26 research outputs found

    Effects of Mineral Nutrition on Components of Reproduction in Clarkia ungucilata

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    An experiment was conducted to determine the effects of nutritional level and flower location on factors related to flower, pollen, and ovule production, and to determine what developmental patterns would be modified to mediate any observed changes. Plants subjected to high nutrient levels developed larger leaves, more branches, more flowers on both the main stem and the branches, and opened their first flowers 6 days sooner than plants at lower levels of nutrients. Total flower number increased from 72.2 to 626.8 per plant, with most of the increase produced on the primary branches. The number of pollen grains in the entire androecium averaged 14,685, but significantly increased with higher nutrient levels and decreased with the stage of plant maturity (nodal position on the plant). The number of ovules also increased with nutrient level and decreased with maturity stage. Average ovule number decreased from about 129 in flowers at nodes produced early in the growth cycle to about 100 in flowers produced at later nodes. Despite highly significant plasticity in numbers of both pollen and ovules, the Pollen/Ovule Ratio (average 132.7) did not vary significantly with either nutrient level or plant maturity stage. Path analysis, which decomposes correlation coefficients into direct and indirect effects of factors influencing development, indicated that nutrient level had a very strong direct effect on the number of primary branches and on the number of primary-branch flowers, as well as very strong indirect effects on the latter. The primary-branch flowers directly determined over 67% of the total flower number, and indirectly determined about 24% jointly with secondary-branch flowers, and over 3% jointly with main-stem flowers. The direct effects of secondary-branch flowers and mainstem flowers were 3.8% and 0.3%, respectively. The relationship among components of yield is slightly additive. Direct determination of yield was 74.6% by the number of flowers per plant, 0.6% by the number of ovules per flower, 3.8% by the number of seeds per ovule, and 1.1 % by the weight per seed. The proportion of yield jointly determined by flower number and the developed seeds per ovule was 15.3%. It was concluded that allocation of resources increases to both male and female functions under conditions of high nutrient levels, and pollen/ovule ratios are consistent within a plant despite significant plasticity in numbers of pollen grains and ovules

    Forced mobilization accelerates pathogenesis: characterization of a preclinical surgical model of osteoarthritis

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    Preclinical osteoarthritis (OA) models are often employed in studies investigating disease-modifying OA drugs (DMOADs). In this study we present a comprehensive, longitudinal evaluation of OA pathogenesis in a rat model of OA, including histologic and biochemical analyses of articular cartilage degradation and assessment of subchondral bone sclerosis. Male Sprague-Dawley rats underwent joint destabilization surgery by anterior cruciate ligament transection and partial medial meniscectomy. The contralateral joint was evaluated as a secondary treatment, and sham surgery was performed in a separate group of animals (controls). Furthermore, the effects of walking on a rotating cylinder (to force mobilization of the joint) on OA pathogenesis were assessed. Destabilization-induced OA was investigated at several time points up to 20 weeks after surgery using Osteoarthritis Research Society International histopathology scores, in vivo micro-computed tomography (CT) volumetric bone mineral density analysis, and biochemical analysis of type II collagen breakdown using the CTX II biomarker. Expression of hypertrophic chondrocyte markers was also assessed in articular cartilage. Cartilage degradation, subchondral changes, and subchondral bone loss were observed as early as 2 weeks after surgery, with considerable correlation to that seen in human OA. We found excellent correlation between histologic changes and micro-CT analysis of underlying bone, which reflected properties of human OA, and identified additional molecular changes that enhance our understanding of OA pathogenesis. Interestingly, forced mobilization exercise accelerated OA progression. Minor OA activity was also observed in the contralateral joint, including proteoglycan loss. Finally, we observed increased chondrocyte hypertrophy during pathogenesis. We conclude that forced mobilization accelerates OA damage in the destabilized joint. This surgical model of OA with forced mobilization is suitable for longitudinal preclinical studies, and it is well adapted for investigation of both early and late stages of OA. The time course of OA progression can be modulated through the use of forced mobilization

    SmartOTPs: An Air-Gapped 2-Factor Authentication for Smart-Contract Wallets

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    With the recent rise of cryptocurrencies' popularity, the security and management of crypto-tokens have become critical. We have witnessed many attacks on users and providers, which have resulted in significant financial losses. To remedy these issues, several wallet solutions have been proposed. However, these solutions often lack either essential security features, usability, or do not allow users to customize their spending rules. In this paper, we propose SmartOTPs, a smart-contract wallet framework that gives a flexible, usable, and secure way of managing crypto-tokens in a self-sovereign fashion. The proposed framework consists of four components (i.e., an authenticator, a client, a hardware wallet, and a smart contract), and it provides 2-factor authentication (2FA) performed in two stages of interaction with the blockchain. To the best of our knowledge, our framework is the first one that utilizes one-time passwords (OTPs) in the setting of the public blockchain. In SmartOTPs, the OTPs are aggregated by a Merkle tree and hash chains whereby for each authentication only a short OTP (e.g., 16B-long) is transferred from the authenticator to the client. Such a novel setting enables us to make a fully air-gapped authenticator by utilizing small QR codes or a few mnemonic words, while additionally offering resilience against quantum cryptanalysis. We have made a proof-of-concept based on the Ethereum platform. Our cost analysis shows that the average cost of a transfer operation is comparable to existing 2FA solutions using smart contracts with multi-signatures

    TWO NEW SPECIES RELATED TO CLARKIA UNGUICULATA

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    Volume: 17Start Page: 219End Page: 22

    JEFFREY PINE AND VEGETATION OF THE SOUTHERN MODOC NATIONAL FOREST

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    Volume: 25Start Page: 9End Page: 3

    Distribution of Polygala acanthoclada

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    Volume: 30Start Page: 193End Page: 19

    CLARKIA EXILIS, A NEW CALIFORNIAN SPECIES

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    Volume: 12Start Page: 211End Page: 21

    POLLEN SIRING SUCCESS IN THE CALIFORNIA WILDFLOWER CLARKIA UNGUICULATA (ONAGRACEAE)

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    Volume: 58Start Page: 78End Page: 8
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