Explore the vast range of titles available.

The Asian Clam, Corbicula fluminea (O.F. Müller, 1774), is a high-risk invasive species in Mexico. The first record for the country dates back to 1969, and by 2024 its presence had been documented in 26 of the 32 Mexican states. In June 2025, the presence of C. fluminea was detected in the San Ignacio oasis, which has potential repercussions for endemic species there and highlights the urgent need to implement a control and eradication program for C. fluminea in the San Ignacio oasis. Monitoring of nearby oases is also necessary.

Estimating the population of burrow-nesting seabirds is a challenging task, as human presence in the colony creates disturbances and can damage burrows and occupants. Here, we present a novel method using aerial photographs taken with Unmanned Aerial Vehicles (UAVs) to estimate the population size of a burrow-nesting seabird, the Black-vented Shearwater (Puffinus opisthomelas), on Natividad Island, Mexico. Our results provide a census of burrows in the colony, with very low detection error (5.6%). This is greater accuracy compared to other methods based on extrapolating results from sample plots to total colony area. We then combined this burrow census with ground truth data on occupancy to estimate population size. We obtained a population estimate of 37,858 and 46,322 breeding pairs for 2016 and 2017 respectively. The proposed method provides a cost effective and repeatable approach for monitoring numbers of burrows occupied in a colony, thereby enabling easier and faster estimates of population trends. We suggest this method can be valid for other burrow-nesting species in habitats without dense vegetation cover.

Background There is controversy regarding the treatment of symptomatic synovial cysts, specifically, the need for a concomitant fusion when surgical resection of the synovial cysts is required. We present a retrospective review of a series of patients treated for symptomatic synovial cysts of the lumbar region during the last 20 years by a single surgeon, analyzing the current available literature. Methods Retrospective review. The same surgical technique was applied to all patients. Demographic, clinical, surgical data and synovial cyst recurrence rate were recorded. Postoperative results reported by patients were documented according to the McNab score. Results Sixty nine subjects, with mean follow-up of 7.4 years. 62% (43) were female, with a mean 57.8 years at the time of surgery. In 91.3% (63), the primary management was conservative for a minimum period of 3 months. All subjects underwent surgery due to the failure of conservative treatment. The segment most operated on was L4–L5 (63.77%). 91.3% (63) of the sample reported excellent and good and 6 subjects (8.6%) fair or poor results. There was no evidence of synovial cysts recurrence at the operated level. Conclusion In symptomatic synovial cysts, it seems that conservative treatment is only effective in a limited number of patients and in the short term. Thus, the recommendation of a surgical indication should proceed as soon as the conservative management fails to result in significant symptom relief. Based on our results, we recommend, together with the resection of the cyst, the instrumentation of the segment to avoid its recurrence and the management of axial pain.

Human exploitation has been a major driver of marine turtle population declines, particularly affecting naturally scarce species such as the pantropical hawksbill turtle. Although hawksbill sea turtles have been documented in the Gulf of California since the early 20th century, data on their historical demography during periods of high exploitation in this region are nonexistent. We investigated the size structure of hawksbill turtles from the Western Central Gulf of California by examining a unique sample of decorative taxidermies, corresponding to 31 specimens captured during fishing operations near Santa Rosalía, Baja California Sur, Mexico, between 1980 and 1990. An analysis of the curved carapace measures revealed a length range (nuchal notch to posterior of supracaudals) of 29.5–59.5 cm (mean = 38.75 ± 6.67 cm) and a width range of 25.0–51.5 cm (mean = 33.63 ± 5.66 cm), with 87% of specimens having lengths between 30 and 45 cm. Based on the carapace length measurements, we estimated the ages to be between 7 and 20 years, indicating that the population included juveniles. Our findings provide baseline data for an understudied period and region, suggesting that this area previously served as an important juvenile habitat. These results contribute essential historical demographic information for conservation planning.

The paper presents a complete value chain for the use of green hydrogen in a port facility. The main objective was to propose the sizing of the main components that make up green hydrogen to ensure the supply of 1 MWe in replacing the diesel generator. The energy demand required for the port was determined by establishing the leading small and large-scale conventional energy-consuming equipment. Hence, 60 kgH2 was required to ensure the power supply. The total electrical energy to produce all the hydrogen was generated from photovoltaic solar energy, considering three-generation scenarios (minimum, maximum and the annual average). In all cases, the energy supply in the electrolyzer was 3.08 MWe. In addition, the effect of generating in the port facility using a diesel generator and a fuel cell was compared. The cost of 1 kgH2 could be 4.09 times higher than the cost of 1 L of diesel, meaning that the output kWh of each system is economically similar. In addition, the value of electrical energy through a Power Purchase Agreement (PPA) was a maximum of 79.79 times the value of a liter of diesel. Finally, the Levelized Cost of Energy (LCOE) was calculated for two conditions in which the MWe was obtained from the fuel cell without and with the photovoltaic solar plant.

We propose a new type of neural adaptive control via dynamic neural networks. For a class of unknown nonlinear systems, a neural identifier-based feedback linearization controller is first used. Dead-zone and projection techniques are applied to assure the stability of neural identification. Then four types of compensator are addressed. The stability of closed-loop system is also proven.

Purpose – This paper aims to address a new iterative tuning method of PID control for robot manipulators. Design/methodology/approach – This tuning method uses several properties of the robot control, such as any PD control can stabilize a robot in regulation case, the closed-loop system of PID control can be approximated by a linear system, the control torque to the robot manipulator is linearly independent of the robot dynamic. Findings – Compared with the other PID tuning methods, this novel method is simple, systematic, and stable. The transient properties of this PID control are better than the other normal PID controllers. Originality/value – In this paper, a new systematic tuning method for PID control is proposed. The paper applies this method on an upper limb exoskeleton, and real experiment results give validation of our PID tuning method.

In Northwestern Mexico, approximately 40 breeding species of seabirds have been reported, with several threats (e.g., invasive species introduction and habitat loss) affecting the viability of their populations. As such, it is necessary to take action for their protection. To prioritize conservation activities, 119 reports (governamental agency monitoring programs, grey literature, and scientific literature) were analyzed for research and monitoring results from 1922-2018 (93 of 119 published after 1990) and ranked the different islands (91 sites, including archipelagos with multiple islands) based on their breeding seabird communities (35 species in 11 seabird families, including 7 endemic breeders). For the ranking exercise, three criteria were considered: conservation category, preferred habitat, and foraging guild for each species. Taking into consideration the breeding species on each island, an index to rank the islands was created. Ten islands or archipelagos have high conservation priority (index score > 10 = high priority; mean index = 4.7, median = 5.0, max = 17.9, n = 91), and the most important are: Revillagigedo and San Benito archipelagos, Coronado, San Lorenzo, and Natividad Islands. It is necessary to use new tools and techniques to determine populations' sizes and trends and to create a baseline to compare with future studies. Furthermore, many of the species breeding or feeding in the Mexican Economic Exclusive Zone migrate to other latitudes, elevating the conservation problem to an international scale.

Marbled Godwits (Limosa fedoa) do not present obvious sexual dimorphism, although females are known to be slightly larger than males, on average. During the nonbreeding seasons between August 2007 and April 2009, a noninvasive technique was tested that might permit phenotypic identification of sex in a large sample of individuals from the most important wintering area, Guerrero Negro, México. Blood samples (n = 577) were used for molecular sexing. For phenotypic sexing, culmen length was selected because it had the greatest sexual dimorphism. A normal distribution curve for culmen length of each sex and the overlapping area between the two curves was calculated and used to minimize the probability of error in identifying the sex of each individual. Using the criterion that males had a culmen length ≤ 106 mm and females ≥ 108 mm, the sex of 96.4% of the individuals would be correctly identified, 2.8% would be regarded as indeterminate and 0.8% would be sexed erroneously. A discriminant analysis using bill length and other commonly used phenotypic measurements did not improve success in predicting sex. The results indicate that culmen length is a useful measure for sex determination in Marbled Godwit. Identification of the sex of Marbled Godwits in the field offers new possibilities to study life histories of both sexes. In Guerrero Negro, the sex ratio of Marbled Godwits was heavily male-biased biased (2:1), suggesting latitudinal segregation by sex.

Many shorebirds exhibit within- and among-year site fidelity during their annual cycle. Little is known, however, about the migration ecology of Red Knots (Calidris canutus) that migrate along the Pacific Flyway and occur in Washington in numbers that exceed counts elsewhere on the flyway. At two large estuaries in coastal Washington, Grays Harbor and Willapa Bay, we searched for and recorded the locations of Red Knots (N = 547) that had been individually marked with leg flags at their wintering grounds in Baja California Sur, Mexico, during the period from October 2006 to April 2009. In 2010, we resighted 43 Red Knots at Grays Harbor and Willapa Bay that had been observed at these sites in previous years, primarily in 2009. We found a high degree of site fidelity between years, with birds observed in 2010 more likely to return to the same stopover site used in 2009 than to switch stopover sites. For knots that did not switch estuaries between years, the median nearest distance between locations where individuals were observed between years was 1.4 km at Grays Harbor and 0.6 km at Willapa Bay. Our results provide the first evidence of stopover site fidelity by Red Knots of the roselaari subspecies. Fidelity occurred at three spatial scales: coastal Washington, the two estuaries where we conducted our study, and specific mudflat areas within the estuaries. Because our study sites support high populations of bivalves, Red Knots may be returning to the same areas in subsequent years to exploit what we suspect is a predictable food resource. The abundance of Red Knots and high degree of site fidelity suggest that our study sites in Grays Harbor and Willapa Bay are important for the conservation of this species on the Pacific Flyway. No hay información sobre la fidelidad de los playeros rojizos del Pacífico (Calidris canutus roselaari) a las costas de Washington, pese a que en ellas sus números superan los de otras partes de la ruta migratoria. Investigaciones de fidelidad al sitio permitirán contextualizar la importancia de los estuarios de Washington para esta subespecie en su migración al norte. En las primaveras de 2009 y 2010 registramos, en Grays Harbor y Bahía Willapa, playeros rojizos marcados individualmente con banderas en las patas (N = 547). Las aves se marcaron en Baja California Sur, México, su principal zona de invernación, entre octubre de 2006 y abril de 2009. En 2010 observamos 43 playeros rojizos previamente registrados, sobre todo en 2009. Encontramos una fidelidad interanual alta al sitio, con mayor probabilidad de reobservar a las aves en el mismo sitio en ambos ańos. Además la distancia entre las localidades donde registramos a los individuos en los dos años, sugiere una fidelidad alta a zonas específicas dentro de los sitios de escala. La distancia media entre las localidades de observación (diferentes años), fue de 1.4 km para Grays Harbor y 0.6 km para Bahía Willapa. Nuestros resultados proporcionan la primera evidencia de fidelidad a un sitio de paso de esta subespecie. Así la fidelidad ocurre a tres escalas espaciales: la costa de Washington, los dos estuarios y áreas específicas dentro de los humedales. Esta fidelidad se relaciona probablemente con las grandes poblaciones de bivalvos que existen en el área, los cuales, presumimos, representan un recurso predecible para las aves. La abundancia de playeros rojizos y el alto grado de fidelidad al lugar sugieren que nuestros sitios de estudio (Grays Harbor y Bahía Willapa) son importantes para la conservación de estas aves.