10,874 research outputs found
Two new species of Ammothea (Pycnogonida, Ammotheidae) from Antarctic waters
Two new species of the genus Ammothea are
described from Elephant Island and the South Shetlands
Islands, Antarctica. The material was captured during the
Polarstern cruise XXIII/8 to the Antarctic Peninsula area.
The main features of Ammothea pseudospinosa n. sp. are a
proboscis distinctly trilobulated distally with a constriction
at 2/3 of its length and dimorphism between the propodi of
the anterior (first and second) and posterior (third and
fourth) legs, and a trunk: proboscis length ratio of about
1.5. The main features of Ammothea childi n. sp. are a
cylindrical proboscis, longer than trunk length, and adults
with functional chelifores. These species are compared
with their closest congeners from the Southern Ocean:
A. pseudospinosa n. sp. with Ammothea spinosa and
Ammothea allopodes;A. childi n. sp. withAmmothea gigantea,
Ammothea bicorniculata and Ammothea hesperidensis
Colossendeis species (Pycnogonida: Colossendeidae) collected during the Italica XIX cruise to Victoria Land (Antarctica), with remarks on some taxonomic characters of the ovigers
The pycnogonid fauna of the genus Colossendeis collected during the Italica XIX cruise to Victoria Land (Ross Sea, Antarctica) was studied. A total of 19 specimens of six species were collected: Colossendeis australis (6), C. wilsoni (3), C. scotti (2), C. robusta (3), C. lilliei (2) and C. megalonyx (3). In the present contribution the observed variability of all collected Colossendeis species is described and illustrated. The previously synonymised C. lilliei is considered a different species from C. robusta. The observations made in this study lead us to discuss a controversy about the total number of oviger segments in this genus. Despite the currently established 10-segmented status, a short basal element is here considered to be a possible 11th segment. A detailed SEM study of the last oviger segment is carried out in all collected species, showing some intraspecific and the interspecific variability in the structures examined (shape and number of rows of compound spines, morphology of terminal claw, etc.). Finally, we discuss the taxonomic value of these characters of the last strigilis segment for distinguishing the Colossendeis species, and their possible utility in establishing internal phylogenetic relationships in future contributions
New findings and a new species of the genus Ammothea (Pycnogonida, Ammotheidae), with an updated identification key to all Antarctic and sub-Antarctic species
Specimens of the pycnogonid genus Ammothea
collected during the Polarstern cruise XXIII/8 (23
November 2006–30 January 2007) were studied. Nine
species were recognized in this collection: Ammothea
bentartica, A. bicorniculata, A. carolinensis, A. clausi, A.
longispina, A. minor, A. spinosa, A. striata and A. tibialis.
Three of them (A. bentartica, A. bicorniculata and A. tibialis) are reported for the second time, enlarging their
known geographical and bathymetric range. In the present
contribution, the observed morphological variability of all
collected Ammothea species is described and discussed.
For the identification and description of the material, different museum specimens were consulted. Among them,
we have consulted part of the Discovery collection housed
at the Natural History Museum in London. That material
was initially identified by Isabella Gordon, a reputed author
in the field of pycnogonid taxonomy. A new species, based
on a museum specimen previously highly confused in the
literature, is proposed in the present contribution as Ammothea isabellae n. sp. The new taxon is compared with its
closest congeners, especially with A. longispina and A.
stylirostris. Finally, we propose an updated dichotomous
key to species covering all currently known Antarctic and
sub-Antarctic Ammothea specie
Nuevo modo de desarrollo postembrionario en el género Ammothea (Pycnogonida: Ammotheidae) procedente de aguas Antárticas
In this paper the postembryonic development of Ammothea glacialis (family ammotheidae) is described. The
studied material was collected during the Italica XIX cruise to Victoria land, ross sea, antarctica. The external morphology
of three larval instars is described and illustrated. The development of A. glacialis has the following characteristics: (1)
protonymphon hatch from the eggs; (2) the larvae have yolk reserves and relatively large size (0.7 mm in length); (3) the
larvae remain on the ovigerous legs of males during several moults; (4) the larvae have reduced larval II-III appendages and
the spinning apparatus is absent; (5) the development of walking legs is sequential. This development is compared with those
previously known, especially with Propallene longiceps and Nymphon grossipes.Nuevo modo de desarrollo postembrionario en el género AmmotheA
(Pycnogonida: Ammotheidae)
procedente de aguas Antárticas. – En este trabajo se describe el desarrollo postembrionario de Ammothea glacialis
(familia ammotheidae). El material estudiado fue recolectado durante el crucero Itálica XIX a Tierra Victoria, en el mar de
ross, antártida. se describe e ilustra la morfología externa de tres estadios larvarios. El desarrollo de A. glacialis se caracteriza
por: (1) la larva eclosiona como protonymphon; (2) la larva es de tamaño relativo grande (0.7 mm de longitud) y con
reservas de vitelo; (3) la larva permanece en los ovígeros del macho durante varias mudas; (4) la larva presenta los apéndices
larvarios II y III reducidos y el “spinning apparatus” está ausente; (5) el desarrollo de las patas es secuencial. Este desarrollo
es comparado con otros desarrollos postembrionarios previamente conocidos, especialmente con los de Propallene longiceps
and Nymphon grossipes
Effect of agro-climatic conditions on near infrared spectra of extra virgin olive oils
Authentication of extra virgin olive oil requires fast and cost-effective analytical procedures, such as near infrared spectroscopy. Multivariate analysis and chemometrics have been successfully applied in several papers to gather qualitative and quantitative information of extra virgin olive oils from near infrared spectra. Moreover, there are many examples in the literature analysing the effect of agro-climatic conditions on food content, in general, and in olive oil components, in particular. But the majority of these studies considered a factor, a non-numerical variable, containing this meteorological information. The present work uses all the agro-climatic data with the aim of highlighting the linear relationships between them and the near infrared spectra. The study begins with a graphical motivation, continues with a bivariate analysis and, finally, applies redundancy analysis to extend and confirm the previous conclusions.Peer Reviewe
Política cultural exterior alemana en España durante la República de Weimar
El enorme desarrollo que la ciencia alemana vivió durante el ultimo tercio del siglo XIX y primeras décadas del siglo XX encuentra en la eficiencia de su aparato organizativo una de sus principales causas. El sistema Althoff y la Notgemeinschaft der Deutschen Wissenschaft fueron los resultados más brillantes de una política científica orientada a colocar a Alemania al frente del desarrollo cientifíco europeo.The emergence of a scientific policy in Germany at the end of the 19th century and at the beginning of the 20th century is due to the fact that efficiency of the German scientific burocracy system. The Althoff’s System and the Notgemeinschaft der Deutschen Wissenschaft were the most significant outcomes of one policy which strove for placing Germany on the top of the European scientific development
Reinterpretar la cultura española: el Centro de Estudios Históricos
El Centro de Estudios Históricos fue fundado por la Junta para Ampliación de Estudios en 1910. El objetivo era crear un sistema científico moderno, pero además los investigadores del Centro aspiraban a reinterpretar la cultura española, esto es, poner las nuevas bases sobre las que erigir un cuerpo doctrinal que diese carta de naturaleza a una nueva forma de aprehender la historia y la cultura española y contribuyese a la creación de un nuevo nacionalismo
Genetic Evidence for p75NTR-Dependent Tetraploidy in Cortical Projection Neurons from Adult Mice
A subpopulation of chick retinal projection neurons becomes tetraploid during development, an event prevented by blocking antibodies against p75 neurotrophin receptor (p75(NTR)). We have used an optimized flow cytometric assay, based on the analysis of unfixed brain cell nuclei, to study whether p75(NTR)-dependent neuronal tetraploidization takes place in the cerebral cortex, giving rise to projection neurons as well. We show that 3% of neurons in both murine neocortex and chick telencephalic derivatives are tetraploid, and that in the mouse ~85% of these neurons express the immediate early genes Erg-1 and c-Fos, indicating that they are functionally active. Tetraploid cortical neurons (65-80%) express CTIP2, a transcription factor specific for subcortical projection neurons in the mouse neocortex. During the period in which these neurons are born, p75(NTR) is detected in differentiating neurons undergoing DNA replication. Accordingly, p75(NTR)-deficient mice contain a reduced proportion of both NeuN and CTIP2-positive neocortical tetraploid neurons, thus providing genetic evidence for the participation of p75(NTR) in the induction of neuronal tetraploidy in the mouse neocortex. In the striatum tetraploidy is mainly associated with long-range projection neurons as well since ~80% of tetraploid neurons in this structure express calbindin, a marker of neostriatal-matrix spiny neurons, known to establish long-range projections to the substantia nigra and globus pallidus. In contrast, only 20% of tetraploid cortical neurons express calbindin, which is mainly expressed in layers II-III, where CTIP2 is absent. We conclude that tetraploidy mainly affects long-range projection neurons, being facilitated by p75(NTR) in the neocortex.Peer Reviewe
An Analysis of Global Research Trends on Greenhouse Technology: Towards a Sustainable Agriculture
Greenhouse farming is an agricultural management system that has demonstrated its efficiency in intensifying food production. These systems constitute a feasible alternative for ensuring food supply, which is one of the greatest challenges faced by humankind in the twenty-first century. Technology has been able to meet the challenges related to greenhouse farming in both contributing to overcoming its limitations, correcting adverse impacts and ensuring system sustainability. The objective of this article is to analyse the global research trends in greenhouse technology over the last two decades, in order to identify the main driving agents, the most outstanding research lines and possible gaps in the literature. Different methodologies have been used for the analysis; both quantitative and qualitative. The principal results show that there are different relevant lines of research related to different aspects of greenhouse farming: the use of water for irrigation, the design of the optimum structure of the greenhouse, conserving the soil in the best growing conditions, energy consumption of the system as a whole, climate control within the facility and pest control. The research is characterized by the being composed largely of ad hoc studies, which hinders the international collaboration between researchers and institutions. The research approach has shifted from being focused on increasing production and cost savings to aspects related to resource conservation and sustainability
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