New Releases by Margaret Davidson

Reprint of the original, first published in 1841.

Learn all about Helen Keller''s inspiring life. A biography stressing the childhood of the woman who overcame the handicaps of being blind and deaf.

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Much attention is devoted to understanding whole plant physiology and the architectural manipulation of fruit tree canopies to optimize yield, minimize excessive vegetative growth and to understand developmental responses to the environment. One method to visualize and understand plant physiological responses is to synthesize field data sets into mechanistically based computer simulation models. The L-PEACH model is a functional-structural interactive plant model that simulates 3D peach tree architecture, carbohydrate flow and dry matter distribution. The construction of a virtual tree is based on phytomers, repetitive subunits defined as node+leaf+axillary meristem+internodal segments. The time elapsing between the additions of phytomers can be represented by the appearance of leaves at every node known as the leaf appearance rate (LAR). The inverse of LAR is the phyllochron, the time or thermal time elapsing between the appearances of successive leaves along a stem. Plant genotype interactions with environment are responsible for the timing of the phyllochron. Temperature is thought to be most responsible for regulating the phyllochron. Therefore the first objective of this study was to observe the effects of temperature on the phyllochron and to determine the cardinal minimum, optimum and maximum values of a growing-degree-hour model for measuring the phyllochron of Prunus persica of proleptic shoots of field-grown trees. The cardinal temperatures were as follows: minimum (4°C), the optimal range (18-32°C) and the maximum temperature (40°C). Using the GDH or time scale, the phyllochron of proleptic shoots fluctuated and generally increased over the season. This slowing of the phyllochron over the season is likely due to an endogenous rank effect.Previous studies in peach reported shorter shoots under water deficit treatments. In annual crops, studies show that irrigation affects the phyllochron, but we were uncertain of how water deficit affects incremental growth (i.e., the phyllochron) in peach. For this reason, we observed the phyllochron for both proleptic and epicormic shoots in well-watered and water deficit treatments. The phyllochron of epicormic shoots in 2010 had significant differences between water treatments while phyllochrons for epicormic shoots in 2011 remained unaffected. Likewise the phyllochron for proleptic shoots also remained unaffected.The L-PEACH is a carbon balance model; therefore, we were interested in seeing how carbon availability affected the phyllochron. Carbohydrate availability for vegetative growth is influenced by crop load, as fruits compete as strong sinks for photosynthate. Crop load is known to have significant effects on shoot growth rates, but we did not know how it would affect the tree on a phytomer scale. To answer this question, 100% of the fruit were removed from trees in an un-cropped treatment, while other trees were left un-thinned. The phyllochron of epicormic and proleptic shoots was significantly greater on trees with heavy crop loads. These findings indicate that the phyllochron of field-grown peach trees is apparently sensitive to carbohydrate availability. This led us to our final hypothesis, that excess carbon availability would therefore decrease the phyllochron.To test this hypothesis, a 38-day growth chamber study was conducted to determine if elevated CO2 decreased the phyllochron. Young Prunus persica plants were grown in concentrations of either ambient (~400 ppmv) or elevated (~800 ppmv) CO2. Doubling ambient CO2 concentration had no effect on the phyllochron even though leaf CO2 assimilation rates, leaf starch and total non-structural carbohydrate concentrations were greater in trees grown in elevated CO2. Additionally there were no significant treatment differences in incremental shoot growth or number of lateral syleptic shoots.These studies allowed us to address the fundamental biological question of what regulates the phyllochron in a perennial fruit tree. The findings in the aforementioned studies will be incorporated into the L-PEACH model to allow for more accurate simulations and predictions of physiological growth in response to environmental and cultural factors.

First Published in 1990. Written by an editor and now Journalism Professor, who when directing stringers in New York state, who was struck by the tremendous desire of those correspondents to learn and grow in their job, despite the paltry pay they received for their efforts. This guide has been prepared to help meet the stringer’s need for constructive criticism. It assumes that all places are interesting and full of newsworthy activities for a professional writer with a good nose for news.

Drawing is experiencing an unparalleled surge in the art world. Passé notions that once defined drawing as being a preparatory stage for painting or sculpture have long since been cast aside. Drawing is now fully recognized as its own art form—in the biennials, art fairs, museum exhibitions, and beyond. Drawing has come of age. Contemporary artists are increasingly discovering that drawing is something unique and different from painting. It is an intense, sensitive, compelling, personal, and utterly direct art form, one with its own concepts, characteristics, and techniques. In addition, contemporary drawing is not governed by any particular imagery, but rather encompasses a variety of approaches, including realist, abstract, modernist, and post-modernist. Contemporary Drawing delves into the essential and far-reaching concepts of this medium, exploring surface, mark, space, composition, scale, materials, and intentionality in turn. Key techniques, such as using nature to induce marks and working with a checklist to determine a drawing’s problems, are introduced throughout. Plus, an in-depth chapter examines a number of artists, such as William Kentridge and Gego, who are breaking traditional boundaries that separate one artistic discipline from another. Lushly illustrated by a wide range of highly accomplished contemporary artists, Contemporary Drawing offers a broad perspective on this expansive and energized field of art.

Nous sommes en 1880, aux Etats-Unis. A la suite d''une scarlatine, la petite Helen Keller devient aveugle, sourde et muette. Plus elle grandit, plus elle s''enferme dans la solitude et la colère. Désespérés, ses parents font appel à Annie Sullivan. La jeune femme, elle-même presque aveugle, accomplit le miracle de transformer Helen, violente petite rebelle, en une brillante étudiante connue du monde entier. L''histoire vraie d''Helen Keller, le récit d''un incroyable défi ; une leçon de courage et d''espoir.

Louis Braille est devenu aveugle à l''âge de trois ans à la suite d''un accident. Cela ne l''empêche pas de vivre presque comme les autres enfants. Mais à l''école, les difficultés commencent, car il veut apprendre à lire... Le jeune garçon se fait alors une promesse incroyable : il trouvera le moyen de déchiffrer ce que ses yeux ne peuvent voir.

A la suite d''un accident, Louis Braille est devenu aveugle à l''âge de trois ans. Mais cela ne l''empêche pas de vivre presque comme tous les autres enfants. C''est à l''école que les difficultés vont commencer car il veut apprendre à lire. Loin de se décourager, Louis se fait alors une promesse incroyable : il trouvera le moyen de déchiffrer ce que ses yeux ne peuvent voir. Après avoir lu cette histoire authentique, découvre les pages du supplément illustré pour en savoir plus.

A retelling of the story of Balto, the sled dog who led the final relay team carrying life-saving serum to Nome during the 1925 diptheria epidemic.

Discusses behavior common to mammal babies involving their birth, feeding, homes, safety, growth, and independence from parents.

Delves into the life of the inventor Edison, recounting the joys, tragedies, and successes of his life, and explains the scientific principles behind his revolutionary work.

Readers meet many fascinating dolphins while learning how they survive, how scientists study them and more.