Exploring tear viscosity with quartz crystal microbalance technology.

Tear viscosity is a critical property affecting tear distribution and ocular surface stability. While not widely established as a primary diagnostic marker, deviations from normal viscosity can impact ocular health, potentially contributing to conditions such as dry eye syndrome. Despite their importance, traditional viscometers require sample volumes that are not feasible to use with tear volume. This research introduces a novel Quartz Crystal Microbalance (QCM)-based method for tear viscosity measurement, offering a viscometer prototype that operates with minimal sample volumes. Human tear samples, solutions used in artificial eye drops, and various commercial eye drop brands were evaluated. Results show that the QCM method aligns with established viscosity ranges. The average viscosity of healthy human tears was found to be 1.73 ± 0.61 cP, aligning with the typical range of 1-10 cP. Variability in the viscosities of eye drop can be attributed to differences in their chemical compositions. The QCM method offers benefits such as reduced sample consumption and rapid results, enhancing understanding of tear dynamics for ocular health. Further research with larger sample sizes is needed to establish normative viscosity values in healthy individuals and those with dry eye syndrome, which is crucial for validating the device's clinical efficacy.

Patient interest in and clinician reservations on polygenic embryo screening: a qualitative study of stakeholder perspectives.

PURPOSE: We explored and compared perspectives of reproductive endocrinology and infertility specialists (REIs) and in vitro fertilization (IVF) patients regarding polygenic embryo screening (PES), a new type of preimplantation screening that estimates the genetic chances of developing polygenic conditions and traits in the future. METHODS: Qualitative thematic analysis of semi-structured interviews with US-based REIs and IVF patients. RESULTS: Clinicians and patients often held favorable views of screening embryos for physical or psychiatric conditions, though clinicians tended to temper their positive attitudes with specific caveats. Clinicians also expressed negative views about screening embryos for traits more frequently than patients, who generally held more positive views. Most clinicians were either unwilling to discuss or offer PES to patients or were willing to do so only under certain circumstances, while many patients expressed interest in PES. Both stakeholder groups envisioned multiple potential benefits or uses of PES and raised multiple potential, interrelated concerns about PES. CONCLUSION: A gap exists between clinician and patient attitudes toward PES; clinicians generally maintained reservations about such screening and patients indicated interest in it. Clinicians and patients sometimes imagined using PES to prepare for the birth of a predisposed or "affected" individual-a rationale that is often associated with prenatal testing. Many clinicians and patients held different attitudes depending on what is specifically screened, despite the sometimes blurry distinction between conditions and traits. Considerations raised by clinicians and patients may help guide professional societies in developing guidelines to navigate the uncertain terrain of PES.

Vision-Related Quality of Life after Cataract Surgery in West Africa.

PURPOSE: To study vision related quality of life (VRQoL) before and after a massive cataract campaign in West Africa and the relationship with visual indicators. METHODS: All the patients who received cataract surgery in Burkina Faso during a blindness prevention campaign were examined. VRQoL was assessed using a modified version of the WHO/PBD VF20. The questionnaire was changed to reflect the socioeconomic and local culture. Patients were interviewed by local interviewers before and three months after surgery. A quality of life related to vision index (QoL-RVI) was calculated. RESULTS: A total of 305 patients underwent cataract extraction in at least one eye, of these, a total of 196 (64%) completed the study. Mean age was 61.97 ± 14.39 years. The majority of eyes had poor visual acuity (VA<20/200, log MAR: 1.0) preoperatively (88.70%) with a mean VA of logMAR 2.17 ± 0.70 (20/2000) which improved to 0.86 ± 0.64 LogMAR (20/150) 3 months after cataract surgery. QoL-RVI improved postoperatively in 90.2% of patients, did not change in 3.1% and was worse in 6.7%. Statistically significant differences were detected (Wilcoxon test p <0.05) for all items tested before and after surgeries. Correlations for the patients after operations showed that there was a statistically significant relation between a global estimated QoL-RVI and the VA previous to the surgery (-0.196 p=0.014), regarding the same index and the VA after the procedures (-0,35 p=0,00018). CONCLUSION: Cataract surgery increases the quality of life of patients living in a developing country such as Burkina Faso and the improvement correlates with the recovery of the visual acuity.

OBJECTIF: Étudier la qualité de vie liée à la vision (VRQoL) avant et après une campagne massive contre la cataracte en Afrique de l'Ouest et la relation avec les indicateurs visuels. MÉTHODES: Tous les patients qui ont été opérés de la cataracte au Burkina Faso pendant une campagne de prévention de la cécité ont été examinés. La VRQoL a été évaluée en utilisant une version modifiée du VF20 de l'OMS/PBD. Le questionnaire a été modifié pour refléter la culture socio-économique et locale. Les patients ont été interrogés par des enquêteurs locaux avant et trois mois après la chirurgie. Un indice de qualité de vie liée à la vision (QoL-RVI) a été calculé. RÉSULTATS: Un total de 305 patients ont subi une extraction de la cataracte dans au moins un œil, parmi ceux-ci, un total de 196 (64%) ont terminé l'étude. L'âge moyen était de 61,97 ± 14,39 ans. La majorité des yeux avaient une mauvaise acuité visuelle (AV<20/200, logMAR : 1,0) en préopératoire (88,70%) avec une VA moyenne de logMAR 2,17 ± 0,70 (20/2000) qui s'est améliorée à 0,86±0,64 LogMAR (20/150) 3 mois après la chirurgie de la cataracte. La QoL-RVI s'est améliorée après l'opération chez 90,2% des patients, n'a pas changé chez 3,1% et s'est aggravée chez 6,7%. Des différences statistiquement significatives ont été détectées (test de Wilcoxon p <0,05) pour tous les éléments testés avant et après les opérations. Les corrélations pour les patients après les opérations ont montré qu'il y avait une relation statistiquement significative entre une estimation globale de la QoL-RVI et l'AV avant l'opération (-0,196 p=0,014), concernant le même indice et l'AV après les procédures (-0,35 p=0,00018). CONCLUSION: La chirurgie de la cataracte augmente la qualité de vie des patients vivant dans un pays en voie de développement comme le Burkina Faso et cette amélioration est corrélée avec la récupération de l'acuité visuelle. Mots clés: Qualité de Vie, Cataracte, Cécité, Afrique de l'Ouest.

Quartz crystal Microbalance with dissipation monitoring for biomedical applications: Open source and low cost prototype with active temperature control.

Advances in sensors have revolutionized the biomedical engineering field, having an extreme affinity for specific analytes also providing an effective, real-time, point-of-care testing for an accurate diagnosis. Quartz Crystal Microbalance (QCM) is a well-established sensor that has been successfully applied in a broad range of applications to monitor and explore various surface interactions, in situ thin-film formations, and layer properties. This technology has gained interest in biomedical applications since novel QCM systems are able to work in liquid media. QCM with dissipation monitoring (QCM-D) is an expanded version of a QCM that measures changes in damping properties of adsorbed layers thus providing information on its viscoelastic nature. In this article, an open source and low cost QCM-D prototype for biomedical applications was developed. In addition, the system was validated using different Polyethylene Glycol (PEG) concentrations due to its importance for many medical applications. The statistics show a bigger dissipation of the system as the fluid becomes more viscous, also having a very acceptable sensibility when temperature is controlled.

[Seroprevalence of Toxoplasma gondii in students with occupational risk]. / Seroprevalencia de Toxoplasma gondii en estudiantes con riesgo ocupacional.

BACKGROUND: Toxoplasmosis is a disease that results from infection with the Toxoplasma gondii parasite, one of the world's most common parasites. The zoonotic infection usually occurs by eating undercooked contaminated meat or by contact with contaminated cat feces. A few studies of toxoplasmosis in healthy and immuno-compromised persons were done in Chile, but investigations related to occupational risk groups, such as Veterinary Medicine students were not studied. AIM: Determine the seroprevalence for T. gondii in Veterinary Medicine students at a university located in the center-south of the country, and evaluated to association with intrinsic variables. METHODS: Peripheral blood samples were taken from 74 veterinary students from a university in south-central Chile. Immunoassay with sequential chemiluminescent was used as diagnostic technique. RESULTS: Of the total number of students, 16 were seropositive, which is equivalent to 21.6%, the largest number of seropositive students was female (75%), they were in the age range between 24 and 26 years of age (43.7%), all consumed meat and vegetables (100%) and collected pet cat feces without protection 50 (68,7%). CONCLUSIONS: The results obtained show the presence of antibodies against T. gondii in Veterinary Medicine students. To the authors' knowledge, it is the first serological study for toxoplasmosis performed in university students of Veterinary Medicine in Chile.

Neuroleptic malignant syndrome in a postoperative patient: A case report.

Neuroleptic malignant syndrome is a rare medical emergency associated with the use of antipsychotics and other antidopaminergic drugs. There is no specific test, and diagnosis is based on high clinical suspicion and good differential diagnosis. A clinical picture consistent with hyperthermia, muscle rigidity, altered level of consciousness, together with signs of rhabdomyolysis in analytical studies and a history of taking neuroleptic drugs are the key elements in the detection of this entity. Due to its low incidence and potential mortality, it is essential to publish case reports of neuroleptic malignant syndrome in order to raise awareness of this entity and facilitate diagnostic suspicion when encountering a patient with compatible symptoms. The following is the case of a 79 year old patient with chronic alcohol consumption as the only history of interest, who was given a single dose of haloperidol after an episode of delirium in the postoperative period of conventional trauma surgery. She subsequently developed a picture of progressive deterioration of the level of consciousness, diaphoresis, generalized muscle rigidity, hyperthermia, together with severe metabolic acidosis, hyperlacticaemia, rhabdomyolysis, hypertransaminasemia and hypocalcemia. After ruling out other entities compatible with the clinical picture, neuroleptic malignant syndrome was given as the main diagnostic hypothesis. Diagnosis was confirmed after clinical and analytical improvement following treatment with dantrolene. The patient was discharged from hospital with no sequelae a few days after onset of the condition.

Seroprevalencia de Toxoplasma gondii en estudiantes con riesgo ocupacional / Seroprevalence of Toxoplasma gondii in students with occupational risk

INTRODUCCIÓN: La toxoplasmosis es una enfermedad zoonótica cuyo contagio se produce por vía oral por ingestión de quistes al consumir carne contaminada o al tener contacto con heces de felinos contaminadas con ooquistes. Con menor frecuencia, se adquiere por transmisión vertical o por trasplante de órganos infectados. En Chile, existen estudios serológicos en personas sanas e inmunodeprimidas, pero no en grupos de riesgo ocupacional, como son los estudiantes de Medicina Veterinaria. OBJETIVO: Determinar la seroprevalencia para T. gondii en estudiantes de Medicina Veterinaria de una universidad ubicada en el centro-sur del país, y ver su asociación con variable intrínsecas. MÉTODOS. Se tomaron muestras de sangre a 74 estudiantes de una universidad del centro-sur de Chile. Se determinó la presencia de anticuerpos específicos clase IgG contra Toxoplasma gondii mediante la técnica de inmunoanálisis por quimioluminiscencia en fase solida secuencial. RESULTADOS. Del total de alumnos, 16 fueron seropositivos lo que equivale a 21,6%, el mayor número de estudiantes seropositivos fue de sexo femenino (75%), se encontraban en el rango etario entre 24 y 26 años de edad (43,7%), todos consumían carne y verduras (100%) y realizaban la recolección de heces de gatos sin protección 50 (68,7%). CONCLUSIONES. Los resultados obtenidos demuestran la presencia de anticuerpos contra T. gondii en alumnos de Medicina Veterinaria. Según el conocimiento de los autores, es el primer estudio serológico para toxoplasmosis realizado en estudiantes universitarios de Medicina Veterinaria en Chile.

BACKGROUND: Toxoplasmosis is a disease that results from infection with the Toxoplasma gondii parasite, one of the world's most common parasites. The zoonotic infection usually occurs by eating undercooked contaminated meat or by contact with contaminated cat feces. A few studies of toxoplasmosis in healthy and immuno-compromised persons were done in Chile, but investigations related to occupational risk groups, such as Veterinary Medicine students were not studied. AIM: Determine the seroprevalence for T. gondii in Veterinary Medicine students at a university located in the center-south of the country, and evaluated to association with intrinsic variables. METHODS: Peripheral blood samples were taken from 74 veterinary students from a university in south-central Chile. Immunoassay with sequential chemiluminescent was used as diagnostic technique. RESULTS. Of the total number of students, 16 were seropositive, which is equivalent to 21.6%, the largest number of seropositive students was female (75%), they were in the age range between 24 and 26 years of age (43.7%), all consumed meat and vegetables (100%) and collected pet cat feces without protection 50 (68,7%). CONCLUSIONS: The results obtained show the presence of antibodies against T. gondii in Veterinary Medicine students. To the authors' knowledge, it is the first serological study for toxoplasmosis performed in university students of Veterinary Medicine in Chile.

Polygenic embryo screening: four clinical considerations warrant further attention.

Recent advances in developing polygenic scores have made it possible to screen embryos for common, complex conditions and traits. Polygenic embryo screening (PES) is currently offered commercially, and though there has been much recent media and academic coverage, reproductive specialists' points of view have not yet been prominent in these discussions. We convened a roundtable of multidisciplinary experts, including reproductive specialists to discuss PES and its implications. In this Opinion, we describe four clinically relevant issues associated with the use of PES that have not yet been discussed in the literature and warrant consideration.

An introduction to the sources, fate, occurrence and effects of endocrine disrupting chemicals released into the environment.

Many classes of compounds are known or suspected to disrupt the endocrine system of vertebrate and invertebrate organisms. This review of the sources and fate of selected endocrine disrupting chemicals (EDCs) in the environment includes classes of compounds that are "legacy" contaminants, as well as contaminants of emerging concern. EDCs included for discussion are organochlorine compounds, halogenated aromatic hydrocarbons, brominated flame retardants, per- and polyfluoroalkyl substances, alkylphenols, phthalates, bisphenol A and analogues, pharmaceuticals, drugs of abuse and steroid hormones, personal care products, and organotins. An exhaustive survey of the fate of these contaminants in all environmental media (e.g., air, water, soil, biota, foods and beverages) is beyond the scope of this review, so the priority is to highlight the fate of EDCs in environmental media for which there is a clear link between exposure and endocrine effects in humans or in biota from other taxa. Where appropriate, linkages are also made between the fate of EDCs and regulatory limits such as environmental quality guidelines for water and sediments and total daily intake values for humans.

Methods for the analysis of endocrine disrupting chemicals in selected environmental matrixes.

Endocrine disrupting chemicals (EDCs) are heterogenous in structure, chemical and physical properties, and their capacity to partition into various environmental matrixes. In many cases, these chemicals can disrupt the endocrine systems of vertebrate and invertebrate organisms when present at very low concentrations. Therefore, sensitive and varied analytical methods are required to detect these compounds in the environment. This review summarizes the analytical methods and instruments that are most used to monitor for EDCs in selected environmental matrixes. Only those matrixes for which there is a clear link between exposures and endocrine effects are included in this review. Also discussed are emerging methods for sample preparation and advanced analytical instruments that provide greater selectivity and sensitivity.

Neuroleptic malignant syndrome in a postoperative patient: a case report. / Síndrome neuroléptico maligno en paciente postoperada: a propósito de un caso.

Neuroleptic malignant syndrome is a rare medical emergency associated with the use of antipsychotics and other antidopaminergic drugs. There is no specific test, and diagnosis is based on high clinical suspicion and good differential diagnosis. A clinical picture consistent with hyperthermia, muscle rigidity, altered level of consciousness, together with signs of rhabdomyolysis in analytical studies and a history of taking neuroleptic drugs are the key elements in the detection of this entity. Due to its low incidence and potential mortality, it is essential to publish case reports of neuroleptic malignant syndrome in order to raise awareness of this entity and facilitate diagnostic suspicion when encountering a patient with compatible symptoms. The following is the case of a 79 year old patient with chronic alcohol consumption as the only history of interest, who was given a single dose of haloperidol after an episode of delirium in the postoperative period of conventional trauma surgery. She subsequently developed a picture of progressive deterioration of the level of consciousness, diaphoresis, generalized muscle rigidity, hyperthermia, together with severe metabolic acidosis, hyperlacticaemia, rhabdomyolysis, hypertransaminasemia and hypocalcemia. After ruling out other entities compatible with the clinical picture, neuroleptic malignant syndrome was given as the main diagnostic hypothesis. Diagnosis was confirmed after clinical and analytical improvement following treatment with dantrolene. The patient was discharged from hospital with no sequelae a few days after onset of the condition.

Proximal composition and fatty acid profile of Hemigrapsus crenulatus (H. Milne Edwards, 1837) as one of the main foods of "patagonian blenny"Eleginops maclovinus (Cuvier, 1830) / Composição proximal e perfil de ácidos graxos de Hemigrapsus crenulatus (H. Milne Edwards, 1837) como um dos principais alimentos da "blenny patagônica" Eleginops maclovinus (Cuvier, 1830)

Abstract The Patagonian blenny (Eleginops maclovinus) is species endemic to South America with physiological characteristics that would facilitate its incorporation into Chilean aquaculture. However, there is currently no specific artificial food that can be used to raise E. maclovinus. In light of this problem, this study describes the proximal composition and fatty acid profile of the crab Hemigrapsus crenulatus, one of the main foods of E. maclovinus. The purpose of the study is to serve as basic information for the development of a specific artificial diet for juveniles of this fish species. The proximal analysis of the complete body of H. crenulatus indicates that it is mainly composed of ash (35.9%), proteins (32.2%), glucides (19.8%) and minor lipids (3.6%). The fatty acid profile is 40.7% PUFAs, 29.7% MUFAs and 29.5% SAFAs, and the most abundant acids are Eicosapentaenoic (18.8%), Oleic (6.8%) and Palmitic (16.6%), respectively. H. crenulatus has highest level of proteins, lipids and PUFAs among the species of the Brachyura infraorder.

Resumo O "blenny da patagônia" (Eleginops maclovinus) é uma espécie endêmica da América do Sul, com características fisiológicas que facilitariam sua incorporação na aquicultura chilena. No entanto, atualmente não há alimento artificial específico que possa ser usado para criar E. maclovinus. Diante desse problema, este estudo descreve a composição proximal e o perfil de ácidos graxos do caranguejo Hemigrapsus crenulatus, um dos principais alimentos de E. maclovinus. O objetivo do estudo é servir como informação básica para o desenvolvimento de uma dieta artificial específica para espécies juvenis desse peixe. A análise proximal do corpo completo de H. crenulatus indica que ele é composto, principalmente, de cinzas (35,9%), proteínas (32,2%), glicídios (19,8%) e lipídios menores (3,6%). O perfil de ácidos graxos é 40,7% PUFA, 29,7% MUFA e 29,5% SAFA, e os ácidos mais abundantes são eicosapentaenoico (18,8%), oleico (6,8%) e palmítico (16,6%), respectivamente. H. crenulatus possui o mais alto nível de proteínas, lipídios e PUFAs entre as espécies da infraordem de Brachyura.

Entropy, purity and optical hysteresis in markovian optical modes.

We describe the synthesis of optical modes whose axial structure follows a random tandem array of Bessel beams of integer order. The array follows fluctuations of Markov-chain type and the amplitude values for each beam are linked to a sequence of random vectors. As a prototype, we describe the synthesis of optical fields for Markov-chain type Ehrenfest. This process models the thermodynamic equilibrium and then it can be related to the evolution and stability of optical systems, in this way, it offers a similitude with partially coherent processes where the coherence degree is now distributed between all the compounds of the resulting random vector. The matrix representation for the stochastic process allows incorporating entropy properties and the calculus of the purity for the optical field. This constitutes the basis to describe the interference between markovian modes. When the set of markovian modes type Ehrenfest reaches a stable configuration they become indistinguishability non-conservative optical field having associated hysteresis features. Computer simulations are presented.

Stability of focusing regions and its vortex-solitonic properties.

Focusing regions, also known as caustic regions, are the singular solutions to the amplitude function of optical fields. Focusing regions are generated by the envelope curve of a set of critical points, which can be of attractor or repulsor type. The nature of the critical point depends on the refractive index. An important property of the critical points is that they present charge-like features. When a focusing region is generated in media with a random refractive index, current-like effects appear, and the evolution of the focusing regions follows a diffusion behavior. The morphology of the focusing regions may generate vortices or "eternal solutions" of solitonic type in a nonlinear medium. Herein, the condition under which these effects occur is analyzed and experimentally corroborated.

Endoparasitic diversity from the Southern Ocean: is it really low in Antarctic fish?

The biodiversity and composition of endoparasites in fish obtained from the Antarctic and subantarctic zones are compared in this study. Several fish were collected in the summer from Antarctica (King George Island) and the Southern Pacific coast (Strait of Magellan and Almirante Montt Gulf). This database was complemented with published information on fish endoparasite communities from both zones, with specimens of fish sample size n ≥ 15. Thus, 31 fish species were analysed in this study, which altogether had 79 parasite species. Diversity indices were calculated for the parasite community of each fish species. Then they were compared between the Antarctic and subantarctic zones. Parasite species composition and host specificity (as the number of fish species used by a parasite species) were also analysed and compared between zones. The diversity indices and the abundance of parasites were significantly higher in the Antarctic than the subantarctic fish. Few parasite species (7.6%) were shared between fish from both zones, showing significant differences in parasite composition. Antarctic parasites were less host-specific than subantarctic parasites, which allowed the coexistence of several parasite species in the fish. The high parasite abundance in Antarctic fish could trigger sympatric speciation in certain parasitic lineages or the exploitation of new resources, resulting in more parasite species than those in subantarctic environments. The high abundance of Antarctic parasites implies different methods and rates of transmission than those of subantarctic parasites. In addition, more alternative fish hosts were used by the Antarctic than subantarctic parasites. This altogether indicates that host-parasite interaction dynamics significantly differ between the Antarctic and subantarctic systems.

Patient characteristics, clinical course and factors associated to ICU mortality in critically ill patients infected with SARS-CoV-2 in Spain: A prospective, cohort, multicentre study. / Características, evolución clínica y factores asociados a la mortalidad en UCI de los pacientes críticos infectados por SARS-CoV-2 en España: estudio prospectivo, de cohorte y multicéntrico.

BACKGROUND: The clinical course of COVID-19 critically ill patients, during their admission in the intensive care unit (UCI), including medical and infectious complications and support therapies, as well as their association with in-ICU mortality has not been fully reported. OBJECTIVE: This study aimed to describe clinical characteristics and clinical course of ICU COVID-19 patients, and to determine risk factors for ICU mortality of COVID-19 patients. METHODS: Prospective, multicentre, cohort study that enrolled critically ill COVID-19 patients admitted into 30 ICUs from Spain and Andorra. Consecutive patients from March 12th to May 26th, 2020 were enrolled if they had died or were discharged from ICU during the study period. Demographics, symptoms, vital signs, laboratory markers, supportive therapies, pharmacological treatments, medical and infectious complications were reported and compared between deceased and discharged patients. RESULTS: A total of 663 patients were included. Overall ICU mortality was 31% (203 patients). At ICU admission non-survivors were more hypoxemic [SpO2 with non-rebreather mask, 90 (IQR 83 to 93) vs. 91 (IQR 87 to 94); P<.001] and with higher sequential organ failure assessment score [SOFA, 7 (IQR 5 to 9) vs. 4 (IQR 3 to 7); P<.001]. Complications were more frequent in non-survivors: acute respiratory distress syndrome (ARDS) (95% vs. 89%; P=.009), acute kidney injury (AKI) (58% vs. 24%; P<10-16), shock (42% vs. 14%; P<10-13), and arrhythmias (24% vs. 11%; P<10-4). Respiratory super-infection, bloodstream infection and septic shock were higher in non-survivors (33% vs. 25%; P=.03, 33% vs. 23%; P=.01 and 15% vs. 3%, P=10-7), respectively. The multivariable regression model showed that age was associated with mortality, with every year increasing risk-of-death by 1% (95%CI: 1 to 10, P=.014). Each 5-point increase in APACHE II independently predicted mortality [OR: 1.508 (1.081, 2.104), P=.015]. Patients with AKI [OR: 2.468 (1.628, 3.741), P<10-4)], cardiac arrest [OR: 11.099 (3.389, 36.353), P=.0001], and septic shock [OR: 3.224 (1.486, 6.994), P=.002] had an increased risk-of-death. CONCLUSIONS: Older COVID-19 patients with higher APACHE II scores on admission, those who developed AKI grades ii or iii and/or septic shock during ICU stay had an increased risk-of-death. ICU mortality was 31%.

Invariant correlated optical fields driven by multiplicative noise.

We describe the evolution of a linear transmittance when it is perturbed with multiplicative noise; the evolution is approximated through an ensemble of random transmittances that are used to generate diffraction fields. The randomness induces a competition mechanism between noise and transmittance, and it is identified through the self-correlation function. We show that the geometry of the self-correlation function is a single peak preserved in the diffraction field that can be matched with localization-like effects. To corroborate the theoretical predictions, we perform an experiment using a linear grating where the noise is approximated by a stochastic Markov chain. Experimental results are shown.

Geographic and ontogenetic variations in parasite communities of intertidal fish species from the south-eastern Pacific coast.

Parasite composition can be affected by physiological and ecological changes during host ontogeny. Intertidal fish do not travel long distances and live in the same area throughout their lifetimes, meaning that parasite communities can differ across geographic ranges. The objective of this study was to analyse the parasite communities of three fish species (Hypsoblennius sordidus, Helcogrammoides cunninghami and Scartichthys viridis) collected from the Chilean coast. The composition of parasite species was compared among host ontogenetic stages (larvae, juveniles and mature fish) and geographic areas. A total of 184 larval, 252 juveniles and 217 mature individuals were collected in the northern area (c. 24°S), and 186 larval, 192 juveniles and 112 mature individuals from the central area (c. 33°S). Ectoparasites were most prevalent in fish from the central area, whereas endoparasites were most prevalent in the northern area. The parasite species richness varied significantly between geographical areas for H. sordidus and H. cunninghami, but the parasite composition varied significantly between geographical areas for all fish species analysed. Therefore, the geographical area was the most important factor determining the parasite composition of intertidal fish species. The absence of endoparasites in fish larvae and the increased infestation in juvenile and mature fish may be explained by the shift in habitat from the water column to intertidal pools where prey abundance and availability are higher. On the other hand, hydrographic barriers affecting prey distributions may also offer an explanation as to the differences in parasite composition.

Proximal composition and fatty acid profile of Hemigrapsus crenulatus (H. Milne Edwards, 1837) as one of the main foods of "patagonian blenny"Eleginops maclovinus (Cuvier, 1830).

The Patagonian blenny (Eleginops maclovinus) is species endemic to South America with physiological characteristics that would facilitate its incorporation into Chilean aquaculture. However, there is currently no specific artificial food that can be used to raise E. maclovinus. In light of this problem, this study describes the proximal composition and fatty acid profile of the crab Hemigrapsus crenulatus, one of the main foods of E. maclovinus. The purpose of the study is to serve as basic information for the development of a specific artificial diet for juveniles of this fish species. The proximal analysis of the complete body of H. crenulatus indicates that it is mainly composed of ash (35.9%), proteins (32.2%), glucides (19.8%) and minor lipids (3.6%). The fatty acid profile is 40.7% PUFAs, 29.7% MUFAs and 29.5% SAFAs, and the most abundant acids are Eicosapentaenoic (18.8%), Oleic (6.8%) and Palmitic (16.6%), respectively. H. crenulatus has highest level of proteins, lipids and PUFAs among the species of the Brachyura infraorder.