan moose (Alces alces gigas) including the effects of maternal condition of adult females (>33 months old) on sunival and physical condition of young during their first year-of-life. We also examined the relation behveen maternal condition and reproductive parameters of individual adult moose, and tested for effects of those parameters on timing and synchrony of parturition. \t7e radiotracked adult fernales captured in both March 1996 and 1997 throughout the year with intensive monitoring occurring during spring and early summner. That procedure enabled us to capture the offspring of females xire monitored and record other variables related to reproductive success. Females with greater nlmp fat thickness had higher rates of pregnancy, gave birth to more hvins. and produced young with higher birth masses than did females with less rump fat. Time-to-death for indi~idual young increased as birth rnass increased and decreased as birth date and litter size increased; those birth variables, lio\ve\~er. did not act upon time-to-death independently. Our results indicated maternal condition influenced subsequent variables associated wit11 birth, which ultimately affected f i~ t~ t r e sunival of offspring. Further, timing of reproduction varied behveen the 2 years, with births occurring earlier but not more synchronously i11 1996 than in 1997. Time of parturition occurred earlier for individual ferr~ales with the thickest rump fat. That outcolne indicated that timing of parturition was the result of e~nironmental factors acting on fe~nales prior to giving birth rather than effects of attempting to avoici predation. JOURNAL OF WILDLIFE MANAGEMENT 64(2):450-462

Life-history consequences of maternal condition in Alaskan moose

Teeth: List of tables

A review of estimating animal abundance II

Estimating moose population parameters from aerial surveys

Levels of zinc from 3,000 to 12,000 ppm were fed to domestic mallard ducks (Anas platyrhynchos) in their diet. Food intake and body weight both showed closely parallel decreases as the level of zinc in the diet increased. In ducks fed zinc, the pancreas and gonads underwent reductions in relation to body weight, whereas ratios of adrenals and kidneys to body weights increased significantly. No significant change occurred in liver:body weight ratios in ducks fed zinc-supplemented diets. The gonads were so reduced in size that the reproductive function was probably lost. In birds fed zinc-supplemented diets, partial paralysis of the legs, diarrhea, and weight loss were noted within 1!0 days. Severe paralysis, with some ducks unable to waLk, was noted after 20 days. Only slight anemia was present in some ducks after 30 days, but by day 45, extreme anemia (5-13 grams Hb per 100 cc of blood) was evident in most ducks. Normal hemoglobin concentrations averaged 18.6 grams per 100 cc of blood. Significant increases in concerltrations of zinc were found in the liver, kidneys, pancreas, gonads, and breast muscle. High mortality was observed in all groups treated with zinc-supplemented diets; all but 2 of 24 ducks died within 60 days. Paralysis of the legs, high concentrations of zinc in the pancreas and kidneys, and yellowish-red kidneys may be used for diagnosing zinc toxicosis in mallards. Heavy metals such as lead, mercury, copper, and zinc have long been known for their toxicity to animals. Copper and zinc are required as trace elements in the diets of animals, but when they occur in relatively high levels, they become toxic. In this particular set of experiments, toxicity of zinc was studied in domestic mallard ducks to determine the hazard of zinc as an environmental pollutant to waterfowl. This study stems from 70 years of observations, summarized by Chupp and Dalke (1964), of dead and dying ducks, geese, and swans in the Coeur d'Alene Lake area in northern Idaho where zinc is found in high concentrations. The Coeur d'Alene area has been actively mined for at least 70 years and effluents from mines and smelters have been poured into the river systems of the area. These wastes then flow downstream, settling in 1 This investigation was supported by the Society of the Sigma Xi and the senior author's National Defense Education Act Fellowship. 2 Present address: Institute of Arctic Biology, Fairbanks, Alaska. the rivers and lakes, where the aeeumulation of metals beeomes high. Lewis and Deneeke (1923) found 2.86 pereent lead in a sediment sample eolleeted in the Coeur d'Alene valley. Ellis (1940) found a range of 5 to 12 pereent zine in soil enerustations. Chupp and Dalke ( 1964 ) analyzed 12 soil samples (type not stated) and obtained from 150 to 9,600 ppm lead, 240 to 7,700 ppm zine, and 31 to 320 ppm eopper. Three samples of emergent aquatie plants (species not stated) mrere analyzed from which an average of 2,530 ppm lead, 1,930 ppm zine, and 115 ppm eopper were found. As a result, waterfowl that feed in these areas eonsume larger amounts of heavy Inetals than waterfowl feeding in areas of naturally low ( normal ) eoncentrations. Die-offs of dueks, geese, and whistling swans (Olor colaznbianus) have been noted in this area sinee the early 1900's (Chupp and Dalke 1964); however, these die-offs have been variable, oeeurring only in some years. Chupp and Dalke indicated that their tissue analyses for heavy netals and the early studies by the Bureau

Zinc Toxicity in the Mallard Duck

Incisors from 68 known-age moose (Alces alces) were sectioned and the ages of the animals estimated from cementum layers. Mean age determined in this manner overestimated true age by 0.5 yr with errors ranging between minus 1 and plus 3 yr. Cross sections were preferred to longitudinal sections. The major error resulted from difficulties in distinguishing discrete cementum layers. Other sources of error are discussed and the annual sequence of cementum deposition is described. J. WILDL. MANAGE. 42(3):558-563 Age determination of ungulates from cementum layers in teeth has become an accepted technique during the past 2 decades. There are inherent errors with the technique, however, and when relating age to growth, reproduction, or population dynamics, the age estimate should be relatively accurate and the frequency and magnitude of errors known. The errors appear small for some species. Complete agreement of age estimates with known ages was found for 20 black-tailed deer (Odocoileus hemionus columbianus) (Low and Cowan 1963), 46 whitetailed deer (0. virginianus) (Lockard 1972), 16 mule deer (0. hemionus) (Erickson and Seliger 1969), and 18 elk (Cervis canadensis) (Keiss 1969). Nevertheless, Sauer (1973) reported that 16 percent of the age estimates from cementum layers of 69 known-age teeth of white-tailed deer were in error. Similarly, Ranson (1966) did not find total agreement between observable cementum layers and known age in white-tailed deer. Previously published reports on moose age determination using cementum layers (Sergeant and Pimlott 1959, Markgren 1969, Wolfe 1969) suggested a range of accuracy of +1 or 2 yr. None of these works were based on large numbers of known-age teeth. This report describes the accuracy and precision of age estimates from the cementum layers of incisors from 68 known-age moose, compares results from longitudinal and cross sections of cementum, and describes the annual sequence of cementum deposition. We are grateful to E. Kootuk and the members of the Alaska Department of Fish and Game who were responsible for securing and sectioning the known-age teeth and to W. Heimer and D. McKnight for valuable criticism of an early draft of the manuscript. This work was supported by Federal Aid in Wildlife Restoration Project W-17-9. MATERIALS AND METHODS Incisors (1,) were collected from 68 moose tagged as calves in the Matanuska and Tanana Valleys, Alaska and later recovered from hunter kills, live recaptures, train and auto collisions, and natural mortality. If both I, were available, then longitudinal and cross sections of the teeth were prepared. Longitudinal sections were prepared by grinding lateral surfaces of the tooth to produce a thin, medial, dorsal-ventral section of the root. Alternate sides were ground until the section became translucent and cemen558 J. Wildl. Manage. 42(3):1978 This content downloaded from 207.46.13.124 on Wed, 22 Jun 2016 05:47:15 UTC All use subject to http://about.jstor.org/terms ACCURACY OF CEMENTUM MOOSE AGES. Gasaway et al. 559 tum layers could be distinguished readily using a binocular microscope at 10 to 30x magnification. The dorsal cementum has the most distinctive layers and was the portion used for estimating age. A water-bath grinder with a fine abrasive wheel was preferred since it reduced odor, prevented burning of the tooth, and was self-cleaning. Tooth sections were stored in a solution of 70 percent ethanol, 29 percent water, and 1 percent glycerine. Serial cross sections of the 11 root were cut with a lapidary saw fitted with a fine tooth blade (modified from Gilling and Buonocore 1959). Oil was dripped over the tooth to prevent burning. Five 0.3 mm sections were prepared from the proximal half of the root and stored in the above solution. The time required for an experienced individual to cut cross sections is approximately the same as grinding longitudinal sections; however, the initial cost of equipment to cut cross sections is greater. Cementum layers were counted and age was interpreted generally as described by Sergeant and Pimlott (1959). In this study age was reported in whole years for convenience of analysis, although the actual age of each moose exceeded its reported age by the number of months it lived past its last birthday. Annual cementum deposition consists of translucent (light) and opaque (dark) layers when viewed with transmitted light (Fig. 1). Opaque layers are usually deposited during mid to late winter and appear to be mostly complete by April or 2 months prior to the animal's birthday. On a moose's birthday the number of opaque layers theoretically equals its age in years. An age estimate to the nearest month can be made when the month the animal died is known. Most births occur during late May in Alaska; therefore, if P~B~pna~Jla~ 3 + ~P"F~.~ r~u~ :?~i~L,

https://www.jstor.org/stable/pdfplus/3800818.pdf

Accuracy of Moose Age Determinations from Incisor Cementum Layers

Precisions sur les biais methodologiques lors du denombrement par voie aerienne (methode des transects) d'Alces alces dans les basses terres des Tanana Flats, Alaska. La diminution de ces biais est possible mais augmenterait le cout de l'operation

William C. Gasaway

Papers

Estimating moose population parameters from aerial surveys

Zinc Toxicity in the Mallard Duck

Accuracy of Moose Age Determinations from Incisor Cementum Layers

Biases in aerial transect surveys for moose during may and june

Immobilizing Moose with a Mixture of Etrophine and Xylazine Hydrochloride