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MYRSIDEA POVEDAI
THE COMMUNICATION ........
On Mon, Sep 5, 2011 at 2:22 AM, Miroslav Capek <capek@ivb.cz> wrote:
Dear Jorge,
How are you? We have just come back from Peru where we stayed for six
weeks and did research into ectoparasites in birds.
I am writing on behalf of the whole team to give you some good news about
the results of our research. When we were leaving Costa Rica last year you
said you would be interested to hear about our publications concerning our
research in Volcan Barva. We are pleased to send you our first paper, which
has just been published in the Journal of Parasitology. It describes a
species of chewing louse which is new to science.
Its
specific name is “povedai” as we decided to name it after you in
recognition of your friendship, hospitality and considerable help during our
stay at your place. Other scientific publications are under preparation.
I am sending best regards from Oldrich Sychra, Filip Kounek, Ivan Literak
as well as Martina Literakova.
Best wishes
Mirek
--
Ing. Miroslav CAPEK, CSc.
Department of Avian Ecology
Institute of Vertebrate Biology
AS CR, v. v. i.
Kvetna 8
6 0 3
6 5 Brno
C Z E C H R E P U B L I C
THE PUBLICATION
..........
MYRSIDEA POVEDAI
(PHTHIRAPTERA: MENOPONIDAE), A NEW SPECIES OF CHEWING LOUSE FROM PHAINOPTILA
MELANOXANTHA (PASSERIFORMES: BOMBYCILLIDAE)
Oldrich Sychra, Filip
Kounek, Miroslav Capek*, and Ivan Literak Department of Biology and Wildlife
Diseases, Faculty of Veterinary Hygiene and Ecology, University of Veterinary
and Pharmaceutical Sciences, Palackeho 1-3, 612 42 Brno, Czech Republic. e-mail:
sychrao@vfu.cz
ABSTRACT: A description and illustrations are given for Myrsidea povedai n. sp.
from the black-and-yellow silky-flycatcher Phainoptila melanoxantha. The
female of M. povedai is distinguished from those of other species of Myrsidea
from Costa Rican passerine hosts by a unique combination of the following
characteristics: (1) well-developed hypopharynx, (2) well-defined median gap
in the rows of tergal setae and another gap between groups of setae on
lateral side of tergites II–VII and the most central seta, and (3) enlarged
metanotum with at least 23 setae.
These characters place M.
povedai close to Myrsidea campestrisfrom Euneornis campestris andMyrsidea
marinifrom Pezopetes capitalis(both from the Emberizidae). The female of M.
povedai can be easily separeted from both aforementioned species by the
abdomen without conspicuously enlarged tergites. Moreover, the male of M.
povedai is characterized by a unique male genital sclerite, which is quite
long (0.13–0.15), tapered apically, with a long median line, and without
subapical processes. This is the first record of a chewing louse from this host
and the first record of Myrsidea from the passerine family Bombycillidae. All
7 birds examined in Costa Rica in 2010 were parasitized with M. povedai. Mean
abundance was 11.6, with intensity range 4–27 lice per bird.
The black-and-yellow
silky-flycatcher (Phainoptila melanoxantha) represents a monotypic genus,
which is endemic to Costa Rica and western Panama. It is an enigmatic avian
lineage because its relationships to other passerines have long been controversial.
It is usually placed into the Ptilogonatidae (del Hoyo et
al., 2005). However, the most recent taxonomic survey recommends placing all
ptilogonatids as a subfamily into the Bombycillidae
(Spellman et al., 2008). Myrsidea Waterston is the
most speciose menoponid genus parasitizing mainly passerines.
It currently contains 328 recognized species
throughout the world, with 309 of them recorded
from 343 host species in 46 families of Passeriformes (Price et
al., 2003; Palma and Price, 2010). Despite its abundance,
no species of Myrsidea has been described from passerine
bombycillids (sensu Spellman et al., 2008). Here we describe a
new species of chewing louse Myrsidea, which represents
the first from the Bombycillidae and from the black-and-yellow
silky-flycatcher.
MATERIALS AND METHODS
We conducted fieldwork
during the 2010 rainy season at 2 study sites in Costa
Rica: (1) Sacramento, Tamarak Lodge (10u069N, 84u079W, elevation
2,430 m; 176 birds of 29 species were examined from 30 July 2010 to 3
August 2010) and (2) Parque Nacional Braulio Carrillo, Sector
Volcan Barva (10u079N, 84u079W, elevation 2,619 m; 117 birds of 20
species were examined from 4 to 8 August 2010). At these sites, dawn-to-dusk
mist netting was conducted to capture as many bird species
and individuals as possible and to collect their ectoparasites.
A line of
about 100 m of mist nets was checked at least once an hour. Every
individual bird was identified, sexed, and aged using Stiles and Skutch
(1989) and Garrigues and Dean (2007). Lice were collected using the
fumigation chamber method (Clayton and Drown, 2001). Lice were
stored in 70% ethanol and subsequently cleared and then slide mounted in
Canada balsam as permanent slides for proper identification, following the
technique of Palma (1978). All measurements are in millimeters.
DESCRIPTION
Myrsidea povedai n. sp. (Figs.
1–4)
Diagnosis female (n 5 6):
Head: Hypopharyngeal sclerites strongly developed,
reaching gular plate. Length of head seta 10, 0.06–0.08; seta 11, 0.12–0.13;
ratio10/11, 0.50–0.62. Gula with 5–7 setae on each side, posterior-most
much heavier and longer than others. Thorax: Pronotum with 6
setae on posterior marginal and 3 short spiniform setae at each lateral
corner; well-developed elongate prosternal plate rounded anteriorly.
Metanotum enlarged, with 23–27 setae on conspicuously rounded
posterior margin.
Metapleurites with 4 short spiniform strong setae; metasternal
plate large, triangular, with 4–5 setae on each side. Legs: The first
tibia with 3 outer lateral ventral and 4 dorsal setae; femur III with 17– 21 setae
in ventral brush. Abdomen: Without conspicuously enlarged tergites,
tergites I and II medially compressed by enlarged metanotum with convex
posterior margin medially, with well-defined median gap in the rows of
tergal setae (Fig. 1). Well-defined gap also between groups of setaeon
lateral side of tergites II–VII and the most central seta. Tergal setae: I, 20–27; II,
20–24; III, 20–26; IV, 18–24; V, 19–25; VI, 17–24; VII, 15–18; VIII, 8
(only 1 female with 10). Setae on tergites I and II quite long, extending
over next 3 tergites. Postspiracular setae extremely long on II and IV
(0.53–0.55), very long on VIII (0.40–0.45), long on I and VII (0.35– 0.36) and
much shorter on III and V–VI (0.18–0.23). Without medioanterior
tergal, sternal, or pleural setae. Sternite I small, without setae.
Sternal setae: II, 4 in each aster, 18–22 marginal between asters, 7–9 medioanterior;
III, 28–38; IV, 35–43; V, 40–50; VI, 35–38; VII, 15–20; VIII–IX,
13–16 marginal, 8–10 anterior setae. Posterior margin of subgenital
plate serrated. Anus with 33–46 setae in each ventral and dorsal
fringe. Length of inner posterior seta of last tergum 0.04–0.05; short lateral
marginal seta of last segment 0.05–0.07. Dimensions:Temple width, 0.50–0.52;
head length, 0.30–0.31; prothorax width, 0.31–0.32; metathorax width,
0.50–0.52; abdomen width at level of segment IV, 0.62–0.70; anus width,
0.23–0.24; total length, 1.51–1.55. Male (n 5 6): Head: Length
of head seta 10, 0.06–0.07; seta 11, 0.10– 0.12;
ratio10/11, 0.50–0.70. Gula with 5–6 setae on each side. Thorax: Metanotum
with 11–14 setae on posterior margin, metasternal plate with 3–4 setae
on each side. Legs: Femur III with 15–20 setae in ventral brush. Abdomen:
Tergites with well-defined median gap in the rows of tergal setae.
Tergal setae: I, 14–17; II, 17–20; III, 17–21; IV, 17–21; V, 17–21; VI, 16–19;
VII, 13–16; VIII, 12. Postspiracular setae very long on II, IV, and VIII (0.42–0.48),
long on I and VII (0.25–0.30), and much shorter on III and V–VI
(0.12–0.20). Sternal setae: II, 4 in each aster, 13–16 marginal between
asters, 6–10 medioanterior; III, 20–29; IV, 28–36; V, 33–37; VI, 31–36;
VII, 15–22; VIII–IX, 9–12, remainder of plate, 7–13. Sternite VII separate
from subgenital plate of fused VIII–IX; with 8 internal anal setae. Length of
inner posterior seta of last tergum 0.06–0.07; short lateral marginal
seta of last segment 0.02. Genitalia: As in Figure 2. Genital sac sclerite
as in Figure 3, quite long, tapered apically, with quite long median line,
without subapical processes. Dimensions: Temple width, 0.44–0.47; head
length, 0.28–0.29; prothorax width, 0.28–0.30; metathorax width,
Received 6 December 2010;
revised 3 February 2011; accepted 11 February 2011.
* Institute of Vertebrate
Biology, Academy of Sciences of the Czech Republic,
v. v. i., Kvetna 8, 603 65 Brno, Czech Republic.
DOI: 10.1645/GE-2715.1 J.
Parasitol., 97(4), 2011, pp. 593–595 F American Society of
Parasitologists 2011 5930.37–0.40; abdomen width
at level of segment IV, 0.45–0.48; genitalia length,
0.42–0.45; genitalia width, 0.12; genital sac sclerite length, 0.13– 0.15;
total length, 1.30–1.36.
Taxonomic summary:
Type host: Phainoptila
melanoxantha Salvin.
Type material: Female
holotype ex P. melanoxantha (slide O. Sychra CR96),
Costa Rica, Sacramento, Tamarak Lodge (10u069N, 84u079W, elevation
2,430 m), 3 August 2010, Sychra, Kounek, Capek and Literak leg. Paratypes:
1 female and 2 males with same data as holotype, 4 females and 4
males ex P. melanoxantha, Costa Rica, Parque Nacional Braulio Carrillo,
Sector Volcan Barva (10u079N, 84u079W, elevation 2,619 m), 7–8 August
2010, Sychra, Kounek, Capek and Literak
leg. Deposited in the National
Biodiversity Institute (INBio), Santo Domingo de Heredia, Costa Rica
(O. Sychra CR96–97); Moravian Museum, Brno (MZM),
Czech Republic (O. Sychra
CR98–99); and Natural History Museum,
London, United Kingdom (O.
Sychra CR100–101).
Range of infestatation and
abundance:Intensity range 5 4–27 and mean abundance
5 11.6.
Etymology:
This species is named in honor of Jorge Poveda Quiro´s (Costa Rica) in recognition of his friendship and invaluable help during our research field stay on Volca´n Barva, Costa Rica, in 2010.
Remarks
The female of M. povedai is
distinguished from those of other species of Myrsidea
from Costa Rican passerine hosts by a unique combination of the following
characteristics: (1) well-developed hypopharynx, (2) well-defined median gap
in the rows of tergal setae and another gap between groups of setae on
lateral side of tergites II–VII and the most central seta, and (3) enlarged
metanotum with at least 23 setae. These characters place M. povedai
FIGURES 1–4. Myrsidea povedai n. sp. (1) Female. (2) Male. (3) Male genitalia. (4)
Male genital sclerite.
Scales: 0.50 mm (Figs. 1–2),
0.10 mm
(Figs. 3–4). For Figures 1–2 dorsal side on left, ventral side on right.
594 THE JOURNAL OF
PARASITOLOGY, VOL. 97, NO. 4, AUGUST 2011 close to
M. campestris from Euneornis campestris and M. marini from Pezopetes
capitalis (both from the Emberizidae). The female of M. povedai can be
easily separeted from both aforementioned species by the abdomen without
conspicuously enlarged tergites. Moreover, male of M. povedai is characterized
by unique male genital sclerite, which is quite long (0.13–0.15), tapered
apically, with long median line, and without subapical processes.
This is the first record of
a chewing louse from P. melanoxantha and the first
record of Myrsidea from the Bombycillidae. All 7 birds examined were
parasitized with 81 specimens of M. povedai (40 males, 21 females, and 20
nymphs were found). Although an even sex ratio is predominant in most
ectoparasites, in some species of chewing lice, a skewed ratio can be observed
(Price et al., 2003). Clayton et al. (1992) found that ischnoceran lice had
more female-biased sex ratios, whereas amblyceran lice had more male-biased
ratios. This corroborates our results (male:female ratio 5 1:0.53).
The skewed age ratio observed (adult:nymph 5 1:0.33) is also similar to
those indicated by Clayton et al. (1992) and suggests the existence
of stable chewing lice populations (Mashall, 1981). Eggs of lice were found
on 4 of 7 black-and-yellow silky-flycatchers examined. They were
located on the head and neck of host.
DISCUSSION
Although there has been no
comprehensive study of the entire genus due to the large
number of species involved, all evidence suggests
that each host species or group of closely related host
species is parasitized by 1,
or more, closely related species of Myrsidea (Clay, 1966; Price
and Dalgleish, 2007). Therefore, the only practical way to deal
with the taxonomy of such a large genus is to treat lice from
each host family as a unit. While most species of
Myrsidea are more easily identified by examining females,
males may show characteristics needed for phylogenetic analysis
(Clay, 1966). Species of Myrsidea grouped together based on
characteristics of the male genital sclerite are frequently found to be
parasitic on a group of related hosts, usually from 1 bird family.
The male of Myrsidea povedai is characterized by a unique male
genital sclerite. If other members of the Ptilogonatinae and Bombycillidae
harbor Myrsidea with the same type of male genital
sclerite, this may lend support to findings of molecular phylogenetic
analysis and confirm validity as to the recently
described taxonomic status
of the Bombycillidae sensu Spellman et al. (2008). The only way
to clarify this case will be to collect and study
moreMyrsidea occurring on other species of Bombycillidae.
ACKNOWLEDGMENTS
The fieldwork part of the
study was permitted by the Ministerio de Ambiente,
Energia y Telecomunicaciones de Costa Rica (Resolucion No
136-2010-SINAC). We are grateful to Bernardo Calvo Rodriguez and Martina
Literakova for their help in the field. Funding was provided by the Grant
Agency of the Academy of Sciences of the Czech Republic (Grant
IAA601690901). M.C. was also supported in part by the Ministry of
Education, Youth, and Sports of the Czech Republic (Grant LC06073).
LITERATURE CITED
CLAY, T. 1966. Contributions
towards a revision of Myrsidea Waterston. I.
(Menoponidae: Mallophaga). Bulletin of the British Museum (Natural
History), Entomology 17: 327–395.
CLAYTON, D. H., AND D. M.
DROWN. 2001. Critical evaluation of five methods
for quantifying chewing lice (Insecta: Phthiraptera). Journal of Parasitology
87: 1291–300.
———, R. D. GREGORY, AND R.
D. PRICE. 1992. Comparative ecology of neotropical
bird lice (Insecta, Phthiraptera). Journal of Animal Ecology
61: 781–795.
DEL HOYO, J., A. ELLIOT, AND
D. CHRISTIE (EDS.). 2005. Handbook of the birds
of the world, Vol. 10. Cuckoo-shrikes to thrushes. Lynx Edicions,
Barcelona, Spain, 895 p.
GARRIGUES, R., AND R. DEAN.
2007. The birds of Costa Rica: A field guide.
Christopher Helm, London, U.K., 387 p.
MARSHALL, A. G. 1981. The
ecology of ectoparasitic insects. Academic Press,
London, U.K., 459 p.
PALMA R. L. 1978. Slide
mounting of lice: A description of the Canada balsam
technique. New Zealand Entomologist 6: 432–436.
———, AND R. D. PRICE. 2010.
The species of Myrsidea Waterston (Insecta: Phthiraptera: Menoponidae)
from the Galapagos Islands, with descriptions of new
taxa. Tuhinga 21: 135–146.
PRICE, R. D., AND R. C.
DALGLEISH. 2007. Myrsidea Waterston (Phthiraptera: Menoponidae)
from the Emberizidae (Passeriformes), with
descriptions of 13 new species. Zootaxa 1467: 1–18.
———, R. A. HELLENTHAL, R. L.
PALMA, K. P. JOHNSON, AND D. H. CLAYTON. 2003. The chewing
lice: World checklist and biological overview. Illinois Natural
History Survey Special Publication 24, Champaign,
Illinois, 501 p.
SPELLMAN, G. M., A. CIBOIS,
R. G. MOYLE, K. WINKER, AND F. K. BARKER. 2008. Clarifying the
systematics of an enigmatic avian lineage: What is a
bombycillid? Molecular Phylogenetics and Evolution
49: 1036–1040.
STILES, F. G., AND A.
SKUTCH. 1989. A guide to the birds of Costa Rica. Christopher
Helm, London, U.K., 511 p.
THE NEW ECTOPARASITE FOUND....
FIGURES 1–4. Myrsidea povedai n. sp. (1) Female. (2) Male. (3) Male genitalia. (4) Male genital sclerite.
Scales: 0.50 mm (Figs. 1–2), 0.10 mm
|
jueves, 4 de abril de 2013
Un triunfo costarricense
a. Un Editorial del periodico La Nacion, Costa Rica
El Tratado sobre el Comercio de Armas no alcanzará a satisfacer los nobles ideales que lo inspiran, pero es un paso en la dirección correcta
La distinguida participación costarricense en la fragua del histórico tratado reafirma las convicciones de su pueblo y los altos propósitos de su política exterior
En la práctica, el Tratado sobre el Comercio de Armas, aprobado el martes por la Asamblea General de la ONU, no alcanzará a satisfacer los nobles ideales que lo inspiran. Es, sin embargo, un paso en la dirección correcta. Una holgada mayoría de 154 países respaldó el texto propuesto por Costa Rica, pero tres grandes naciones le negaron su apoyo mediante la abstención y un peligroso trío de países belicistas votó en contra.
La oposición de Corea del Norte, Irán y Siria es fácil de explicar. Los tres exhiben una conducta de abierto desafío a la comunidad internacional. Corea emitió su voto negativo a pocos días de revivir el espectro de la guerra con su vecina del sur e Irán lo hizo en medio del rechazo a la supervisión internacional de su desarrollo nuclear. El embajador de Siria representa en la Asamblea General un régimen ensangrentado, cuyo empleo de las armas más crueles y prohibidas indigna a las naciones civilizadas.
Las abstenciones de India, Rusia y China, tres potencias nucleares integrantes del selecto club de países influyentes, tampoco encierra misterios.
Los dos últimos figuran entre los principales exportadores de armas, y el envío de material bélico, incluso a regímenes cuestionables, es un elemento relevante de su política exterior. La India, por su parte, es el principal importador de armas convencionales.
Estados Unidos, el mayor exportador de armas del planeta, con un tercio del mercado global, votó el Tratado luego de descarrilar una negociación en julio. La exclusión de los aviones teledirigidos (drones), intensamente empleados en la guerra contra el terrorismo, es obra de la diplomacia norteamericana. El voto estadounidense en Nueva York no vaticina una conducta similar en Washington si el Ejecutivo alguna vez envía el texto a ratificación por el Senado.
Menos claras son las razones de la abstención de otros 20 países, en particular los de la Alianza Bolivariana para los Pueblos de Nuestra América (ALBA). Bolivia, Cuba, Ecuador, Nicaragua y Venezuela negaron el voto favorable porque el Tratado “privilegia” los países exportadores, dándoles la posibilidad de calificar a sus clientes según criterios “subjetivos” y puede ser “manipulado políticamente”. En consecuencia, el texto “no es equilibrado” y tampoco incluye una prohibición expresa de transferir armas a grupos armados no estatales.
Pero las abstenciones, el peso de los países que las ejercieron, los votos en contra, el belicismo de sus emisores y las dificultades del proceso de ratificación, no impiden celebrar la existencia, por primera vez en la historia de la humanidad, de un tratado regulador de la venta de armas convencionales, estimada en $60.000 millones al año. Es la más explícita manifestación de un ideal y un primer paso trascendental en la lucha por hacerlo realidad.
El pacto no rige al interior de las naciones, pero obliga a las partes a controlar la transferencia de armas convencionales como tanques, vehículos de combate, artillería de alto calibre, aviones, helicópteros y buques de guerra, misiles y lanzacohetes, armas cortas y ligeras. Quienes lo ratifiquen no podrán transferir esas armas en violación de embargos o cuando puedan ser utilizadas para el genocidio y ataques a civiles. La exportación queda prohibida si las armas pueden ser usadas para violar los derechos humanos o existe el riesgo de que caigan en manos de terroristas o el crimen organizado. Los exportadores que ratifiquen el acuerdo, deben adoptar medidas para prevenir el desvío de armamento al mercado ilegal y sopesar si la transferencia mina la paz y la seguridad.
Costa Rica, proponente e impulsora del acuerdo, tiene doble motivo para festejar. Su distinguida participación en la fragua del histórico tratado reafirma las convicciones de su pueblo y los altos propósitos de su política exterior. El mérito es del expresidente Óscar Arias, la Fundación Arias para la Paz, la diplomacia costarricense de los últimos siete años y el embajador Eduardo Ulibarri, representante ante las Naciones Unidas en el momento culminante de la votación. Juntos han hecho historia.
Fuente: La Nacion, Costa Rica, Editorial
...........................................................................................................................................
b. Un articulo en Bitnavegantes
Posted: 03 Apr 2013 10:00 AM PDT
Desde los distintos Estados siempre han estado haciendo campaña para hacer ver a los ciudadanos que son unos irresponsables y que no deben tener armas.
Pero la realidad es tozuda y demuestra que las armas no son peligrosas cuando las tienen los ciudadanos para defenderse.
En realidad el verdadero peligro de las armas proviene de cuando están en poder de los Estados para traficar con ellas y fomentar guerras. Es tan vil esta ideología que, vestida de patriotismo, los Estados pretenden convencer a la gente de que si matas a otras personas en una guerra en la que ellos se han metido eso ya no es asesinato.
Por eso me alegra este comunicado de Amnistía Internacional:
«Hoy, los gobiernos representados en las Naciones Unidas (ONU) han aprobado prácticamente por unanimidad un Tratado sobre el Comercio de Armas que prohibirá a los Estados transferir armas convencionales a otros países si saben que van a ser utilizadas para cometer genocidio, crímenes de lesa humanidad o crímenes de guerra o facilitar su comisión."
»El tratado obliga, además, a todos los gobiernos a evaluar el riesgo de transferir armas, municiones o componentes a otros países donde puedan ser utilizados para cometer o facilitar graves violaciones del derecho internacional humanitario y de los derechos humanos. Los Estados han acordado que, si ese riesgo fundamental es real y no puede mitigarse, la transferencia no se lleve a cabo.
»“Si se piensa en el poder político y los amplios intereses económicos que están en juego para los grandes productores y exportadores de armas, este tratado constituye un homenaje tanto a la sociedad civil que defendió la idea de salvar vidas y reducir el sufrimiento humano como a los gobiernos que hicieron caso a ese llamamiento”, ha señalado Widney Brown, directora general de Derecho Internacional y Política de Amnistía internacional.
»A pesar de todas las dificultades, Amnistía Internacional junto con muchas organizaciones de todo el mundo decidimos cargarnos de paciencia y trabajar intensamente durante años en conseguir este cambio. Era necesario salvar a hombres, mujeres, niños y niñas. Era necesario actuar y reducir el sufrimiento humano.
»El tratado adoptado afecta a las principales categorías de armas convencionales, incluidas las armas pequeñas y las armas ligeras, que proliferan en países con conflictos de baja intensidad, violencia armada y cantidades ingentes de víctimas civiles.
»Dicho tratado estará abierto a la firma y ratificación a partir del 3 de junio de 2013 en la Asamblea General de la ONU y entrará en vigor al poco tiempo de haber sido ratificado por 50 Estados.»
- Más información en Amnistía Internacional.
- Imagen: Delegados/as de Amnistía Internacional en la Conferencia de la ONU sobre el Tratado de Comercio de Armas. Crédito AI.
En realidad el verdadero peligro de las armas proviene de cuando están en poder de los Estados para traficar con ellas y fomentar guerras. Es tan vil esta ideología que, vestida de patriotismo, los Estados pretenden convencer a la gente de que si matas a otras personas en una guerra en la que ellos se han metido eso ya no es asesinato.
Por eso me alegra este comunicado de Amnistía Internacional:
«Hoy, los gobiernos representados en las Naciones Unidas (ONU) han aprobado prácticamente por unanimidad un Tratado sobre el Comercio de Armas que prohibirá a los Estados transferir armas convencionales a otros países si saben que van a ser utilizadas para cometer genocidio, crímenes de lesa humanidad o crímenes de guerra o facilitar su comisión."
»El tratado obliga, además, a todos los gobiernos a evaluar el riesgo de transferir armas, municiones o componentes a otros países donde puedan ser utilizados para cometer o facilitar graves violaciones del derecho internacional humanitario y de los derechos humanos. Los Estados han acordado que, si ese riesgo fundamental es real y no puede mitigarse, la transferencia no se lleve a cabo.
»“Si se piensa en el poder político y los amplios intereses económicos que están en juego para los grandes productores y exportadores de armas, este tratado constituye un homenaje tanto a la sociedad civil que defendió la idea de salvar vidas y reducir el sufrimiento humano como a los gobiernos que hicieron caso a ese llamamiento”, ha señalado Widney Brown, directora general de Derecho Internacional y Política de Amnistía internacional.
»A pesar de todas las dificultades, Amnistía Internacional junto con muchas organizaciones de todo el mundo decidimos cargarnos de paciencia y trabajar intensamente durante años en conseguir este cambio. Era necesario salvar a hombres, mujeres, niños y niñas. Era necesario actuar y reducir el sufrimiento humano.
»El tratado adoptado afecta a las principales categorías de armas convencionales, incluidas las armas pequeñas y las armas ligeras, que proliferan en países con conflictos de baja intensidad, violencia armada y cantidades ingentes de víctimas civiles.
»Dicho tratado estará abierto a la firma y ratificación a partir del 3 de junio de 2013 en la Asamblea General de la ONU y entrará en vigor al poco tiempo de haber sido ratificado por 50 Estados.»
- Más información en Amnistía Internacional.
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Fuente: Pedro Donaire, Bitnavegantes
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miércoles, 3 de abril de 2013
QUESTION : to Lawrence M. Krauss
What happened before the big bang?
ANSWER:
¨This is a frustrating question because first, it presumes that just because we know there was a big bang, we understand it back to t=0 or 'before'.
This is like presuming evolutionary biology can explain the origin of life itself, which it cannot, since we need to know chemistry and the conditions of the early earth to address it.
Similarly, we simply don't have a physical theory that works back to t=0 so we cannot answer the question.
But more than that, all of our current ideas suggest, alas, that it isn't a good question!
Saying that always frustrates the listener, but science often tells us that naive questions aren't good questions because they make presumptions that are unwarranted.
Because space and time are coupled to matter and energy in general relativity, it is eminently plausible that if space spontaneously popped into existence, so did time.
Namely, time and space are both classical concepts that may have a limited domain of validity, and so the question what was 'before the big bang" may simply be a bad question because there was no 'before'! Time didn't exist.
That answer of course makes no one happy, but it may be true. As I often say, the business of the universe is not to make you happy….¨
Source : Lawrence M. Krauss
Physicist/Cosmologist, ASU; Author of : ¨A Universe from Nothing¨
martes, 2 de abril de 2013
Planck sees a cosmic journey 13 billion years in the making
02 Apr 2013
Cosmologists using data from ESA's Planck satellite have compiled the first all-sky image of the distribution of dark matter across the entire history of the Universe as seen projected on the sky. This is made possible by analysing the tiny distortions imprinted on the photons of the Cosmic Microwave Background (CMB) by the gravitational lensing effect of massive cosmic structures. As photons travelled through these structures, which consist primarily of dark matter, their paths became bent, slightly changing the pattern of the CMB. Although noisy, this image is the first measurement performed over almost the whole sky of the gravitational potential that distorts the CMB, and is one of the highlights of Planck's cosmological results. With these unique data, cosmologists can investigate 13 billion years of the formation of structure in the Universe. The data agree very well with the expectations from the leading cosmological model that describes the origin and evolution of cosmic structure in the Universe. |
All-sky map of dark matter distribution in the Universe. Credit: ESA and the Planck Collaboration.
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While scanning the sky to study the most ancient light emitted in the Universe – the Cosmic Microwave Background (CMB) – ESA's Planck satellite is also probing the entire history of how structure formed and evolved in the cosmos.
Because the photons that make up the CMB were emitted only 380,000 years after the Big Bang, they have travelled for over 13 billion years across the Universe, witnessing the dramatic changes that took place during the various cosmic epochs such as the formation of stars, galaxies and galaxy clusters.
Several observable effects arise from the interaction between CMB photons and the large-scale structure they crossed during their journey. One of the most intriguing is gravitational lensing, the deflection of light as it travels in the vicinity of massive objects such as galaxies and galaxy clusters. Similar to what happens when light rays pass through a glass lens, the trajectories of photons are bent as they encounter these 'gravitational' lenses: as a result, the image that an observer sees when looking at a cosmic object, such as a galaxy, through a gravitational lens is distorted. In the most spectacular cases, the same galaxy can be imaged more than once, or its shape can be twisted and appear as a giant arc.
"In the case of the CMB, gravitational lensing due to cosmic large-scale structure creates tiny, additional distortions to the mottled pattern of the CMB temperature fluctuations. The effect is extremely small, but we have been able to isolate it exploiting Planck's combination of high sensitivity and angular resolution over the entire sky," comments Jan Tauber, Planck Project Scientist at ESA.
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Gravitational lensing of the Cosmic Microwave Background. (See also the animated version of this image.) Credit: ESA and the Planck Collaboration
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"The CMB consists of the most ancient photons emitted in the Universe's history: we can think of them as the ultimate 'cosmic storytellers'. The tale these photons are telling us begins with the epoch when they originated, 380,000 years after the Big Bang, when the cosmos consisted of an almost smooth fluid of particles: but that is only the start," explains Tauber. "Thanks to the detection of gravitational lensing experienced by CMB photons, we can use Planck to explore the subsequent epochs in the history of the Universe, during which the invisible dark matter built up the 'cosmic web' and stars and galaxies started to form in the densest nodes of this intricate network of structure."
On their way to the Solar System, where they are eventually detected by the sensors on board Planck, photons from the CMB may cross many different massive systems as well as empty spaces. The photons encounter structures in different evolutionary stages, since the massive structures grow denser and the cosmic voids become less dense as time goes by. All of the structures from the different cosmic epochs contribute to bending the path of CMB photons. The total effect of these multiple deflections is a modification to the pattern of CMB temperature fluctuations, thus changing the typical 'shapes' of hot and cold spots in the CMB. These changes only affect the CMB on very small scales – of the order of a few arc minutes – where the primordial CMB does not exhibit significant structure, making the separation of the signal due to gravitational lensing from the primordial CMB signal a very complex procedure.
"Isolating the gravitational lensing effect in the CMB is extremely difficult since we are looking for the deformation of a signal that has very little structure itself," explains Karim Benabed of the Institut d’Astrophysique de Paris, France. "We use statistical methods to exploit the minute changes in the shape of the CMB pattern and reconstruct the gravitational potential of the structure that caused these distortions," he adds.
The result is an image of the three-dimensional large-scale distribution of dark matter across the cosmos as seen projected on the two-dimensional plane of the sky. The reconstruction technique used to compile this image relies on deviations of the shapes of hot and cold spots in the CMB from their 'typical' shape, and it is impossible to avoid the introduction of statistical 'noise' in the reconstruction, since only some deformations detected in the data are due to gravitational lensing. On average however, the reconstruction is quite accurate.
"Extracting information about the large-scale distribution of dark matter from the CMB is similar to trying to identify what lies on the ground beneath a thick layer of snow. Part of the structure we see in the white surface is caused by actual corrugations of the ground or by stones and other objects that are coated by snow," says Benabed. "However, we might also see other features that are simply due to an uneven distribution within the snow layer and mistakenly deduce that they correspond to some real structure underneath."
"The image we have reconstructed is nevertheless good enough to have considerable statistical power, as we can measure the amplitude of the power spectrum of the dark matter distribution with a precision of four per cent," comments Duncan Hanson of McGill University, Canada.
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Planck's gravitational lensing power spectrum. Credit: ESA and the Planck Collaboration.
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The task of disentangling the contributions imprinted on the CMB by massive objects and voids at different distances – which correspond to different epochs in cosmic history – is very complex. Cosmologists rely on the fact that gravitational lenses, just like ordinary lenses, are most efficient when located midway between the source of light and the observer. For this reason, the structures that contribute most to gravitationally lens the CMB are those located at redshift z~2, corresponding to the epoch when the Universe was about three billion years old; taking into account cosmic expansion, this redshift identifies structures that are 'half-way' between the present epoch and the time when the CMB was released. However, more massive gravitational lenses are stronger, and these are more abundant in the later epochs of cosmic history so another substantial contribution to the gravitational lensing of the CMB comes from structures at redshifts between z~2 and z~1, corresponding to the epoch when the Universe was between three and six billion years old.
"The projected dark matter distribution inferred from the Planck data agrees very well with our expectations," explains Hanson. "In the leading cosmological scenario, the seeds of cosmic structure have been embedded during cosmic inflation – a very early epoch of accelerated expansion that took place immediately after the Big Bang – and later grew denser and more massive under the effect of gravity. Eventually, this gave rise to a highly structured network consisting mainly of dark matter, and galaxies formed in the densest knots of this web. The large-scale distribution of structure in such a Universe would lens the CMB just as we see it with Planck," he adds.
The study of the gravitationally-lensed CMB provides cosmologists with a wealth of information about the 13-billion-year history of cosmic structure formation. This complements the view of the Universe that can be extracted from the analysis of the primordial CMB signal. By investigating the minute fluctuations in the primordial CMB, cosmologists can constrain several properties of the Universe, such as the density of dark matter, the speed of cosmic expansion and the relative amount of primordial fluctuations – the seeds of nascent cosmic structures – on different scales. However, the primordial CMB is a relic of the early Universe and does not contain direct information about the further evolution of structure in the cosmos. Since gravitational lensing arises later in cosmic history, it provides cosmologists with an extra set of information about the late Universe. This will enable them to estimate additional parameters, such as the properties of dark energy – the repulsive force driving the currently accelerated cosmic expansion, against which structures keep building up – or the mass of neutrinos, the particles that play an important role in damping the formation of cosmic structure on small scales.
"The detection of gravitational lensing of the CMB over nearly the whole sky is an extraordinary milestone achieved by Planck: astronomers and cosmologists will scrutinise this unique data set for years to come," says Tauber. "In particular, by combining the study of the gravitationally-lensed CMB with other probes of the large-scale structure such as galaxy surveys, we will be able to investigate the complex relation between the distribution of dark and luminous matter in our Universe."
NOTES FOR EDITORS
This article is based on results described in the Planck Collaboration paper: "Planck 2013 results. XVII. Gravitational lensing by large-scale structure", submitted to Astronomy & Astrophysics.
The new data from Planck are based on the first 15.5 months of its all-sky surveys. Launched in 2009, Planck was designed to map the sky in nine frequencies using two state-of-the-art instruments: the Low Frequency Instrument (LFI), which includes the frequency bands 30–70 GHz, and the High Frequency Instrument (HFI), which includes the frequency bands 100–857 GHz. HFI completed its survey in January 2012, while LFI continues to operate.
Planck's first all-sky image was released in 2010 and the first scientific data were released in 2011. Since then, scientists have been extracting the foreground emissions that lie between us and the Universe's first light to reveal the Cosmic Microwave Background. The first cosmology results from Planck were presented at a press conference on 21 March 2013; further details will be presented at the 47th ESLAB Symposium, 2-5 April 2013. The next set of cosmology data will be released in early 2014.
The Planck Scientific Collaboration consists of all the scientists who have contributed to the development of the Planck mission, and who participate in the scientific exploitation of the Planck data during the proprietary period. These scientists are members of one or more of four consortia: the LFI Consortium, the HFI Consortium, the DK-Planck Consortium, and ESA's Planck Science Office. The two European-led Planck Data Processing Centres are located in Paris, France and Trieste, Italy.
The LFI consortium is led by N. Mandolesi, Agenzia Spaziale Italiana, Italy (deputy PI: M. Bersanelli, Università degli Studi di Milano, Italy), and was responsible for the development and operation of the LFI instrument. The HFI consortium is lead by J.L. Puget, Institut d’Astrophysique Spatiale in Orsay, France (deputy PI: F. Bouchet, Institut d'Astrophysique de Paris, France), and was responsible for the development and operation of the HFI instrument. The Institut d’Astrophysique Spatiale in Orsay is a Unité Mixte de Recherche (UMR8617) of the CNRS (Centre National de la Recherche Scientifique) and the Université Paris-Sud 11. The Institut d’Astrophysique de Paris is a Unité Mixte de Recherche (UMR 7095) of the CNRS and the Université Pierre et Marie Curie of Paris.
The development of the Planck mission was supported by substantial financial and technological contributions of ESA Member States. More than 40 per cent of the mission's development cost was provided by the agencies supplying HFI and LFI. France and Italy, through the two leading funding agencies CNES and ASI, and the national research bodies, provided more than half of the national funding. The contribution of ESA Member States is even more significant for the scientific operation of the mission and the processing of its data. ESA Member States also provided key technologies such as the innovative cooler that enabled the mission’s instrumentation to be maintained at just one-tenth of a degree above absolute zero (–273.15°C). Important technologies and payload elements were also contributed by NASA.
Background information to the topics discussed in this release – the Cosmic Microwave Background and the history of structure formation in the Universe – is available in the Planck Toolkit (http://sci.esa.int/jump.cfm?oid=51552).
The 47th ESLAB Symposium, “The Universe as seen by Planck” is an international conference dedicated to an in-depth look at the results from the Planck mission, and will be held from 2 to 5 April 2013 at ESA/ESTEC in Noordwijk, The Netherlands. More information at: http://www.congrexprojects.com/13a11
CONTACTS
Karim Benabed
Institut d’Astrophysique de Paris, France
Email: benabed
iap.fr
Institut d’Astrophysique de Paris, France
Email: benabed
iap.fr
Duncan Hanson
McGill University
Montréal, QC, Canada
Email: dhansonphysics.mcgill.ca
McGill University
Montréal, QC, Canada
Email: dhanson
physics.mcgill.ca
Jan Tauber
ESA Planck Project Scientist
Research and Scientific Support Department
Directorate of Science and Robotic Exploration
ESA, The Netherlands
Email: jan.tauberesa.int
Phone: +31-71-565-5342
ESA Planck Project Scientist
Research and Scientific Support Department
Directorate of Science and Robotic Exploration
ESA, The Netherlands
Email: jan.tauber
esa.intPhone: +31-71-565-5342
Last Update: 02 Apr 2013
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