BIRD ENTANGLEMENT AND MORTALITY BY FRUITS OF THE ZAPALLO CASPI TREE PISONIA ZAPALLO IN THE DRY CHACO, ARGENTINA

Abstract ∙ Bird entanglement by plants may be globally widespread, but it is not a frequently studied phenomenon, and records in different regions of the world are still scarce. During a short visit to the El Impenetrable National Park, Chaco province, Argentina, in October–November 2022, we recorded 15 incidental cases of birds entangled or trapped by fruits of the tree Pisonia zapallo. Our report involves 12 bird species from eight families, with a wide range of body sizes and masses. To our knowledge, this is the first documented report on this phenomenon in continental South America

Nonlinear mirror based on cross-polarized wave generation

We present a new type of nonlinear mirror based on the generation of a cross-polarized wave through a nonresonant electronic third-order process. It is characterized by a reflection coefficient that depends on the input intensity. Its behavior results from the interference between the nonlinearly generated cross-polarized wave and a /2 phase-retarded wave. This setup has a lot of advantages: it does not require any phase matching, it is achromatic and suitable for femtosecond pulses, linear losses are easily adjustable, and the overall behavior is predictable. The device has been experimentally tested using BaF 2 and YVO 4 crystals. OCIS codes: 190.0190, 230.4320, 140.4050. Nonlinear mirrors (NLMs) are known to be used for mode-locking (ML) operation in solid-state lasers and also for other applications, e.g., for pulse reshaping and compression and contrast improvement. In general, NLMs can be divided into two groups. The first group is based on ͑3͒ effects: self-induced ellipse rotation in isotropic media, 1,2 the Kerr lens effect, 3 or interference effects in an external cavity with ͑3͒ media. © 2006 Optical Society of America ͑2͒ cascaded processes. 12 Here, we introduce a new type of NLM based on the generation of a linearly polarized wave cross polarized to the input one. The cross-polarized wave (XPW) generation effect is a four-wave mixing process that depends on the anisotropy of the ͑3͒ tensor. The scheme of the XPW-based NLM is shown i

Categorización del estado de conservación de las tortugas de la República Argentina

Con la participación de nueve especialistas de diferentes instituciones de Argentina y transcurridos más de 10 años desde la primera Lista Roja de la herpetofauna de la República Argentina realizada por la Asociación Herpetológica Argentina en el año 2000, se re-categorizaron los taxones de Testudines presentes en el país incorporando nueva información taxonómica, biológica y ecológica y, aplicando correcciones metodológicas. Como resultado, de los 14 taxones de tortugas continentales y marinas, nueve quedaron incluidas en la presente Lista Roja bajo algún grado de amenaza, tres En Peligro, tres Amenazadas y tres Vulnerables, mientras que dos fueron categorizadas como No Amenazadas y tres son Insuficientemente Conocidas. En la evaluación de las tres especies de tortugas marinas, que frecuentan las costas del Mar Argentino, se homologaron las categorías con las de IUCN (2011). Respecto de la categorización anterior, se agregó la especie Phrynops geoffranus (Insuficientemente Conocida), se sinonimizaron dos especies, disminuyó el número de especies En Peligro de tres a dos y se incrementó el de Vulnerables de una a tres. Los pocos cambios resultantes de la presente categorización de las tortugas de Argentina respecto de la anterior podría reflejar la escasez de estudios realizados sobre este grupo en la última década y la necesidad de promoverlos.Through the participation of nine specialists from different institutions from all over Argentina and after more than a decade from the first Red List of threatened herpetofauna proposed by Asociación Herpetológica Argentina in 2000, we assessed the conservation status of the argentine Testudines taxa, adding the new taxonomic, biological and ecological knowledge progresses made since then as well as applying methodological changes in the former assessment. As a result from the 14 turtles taxa recognized as present in Argentina, nine were included in the actual Red List under some degree of risk (three Critically Endangered, three Endangered, three Vulnerable). From the remaining ones, three were classified as Insufficiently Known and two as Not Threatened. In the classification of the three marine turtles that are frequently found in argentine coasts we adopted the IUCN (2011) Red List criteria. In relation with the former categorization, we included a new species registered in Argentina (Phrynops geoffranus, Insufficiently Known), added two synonymies, increased from one to three the species within the Vulnerable Category and decreased from three to two the Critically Endangered species number. The few changes between the two assessments of the argentine turtle´s conservation status are due to the scarcity of new scientific contributions made to the knowledge of this group in the last decade.Asociación Herpetológica Argentina (AHA

Experimental and theoretical investigation of generation of a cross-polarized wave by cascading of two different second-order processes

A nonlinear optical effect in which a linearly polarized wave propagating in a single quadratic medium is converted into a wave that is cross polarized to the input wave is investigated theoretically and observed experimentally in ␤-barium borate crystal. It is proved that this effect is a result of cascading of two different second-order processes. It starts with the generation of an extraordinary second-harmonic wave by type I interaction and is followed by type II difference-frequency mixing between the second-harmonic wave and the ordinary fundamental wave. The experiment was performed (a) for phase-matched type I interaction and non-phase-matched type II interaction and (b) for non-phase-matched type I interaction and phase-matched type II interaction. The observed generation of a cross-polarized wave is to our knowledge the only cubic effect whose first manifestation has been observed in quadratic crystal