Maple Leaf Research Articles

Spring leaf phenology and the diurnal temperature range in a temperate maple forest

Spring leaf phenology in temperate climates is intricately related to numerous aspects of the lower atmosphere [e.g., surface energy balance, carbon flux, humidity, the diurnal temperature range (DTR)]. To further develop and improve the accuracy of ecosystem and climate models, additional investigations of the specific nature of the relationships between spring leaf phenology and various ecosystem and climate processes are required in different environments. This study used visual observations of maple leaf phenology, below-canopy light intensities, and micrometeorological data collected during the spring seasons of 2008, 2009, and 2010 to examine the potential influence of leaf phenology on a seasonal transition in the trend of the DTR. The timing of a reversal in the DTR trend occurred near the time when the leaves were unfolding and expanding. The results suggest that the spring decline in the DTR can be attributed primarily to the effect of canopy closure on daily maximum temperature. These findings improve our understanding of the relationship between leaf phenology and the diurnal temperature range in temperate maple forests during the spring. They also demonstrate the necessity of incorporating accurate phenological data into ecosystem and climate models and warrant a careful examination of the extent to which canopy phenology is currently incorporated into existing models.

Retention on third agents in HAART regimens at the Maple Leaf Clinic in Toronto, Ontario, Canada

This study evaluated the 12‐month retention rate of third agents in HAART (highly active anti‐retroviral therapy) regimens in routine clinical practice in a Canadian HIV clinic. This is a descriptive retrospective database analysis of HIV‐positive patients naïve to antiretroviral therapy (ART). The study included male and female HIV patients≥18 years of age at HAART initiation date, seen in routine consultation at the Maple Leaf Medical Clinic (MLMC), Toronto, Ontario, Canada. Data were extracted from the MLMC database for the period of September 1st, 2003 to August 31st, 2010 for patients who commenced a protease inhibitor (PI), a non‐nucleoside reverse‐transcriptase inhibitor (NNRTI), or an integrase inhibitor (II) ‐based regimen in combination with two nucleoside reverse transcriptase inhibitors (NRTI). Demographic and baseline disease characteristics were extracted and include age, gender, disease duration, baseline HIV‐1 RNA count, CD4 cell count, and hepatitis B and C co‐infection status at baseline. A total of 722 patients were included in the analysis. The primary outcome of the study was the proportion of HIV patients remaining on their initial third agent (PI, NNRTI, or II) at one year post‐treatment initiation. For therapies used by more than 10% of patients (efavirenz [EFV]=315, atazanavir [ATV]=104, lopinavir [LPV]=162, as other agents were used but in limited numbers), the percentage of patients still on the initial third agents at one year was 77%, 64% and 62%, respectively. In addition, viral load (VL) was less than 50 copies/mL in 95% of EFV, 79% of ATV and 76% of LPV patients at one year. The rate of discontinuation at 12 months from EFV, ATV, and LPV due to efficacy (i.e. lack of virologic suppression) or safety (i.e. adverse events) were 15.56%, 19.23%, and 19.75% respectively. In a clinical practice setting, the majority of patients treated with HAART regimens were maintained on therapy at one year and were able to suppress their viral load consistently. Of those reported here, EFV resulted in the best retention rate and viral suppression overall.

Looking Back 50 Years in Hospital Administration

Healthcare policy and hospital administration are dynamic and growing fields, oriented toward shaping the future. In an effort to understand where these fields have come from, as well as some of the re-occuring challenges faced, we conducted a retrospective analysis. Our research identified progress and major accomplishments, as well as issues that continue to challenge the field in five key areas: (1) the evolution of nursing, (2) funding and legislation, (3) hospital design, construction and technology, (4) patient care and infection control and (5) leadership. To explore these areas, a thematic content review was conducted on the 12 inaugural issues of Hospital Administration in Canada, a hospital administration periodical from 1962. All written content was reviewed, coded and categorized into major themes that represented the major hospital administration topics of 50 years ago. In this article, five prominent themes are explored and further illustrated using key stories and milestones from 1962.

School Improvement

Maple Leaf School is a large English elementary school in Ontario, Canada. Wanda Miller, the principal, has been at the school for 2 years. Upon arrival, she engaged the teachers in a collaborative exercise to determine their school goal (as required by the province). Character education was selected. The district insisted that the school adopt an academic goal instead. Wanda determined that character education would be the school’s primary goal and writing its secondary one. Since then, students’ behavior and the school’s climate have improved markedly, but test scores have declined. This case focuses on the tension between a locally identified, collaboratively determined school focus and conflicting district and provincial demands.

Indexical Color Predicates: Truth Conditional Semantics vs. Truth Conditional Pragmatics

Truth conditional semantics is the project of ‘determining a way of assigning truth conditions to sentences based on A) the extension of their constituents and B) their syntactic mode of combination’ (Rothschild and Segal, 2009). This research program has been subject to objections that take the form of underdetermination arguments, an influential instance of which is presented by Travis: … consider the words ‘The leaf is green,’ speaking of a given leaf, and its condition at a given time, used so as to mean what they do mean in English. How many distinct things might be said in words with all that true of them? Many.… Suppose a Japanese maple leaf, turned brown, was painted green for a decoration. In sorting leaves by colour, one might truly call this one green. In describing leaves to help identify their species, it might, for all the paint, be false to call it that.

More maple leaf, less CO2: Canada and a global geo-engineering regime

While US-led unipolarity may still be the guiding frame for post-Cold War international economic, political, and military relations, we argue that its applicability to global science and environmental issues is waning. We begin by discussing the global problem of anthropogenic climate change, and the technologies involved in geo-engineering as one possible response. We then recognize both the abundance of oil in Alberta and the near-term melting of the Arctic as critical inputs into Canadian climate change policy. Finally, we examine Canada's abilities and resources as a middle power to act as a foreign policy leader in the formation of a global geo-engineering regime.

An Old Testament Offering: The Origin of Frost's “Maple”

Frost's poem, “Maple,” raises three distinct issues: 1) What is the significance of the name “Maple” and of the circumstances contributing to the naming of Maple? 2) What is the significance of the phrase “wave offering” in the biblical passages where the maple leaf was found? and 3) What does the poem mean? My thesis centers on a biblical and etymological analysis of the Hebrew word for “offering” that is central to Frost's poem. The paper begins with an investigation into the Old Testament origins of this phrase and then analyzes the significance of Maple's naming and the poem's relevance to Frost's themes and previous poems.

マルチワイヤーチェンバーによる楓葉の2次元影像

マルチワイヤーチェンバーによる楓葉の2次元影像

マルチワイヤーチェンバーによる楓葉の2次元影像

素粒子，原子核実験の分野で広く使用されているマルチワイヤーチェンバー(multi-wire chamber)を進展させ，アノードワイヤーのピッチpaを狭く(1mm)にし，位置精度のよいチェンバーを試作した。アノードワイヤー面とグリッドワイヤー面は平行で，簡易に2次元的情報を得るようワイヤーの方向は互いに直角にした。設計にあたっては経験やシミュレーションに頼らず，電磁気学の基本に立ち，チェンバーの諸特性を解析的に求めた。信号の読み出しには独特の荷電分割法を開発し，信号は計4個のプリアンプで処理した。チェンバーの性能確認には，241Amから放出されるα線を使って「楓の葉」をサンプルにして影像を描かせて行った。アノードワイヤーのピッチが狭くてもチェンバーは稼働する。主要な特性を解析的に設計したチェンバーで平面スクリーン上に2次元的に，鮮明な「楓の葉」を映し出すことができた。

The Maple Leaf Foods recall: best practice interaction during a food-related crisis

Crisis situations for organisations prompt public responses to manage the effects of the crisis and maintain public confidence in the organisation or the safety of its products. This study of the Maple Leaf Foods listeriosis crisis of 2008 and the recall of its products examined the company’s responses made after the recall to determine if they reflected the presence of best practices. The findings suggested that the strategic utilisation of particular audience-centred best practices enabled the company chief executive officer to focus on re-establishing public trust in the safety of its products. Prioritising organisational objectives as early in the crisis as possible, demonstrating flexibility when determining which best practice to use, and communicating quickly, honestly, and empathetically with the public are offered as practical suggestions for communication scholars and organisations experiencing crises.

Impacts of Microbial Activity on the Optical and Copper-Binding Properties of Leaf-Litter Leachate

Dissolved organic matter (DOM) is a universal part of all aquatic systems that largely originates with the decay of plant and animal tissue. Its polyelectrolytic and heterogeneous characters make it an effective metal-complexing agent with highly diverse characteristics. Microbes utilize DOM as a source of nutrients and energy and their enzymatic activity may change its composition, thereby altering the bioavailability and toxicity of metals. This study investigated the impacts of microbial inoculation upon the optical and copper-binding properties of freshly produced leaf-litter leachate over 168 h. Copper speciation was measured using voltammetry, and using fluorescence quenching analysis of independent fluorophores determined using parallel factor analysis (PARAFAC). Two protein/polyphenol-like and two fulvic/humic-like components were detected. Thirty-five percent of total protein/polyphenol-like fluorescence was removed after 168-h of exposure to riverine microbes. The microbial humic-like and tryptophan-like PARAFAC components retained significantly different log K values after 168 h of incubation (p < 0.05), while their complexing capacities were similar. Using voltammetry, a sixfold increase in copper-complexing capacity (CC, from 130 to 770 μmol Cu g C−1) was observed over the exposure period, while the conditional binding constant (log K) decreased from 7.2 to 5.8. Overall binding parameters determined using voltammetry and fluorescence quenching were in agreement. However, the electrochemically based binding strength was significantly greater than that exhibited by any of the PARAFAC components, which may be due to the impact of non-fluorescent DOM, or differences in the concentration ranges of metals analyzed (i.e., different analytical windows). It was concluded that the microbial metabolization of maple leaf leachate has a significant impact upon DOM composition and its copper-binding characteristics.

Hierarchical Porous Ceria Synthesized by Maple Leaf Templates and Its Catalytic Performance

Hierarchical porous ceria with nanocrystalline was successfully synthesized using maple leaf as a biotemplate.Unique biomorphic microstructures were characterized by Field Emission Scanning Electron Microscope(FESEM),transmission electron microscope(TEM) and nitrogen absorption-desorption technique.The obtained ceria material shows the repetitious biomimetic structure consisting of the stoma porous about several μm and nanopores with 2 4 nm apertures.The small crystal grain(6 8 nm) and the high specific surface area(64.4 m2/g) of porous CeO2 are detected by wide-angle X-ray diffraction(XRD),high resolution TEM(HRTEM) and the BET method.The catalytic property is evaluated by the oxygen storage/release capacity(OSC).The test confirms that hierarchical porous material possesses more surface active oxygen than nonporous ceria does.While the concentration of acid fuchsine is 40 mg/L,the porous sample has a higher decoloring rate in a shorter time than others.The decoloring rate can reach 100% after decolored for 300 min.The investigation infers that the hierarchical porous ceria exhibits better catalytic activity and higher adsorptive capacity in dye wastewater purification due to smaller crystallite size,higher surface area and enhanced OSC.

Effects of Maple (Acer) Plant Part Extracts on Proliferation, Apoptosis and Cell Cycle Arrest of Human Tumorigenic and Non‐tumorigenic Colon Cells

Phenolic-enriched extracts of maple sap and syrup, obtained from the sugar and red maple species (Acer saccharum Marsh, A. rubrum L., respectively), are reported to show anticancer effects. Despite traditional medicinal uses of various other parts of these plants by Native Americans, they have not been investigated for anticancer activity. Here leaves, stems/twigs, barks and sapwoods of both maple species were evaluated for antiproliferative effects against human colon tumorigenic (HCT-116, HT-29, Caco-2) and non-tumorigenic (CCD-18Co) cells. Extracts were standardized to total phenolic and ginnalin-A (isolated in our laboratory) levels. Overall, the extracts inhibited the growth of the colon cancer more than normal cells (over two-fold), their activities increased with their ginnalin-A levels, with red > sugar maple extracts. The red maple leaf extract, which contained the highest ginnalin-A content, was the most active extract (IC₅₀ = 35 and 16 µg/mL for extract and ginnalin-A, respectively). The extracts were not cytotoxic nor did they induce apoptosis of the colon cancer cells. However, cell cycle analyses revealed that the antiproliferative effects of the extracts were mediated through cell cycle arrest in the S-phase. The results from the current study suggest that these maple plant part extracts may have potential anticolon cancer effects.

Reproduction of aquatic hyphomycetes at low concentrations of Ca2+, Zn2+, Cu2+, and Cd2+

Maple leaf disks were conditioned in a stream for three weeks and then aerated for 2 d in distilled water to induce fungal sporulation. The release of aquatic hyphomycete spores increased when the water was supplemented with low concentrations of Ca(2+) (5 µg/L), Zn(2+) (2.5 µg/L), Cu(2+) (0.5 µg/L), or Cd(2+) (0.125 µg/L). Higher supplement concentrations inhibited sporulation. Over the concentration range used, the sporulation response was generally best described by a quadratic regression, suggesting a biphasic or hormetic response. A similar pattern was found with the number of fungal species as the dependent variable. Anguillospora filiformis and Anguillospora longissima were generally least inhibited by metal supplements, and Ca(2+) was the least and Cd(2+) the most toxic metal. Combinations of metals had a more severe effect on fungal sporulation than predicted from addition of the effects of the metals in isolation. The biological significance of the hormetic response is unclear; however, acknowledging it is clearly relevant for establishing guidelines or recommendations in toxicology.

Red maple dominance enhances fungal and shredder growth and litter processing in temporary ponds

We used in situ and laboratory mesocosm experiments to test the effects of red maple (Acer rubrum), white oak (Quercus alba), and northern red oak (Q. rubra) leaf litter on microbial biomass and detritivore (Limnephilus indivisus) growth, survival, and organic matter processing in temporary forest ponds. Fungal biomass was highest in red maple leaf litter but was reduced in both maple and oak litter by detritivore presence, indicating a foraging preference based on fungal biomass. Organic matter processing and fine particulate organic matter (FPOM) generation rates were highest in red maple treatments containing detritivores, and red maple diets allowed for rapid larval growth and development to adulthood, while oak diets (Q. alba or Q. rubra) resulted in slower development and increased mortality of larvae. Red maple dominance around pond margins may have positive effects on detritivore growth and generation of FPOM in temporary ponds. Because many of the organisms that feed on FPOM also serve as prey for larval amphibians, the effects of increased FPOM production resulting from red maple dominance may travel through the food web to affect higher trophic levels.

Leaf Diet Affects Growth of a Shredder,Limnephilus indivisus, from a Seasonal New England Pond

Deciduous leaf litter is often a primary source of energy at the base of the food web in seasonal woodland ponds (e.g., vernal or autumnal pools), which are common in the northeastern United States. It is therefore important to understand how leaf diet af- fects growth of detritivores, such as the caddisfl y Limnephilus indivisus Walker, that feed almost exclusively on submerged plant matter in seasonal pond systems. Growth may relate to how rapidly a caddisfl y is able to complete its larval development and pupate, and hence its ability to survive in small ponds with short hydroperiods. Growth is also related to the maximum size the larva achieves. In many organisms, attaining a larger size conveys several distinct advantages: larger individuals typically have higher survival rates and increased fecundity, and hence greater fi tness compared to smaller conspecifi cs or competing sympatric species. To assess how leaf diet infl uences the growth of larvae of L. indivisus, we conducted a controlled experiment to test how different leaf diets in- fl uenced larval growth. The leaf diet experiment was set up as follows: Treatment 1: Acer rubrum (Red Maple), Treatment 2: Quercus spp. (oak), and Treatment 3: Red Maple and oak. L. indivisus that were fed oak leaves or a mix of oak and Red Maple leaves grew signifi cantly larger than larvae fed Red Maple leaves only. In Treatment 3, the caddisfl y was observed more frequently on the oak leaf compared to the Red Maple leaf. Although L. indivisus selected oak leaves more often during the experiment, oak leaves were less abundant than maple leaves at our study site. We hypothesize that the oak leaves provide more nutrients to L. indivisus due to a combination of physical, biological, and chemical properties which results in more larval growth.

Changes in photosynthetic performance and antioxidative strategies during maturation of Norway maple (Acer platanoides L.) leaves

Different structural and functional changes take place during leaf development. Since some of them are highly connected to oxidative metabolism, regulation of reactive oxygen species (ROS) abundance is required. Most of the reactive oxygen species ROS in plant cells are produced in chloroplasts as a result of highly energetic reactions of photosynthesis. The aim of our study was to examine the changes in concentration of oxidative stress parameters (TBARS - thiobarbituric acid-reacting substances and protein carbonyls) as well as antioxidative strategies during development of maple (Acer platanoides L.) leaves in the light of their enhanced photosynthetic performance. We reveal that biogenesis of the photosynthetic apparatus during maple leaf maturation corresponded with oxidative damage of lipids, but not proteins. In addition, antioxidative responses in young leaves differed from that in older leaves. Young leaves had high values of non-photochemical quenching (NPQ) and catalase (CAT, EC 1.11.1.6) activity which declined during the maturation process. Developing leaves were characterized by an increase in TBARS level, the content of non-enzymatic antioxidants as well as ascorbate peroxidase activity (APX, EC 1.11.1.11), while the content of protein carbonyls decreased with leaf maturation. Fully developed leaves had the highest lipid peroxidation level accompanied by a maximum in ascorbic acid content and superoxide dismutase activity (SOD, EC1.15.1.1). These observations imply completely different antioxidative strategies during leaf maturation enabling them to perform their basic function.

Enhancing effects of adjuvanted 2009 pandemic H1N1 influenza A vaccine on memory B-cell responses in HIV-infected individuals.

To assess the humoral immune response to low-dose AS03-adjuvanted and standard-dose nonadjuvanted 2009 pandemic H1N1 influenza A vaccine in HIV-infected aviremic individuals receiving antiretroviral therapy and in uninfected individuals. A three-arm study. Two clinics: one at the National Institutes of Health in Bethesda, Maryland, USA; and the other at the Maple Leaf Medical Clinic in Toronto, Ontario, Canada. HIV-infected and HIV-uninfected adults. Single intramuscular 15 μg dose of the monovalent inactivated 2009 pandemic H1N1 influenza A vaccine without adjuvant or 3.75 μg dose of the same strain with adjuvant AS03. Immunogenicity, as measured by hemagglutination inhibition (HAI) antibody titers and vaccine-specific memory B-cell responses. A total of 74 participants were enrolled. Twenty-one HIV-infected individuals received the low-dose adjuvanted 2009 pandemic H1N1 influenza A vaccine. Twenty-nine HIV-infected and 24 HIV-uninfected individuals received the standard-dose nonadjuvanted vaccine. There were no significant differences in antibody responses at 9 weeks postvaccination among the three groups studied. However, the IgG memory B-cell response against the vaccine was significantly higher in the HIV-infected group that received the low-dose adjuvanted vaccine when compared to the HIV-infected and uninfected groups that received the standard-dose nonadjuvanted vaccine. Conclusions remained unchanged after regression adjustment for age, gender, CD4 T-cell count, and baseline HAI titer. These data suggest that adjuvants could be used to expand coverage through dose sparing and improve humoral immune responses in immunocompromised individuals.

Sakura in the Land of the Maple Leaf: Japanese Cultural Traditions in Canada (review)

Sakura in the Land of the Maple Leaf: Japanese Cultural Traditions in Canada (review)

Methodological artefacts in the XANES analysis of hexa-coordinated pentavalent arsenic

Using XANES, we studied the recently identified hexa-coordinated pentavalent arsenic, specifically, octahedral As(V)-glycerol compound As(V)(OCH2CH(O)CH2OH)3. It is stable at all pHs tested (1–12), but is transformed to the conventional tetrahedral AsO43− compound in the presence of water. Dehydration of environmental samples (i.e., Manitoba maple leaf and hare muscle) spiked with a AsO43− standard resulted in XANES features of the As(V)-glycerol compound. Therefore the compound we hypothesize to be the As(V)-glycerol in environmental samples is likely only visible using XAS analysis, and does not appear to survive wet environments such as those in biological systems, where toxicity may be experienced, or in conventional speciation methods, which generally use aqueous separation techniques.