1,385 research outputs found

    From Mexico to Michigan and back: An international collaboration investigating primate behavior, ecology, and evolution from multiple perspectives

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    Evolutionary research benefits form the integration of laboratory and field components to determine factors and processes that affect the evolutionary trajectories of species. Our shared interest in understanding hybridization with genetic admixture as a process that may impact social, behavioral, and ecological features of primates, brought us together in a collaborative project aimed at addressing how vocal variation in two species of howler monkeys in Mexico affects and is affected by hybridization. To achieve this goal, we joined our academic expertise in studying primate genetics, ecology, and behavior under different natural and experimental conditions. We took advantage of decades of experience studying and handing wild howler monkeys for translocation projects to safely sample and study wild populations for this project. Here, we describe the history of our collaboration highlighting how our different perspectives, academic realities, and individual strengths built the foundation for our successful collaboration. We also share our perspectives on how this collaboration opened up new academic venues, broadened our individual perspectives on the integration of different research approaches to address a complex topic, and allowed us to recognize the strength of international collaboration.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/149745/1/ajp22992_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149745/2/ajp22992.pd

    An alternative index of abundance for Atlantic skipjack (Katsuwonus pelamis) based on catch ratio and abundance of a reference species.

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    Indices of abundance, frequently based on catch rates per unit effort (CPUE), are one of the main inputs to tropical tuna stock assessments. While standardized longline CPUE series are routinely obtained and used in the stock assessments of yellowfin and bigeye tunas, the standardization of the effort in fisheries targeting skipjack tuna is more problematic, due to several factors that are known to affect the efficiency of the fleets but are difficult to quantify. In this scenario, alternative approaches need to be tested. In this document, we propose an alternative approach based on the ratio in the catch of skipjack vs yellowfin tuna, using the abundance of the reference species as an offset in the standardization.En prens

    Ensiling Alfalfa (Medicago sativa L.) and Orchard Grass (Dactylis glomerata L.) Forage Harvested at 08:00 or 14:00, without Wilting or 1 or 2 h Wilting and with or without Use of Bacterial Inoculant

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    Alfalfa forage is difficult to ensile due to low water-soluble carbohydrate content and high buffering capacity. The objective was to assess at Chapingo, Mexico, during the rainy season effects of combinations of harvest hours (08:00, 14:00), wilting time (0, 1, 2 h) and bacterial inoculants on the quality of silage made of alfalfa and orchard grass forage, made in 200-L containers. The experiment was conducted in three phases with two replicates per phase. Variables measured in freshly cut forage and silages were dry matter content (DM), buffer capacity, pH, and alcohol soluble carbohydrates (ASC). Silos remained sealed during 60 d, and additional variables measured in silage were aerobic stability, NH3 -N and in vitro disappearance of DM. In forage harvested at 14:00 h, DM and ASC contents were higher; pH and buffering capacity were not affected by harvest hour; in silages made of that forage, NH3-N levels were lower, while ASC contents and in vitro disappearance of MS were unaffected by harvest hour. Treatments with inoculants were less aerobic stable for 5 days when made of forage harvested at 08:00 h but more stable when made of forage harvested at 14:00 h. Harvesting at 14:00 h was advantageous as silage presented higher DM and ASC contents

    Exploring the Design of Highly Energy Efficient Forestry Cranes using Gravity Compensation

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    Although most mechanized forestry work relies heavily on cranes for handling logs along the supply chain, there has been little research on how to improve cranes design. In addition, the available research has mainly focused on improving current designs, so there is a lack of application of modern methods for designing cranes with improved efficiency. This paper analyzes how a mechanical engineering design method, known as gravity compensation, can be used to make a new generation of highly energy efficient forestry cranes. To introduce this design approach, a standard forwarder crane with two booms is used as a model system on which to apply gravity compensation concepts. The design methodology follows a procedure based on physics and mathematical optimization, with the objective of minimizing the energy needed to move the crane by using gravity compensation via counterweights. To this end, we considered to minimize mechanical power, because this quantity relates to how fuel and hydraulic fluid are converted into mechanical motion. This analysis suggests that using gravity compensation could reduce energy consumption due to crane work by 27%, at the cost of increasing the crane total mass by 57%. Thus, the original crane mass of 559 kg increases to 879 kg after applying gravity compensation with counterweights. However, overall reductions in energy consumption would depend on both the crane work and the extraction distance. The greater the extraction distance, the lower the total savings. However, energy consumption savings of around 2% could be achieved even with an extraction distance of 1 km. From a design perspective, this study emphasized the need to consider gravity compensation in the design philosophy of forestry cranes, not only for its ability to minimize energy consumption, but also due to all the inherited properties it provides. This initial study concludes that designing cranes with a combination of gravity compensation concepts could yield a new generation of highly energy efficient cranes with energy savings exceeding those reported here

    Exploring the Design of Highly Energy Efficient Forestry Cranes using Gravity Compensation

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    Although most mechanized forestry work relies heavily on cranes for handling logs along the supply chain, there has been little research on how to improve cranes design. In addition, the available research has mainly focused on improving current designs, so there is a lack of application of modern methods for designing cranes with improved efficiency.This paper analyzes how a mechanical engineering design method, known as gravity compensation, can be used to make a new generation of highly energy efficient forestry cranes. To introduce this design approach, a standard forwarder crane with two booms is used as a model system on which to apply gravity compensation concepts. The design methodology follows a procedure based on physics and mathematical optimization, with the objective of minimizing the energy needed to move the crane by using gravity compensation via counterweights. To this end, we considered to minimize mechanical power, because this quantity relates to how fuel and hydraulic fluid are converted into mechanical motion.This analysis suggests that using gravity compensation could reduce energy consumption due to crane work by 27%, at the cost of increasing the crane total mass by 57%. Thus, the original crane mass of 559 kg increases to 879 kg after applying gravity compensation with counterweights. However, overall reductions in energy consumption would depend on both the crane work and the extraction distance. The greater the extraction distance, the lower the total savings. However, energy consumption savings of around 2% could be achieved even with an extraction distance of 1 km.From a design perspective, this study emphasized the need to consider gravity compensation in the design philosophy of forestry cranes, not only for its ability to minimize energy consumption, but also due to all the inherited properties it provides. This initial study concludes that designing cranes with a combination of gravity compensation concepts could yield a new generation of highly energy efficient cranes with energy savings exceeding those reported here

    Piccolo modulation of Synapsin1a dynamics regulates synaptic vesicle exocytosis

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    Active zones are specialized regions of the presynaptic plasma membrane designed for the efficient and repetitive release of neurotransmitter via synaptic vesicle (SV) exocytosis. Piccolo is a high molecular weight component of the active zone that is hypothesized to participate both in active zone formation and the scaffolding of key molecules involved in SV recycling. In this study, we use interference RNAs to eliminate Piccolo expression from cultured hippocampal neurons to assess its involvement in synapse formation and function. Our data show that Piccolo is not required for glutamatergic synapse formation but does influence presynaptic function by negatively regulating SV exocytosis. Mechanistically, this regulation appears to be calmodulin kinase II–dependent and mediated through the modulation of Synapsin1a dynamics. This function is not shared by the highly homologous protein Bassoon, which indicates that Piccolo has a unique role in coupling the mobilization of SVs in the reserve pool to events within the active zone

    Isotopic niche partitioning in two sympatric howler monkey species

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    ObjectivesEcological similarity between species can lead to interspecific trophic competition. However, when ecologically similar species coexist, they may differ in foraging strategies and habitat use, which can lead to niche partitioning. As the body tissues of consumers contain a stable isotope signature that reflects the isotopic composition of their diet, stable isotope analysis is a useful tool to study feeding behavior. We measured the isotopic niche width, which is a proxy for trophic niche width, of mantled (Alouatta palliata) and black (A. pigra) howler monkeys. Specifically, studied populations in allopatry and sympatry to assess whether these species showed niche partitioning.Materials and MethodsBetween 2008 and 2012, we collected hair samples from 200 subjects (113 black and 87 mantled howler monkeys) and used continuous flow isotope ratio mass spectrometry to estimate ή13C and ή15N. We described the isotopic niche width of each species in allopatry and sympatry with the Bayesian estimation of the standard ellipse areas.ResultsIn allopatry, isotopic niche width and isotopic variation were similar in both species. In sympatry, black howler monkeys had a significantly broader isotopic niche, which was mainly determined by high ή15N values, and included the majority of mantled howler monkeys’ isotopic niche. The isotopic niche of mantled howler monkeys did not differ between sympatry and allopatry.ConclusionsThe coexistence of these ecologically similar species may be linked to trophic niche adjustments by one species, although the particular features of such adjustments (e.g., dietary, spatial, or sensory partitioning) remain to be addressed.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/155926/1/ajpa24028.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/155926/2/ajpa24028_am.pd

    Design, rapid manufacturing and modeling of a reduced-scale forwarder crane with closed kinematic chain

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    Forestry cranes are of paramount importance in forestry operations, so considerable efforts have been carried out to improve their performance in recent years. However, all these efforts have focused on automation technology, leaving aside other alternatives for improvement. Among these alternatives is model-based design, which has the potential to be game-changing for the forest industry. Because research on model-based design is almost non-existent for forestry cranes, there are many gaps that should be filled before presenting improved designs of forestry cranes. The purpose of this article is to fill two of those gaps: (1) the high cost-benefit ratio and safety concerns when testing new designs, components or algorithms in industrial-scale forestry cranes and (2) the dynamic modeling of forestry cranes as mechanical systems with closed kinematic chain. Under these premises, this article first presents a reduced-scale platform resembling a forwarder crane with closed-kinematic chain, where the components of the mechanical structure are manufactured with 3D printing technology, and second, the modeling and experimental validation of the reduced-scale forwarder, where the closed kinematic chain is considered as a system of multiple constrained open kinematic chains. For the experimental validation, a comparison between both experimental and simulation results is presented. Results presented in this article broaden the options to design and test new concepts and/or technology to improve forestry cranes performance

    Biological aspects of little tunny Euthynnus alletteratus from Spanish and Portuguese waters.

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    This study provides information on some biological aspects of Euthynnus alletteratus from the western Mediterranean (Spanish coast) and in the Atlantic Ocean (south of Iberian Peninsula). A total of 1266 individuals were measured between 2003 and 2017. The L-W relationship was calculated with W equal to 0.01242 FL3.058 . Histological analysis of the ovaries and the monthly variation of the gonadosomatic index for both sexes suggested that the spawning season for Euthynnus alletteratus in the western Mediterranean Sea takes place from June to August. The lengths at first maturity (L50) were estimated to be 50.1 cm and 43.4 cm FL for female and male, respectively. Age at first maturity (A50) was calculated

    Macroscopic and microscopic maturity stages. living working document for small tuna species.

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    Maturity ogives are usually estimated using different methods, including macroscopical and microscopical maturity data. Differences in maturity ogives estimations are found for species and by area/stock. So those differences may be a consequence of the use of different methodological techniques (criteria) or due to different spawning tactics. Taking this into account is essential to guarantee that the maturity criteria for each species are consistent across the laboratories and countries involved in stock assessment. The objective of this document is to show a large amount of detailed photos (macro and microphotographs) of the different gonad stages of Auxis rochei, Sarda sarda and Euthynnus alletteratus, for females and males, which will be an enhancement to the descriptions of maturity stages given in the maturity tables
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