109 research outputs found

    ANALISIS DEL CRECIMIENTO DE Ananas Comosus (L.) MERR. POR EL METODO DE β-SPLINES

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    Se realizó un experimento de análisis en crecimiento de piña (Ananas comosus {L.) Merr.) cv. 'Española Roja', sembrada en una finca de los aledaños de Jusepín, Edo. Monagas. Se cosecharon mensualmente, al azar, 1 O muestras de la fitomasa de la comunidad y se separaron el follaje asimilatorio y no asimilatorio, los tallos, las raíces, los retoños axilares, el tejido precursor de la inflorescencia, los hijos basales, la corona y los hijos de la corona, el pedúnculo y el fruto. Se secaron las muestras en una estufa a 85"C hasta peso constante. Se midió el área foliar y se procesaron las características de crecimiento de las plantas de piña a partir de los datos primarios de peso seco y área foliar de las muestras, mediante las técnicas de análisis funcional de crecimiento de Hunt. El peso seco total de la planta de piña a los 600días después de la siembra (DDS) fue de 3.940 g m-2, de los cuales 53 % correspondieron a follaje asimilatorio y 2 % a follaje nó asimilatorio. El resto (45%) estuvo representado por el peso seco de tallos, de raíces, de hijos y de otras estructuras. El peso promedio de los frutos frescos (sin corona ni hijos) fue 1.050 g con un rendimiento promedio de 35,03 tm ha-1 de frutos. El índice de área foliar asimilatoria (IAF) máximo fue de 8,14 m2m-2 (96 %) y el de no asimilatorio 0,30 m2m-2 (4 %) a los 600 DDS. Para esa misma fecha las mayores tasasabsolutas (C) y relativa de crecimiento del peso seco total (1RCW) fueron de 33,8 g m -2 d -1 y de o, 02 g g- ld-1 respectivamente. La tasa neta de asimilación (INA) mostró valores amplios de varianza durante el ciclo general del cultivo y la variación del cociente de superficie foliar (CAF) no fue significativamente diferente.   PALABRAS CLAVES: Anna, CAM, crecimiento.   ABSTRACT   In a field of Spanish red pineapple, ten random samples of phytomass were collected at monthly intervals. The material was separated as to assimilatory and non - assimilatory foliage, stems, roots, axillary shoots, precursor inflorescence tissue, basal shoots, crown and crown shoots, peduncle, and fruil The samples were oven ed at 8511C to constant weighl Leaf area was measured and the growth characteristics of the plants were determined using the primary data on dry matter and leaf area of the samples, using Hunt's technique of functional growth analysis. The total dry matter of a pineapple plant, 600 days post-planting (DDS) was 3.940 gm-2, of which assimilatory foliage constituted 53%, non-assimilatory foliage 2%, while stems, roots, sprouts and other structures represented 45%. The mean fresh weightof pineapple fruits (without crown) was 1.050 g and the mean yield of fruits was 35,03 tm ha-1.Ihe maximan assimilatory leaf area index (LAI) was 8,14 m 2m-2 ( 96% ); non-assimilatory being 0,30 m2 m-2 (4%) at600DDS. Atthe samedate, thehighestabsolute (C) and relative cates of  wth of total dry mass (TRCW) were 33,8 gm- d-1 and 0,02 gg- 1d-1 respectively. The net rate of assimilation (INA) showed wide variance values during the general growing cycle; the variation of foliage surface coefficient (CAF) was not significant.   KEY WORDS: Ananas, CAM, growth

    Patterns of ascending aortic dilatation and predictors of surgical replacement of the aorta: A comparison of bicuspid and tricuspid aortic valve patients over eight years of follow-up

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    Background: Predictors of thoracic aorta growth and early cardiac surgery in patients with bicuspid aortic valve are undefined. Our aim was to identify predictors of ascending aorta dilatation and cardiac surgery in patients with bicuspid aortic valve (BAV). Methods: Forty-one patients with BAV were compared with 165 patients with tricuspid aortic valve (TAV). All patients had LV EF > 50%, normal LV dimensions, and similar degree of aortic root or ascending aorta dilatation at enrollment. Patients with more than mild aortic stenosis or regurgitation were excluded. A CT-scan was available on 76% of the population, and an echocardiogram was repeated every year for a median time of 4 years (range: 2 to 8 years). Patterns of aortic expansion in BAV and TAV groups were analyzed by a mixed-effects longitudinal linear model. In the time-to-event analysis, the primary end point was elective or emergent surgery for aorta replacement. Results: BAV patients were younger, while the TAV group had greater LV wall thickness, arterial hypertension, and dyslipidemia than BAV patients. Growth rate was 0.46 ± 0.04 mm/year, similar in BAV and TAV groups (p = 0.70). Predictors of cardiac surgery were aorta dimensions at baseline (HR 1.23, p = 0.01), severe aortic regurgitation developed during follow-up (HR 3.49, p 0.04), family history of aortic aneurysm (HR 4.16, p 1.73), and history of STEMI (HR 3.64, p < 0.001). Conclusions: Classic baseline risk factors were more commonly observed in TAV aortopathy compared with BAV aortopathy. However, it is reassuring that, though diagnosed with aneurysm on average 10 years earlier and in the absence of arterial hypertension, BAV patients had a relatively low growth rate, similar to patients with a tricuspid valve. Irrespective of aortic valve morphology, patients with a family history of aortic aneurysm, history of coronary artery disease, and those who developed severe aortic regurgitation at follow-up, had the highest chances of being referred for surgery

    How Group Size Affects Vigilance Dynamics and Time Allocation Patterns: The Key Role of Imitation and Tempo

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    In the context of social foraging, predator detection has been the subject of numerous studies, which acknowledge the adaptive response of the individual to the trade-off between feeding and vigilance. Typically, animals gain energy by increasing their feeding time and decreasing their vigilance effort with increasing group size, without increasing their risk of predation (‘group size effect’). Research on the biological utility of vigilance has prevailed over considerations of the mechanistic rules that link individual decisions to group behavior. With sheep as a model species, we identified how the behaviors of conspecifics affect the individual decisions to switch activity. We highlight a simple mechanism whereby the group size effect on collective vigilance dynamics is shaped by two key features: the magnitude of social amplification and intrinsic differences between foraging and scanning bout durations. Our results highlight a positive correlation between the duration of scanning and foraging bouts at the level of the group. This finding reveals the existence of groups with high and low rates of transition between activies, suggesting individual variations in the transition rate, or ‘tempo’. We present a mathematical model based on behavioral rules derived from experiments. Our theoretical predictions show that the system is robust in respect to variations in the propensity to imitate scanning and foraging, yet flexible in respect to differences in the duration of activity bouts. The model shows how individual decisions contribute to collective behavior patterns and how the group, in turn, facilitates individual-level adaptive responses

    Long-Term Implications of Atrial Fibrillation in Patients With Degenerative Mitral Regurgitation

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    Background: Scientific guidelines consider atrial fibrillation (AF) complicating degenerative mitral regurgitation (DMR) a debated indication for surgery. Objectives: This study analyzed the prognostic/therapeutic implications of AF at DMR diagnosis and long-term. Methods: Patients were enrolled in the MIDA (Mitral Regurgitation International Database) registry, which reported the consecutive, multicenter, international experience with DMR due to flail leaflets echocardiographically diagnosed. Results: Among 2,425 patients (age 67 \ub1 13 years; 71% male, 67% asymptomatic, ejection fraction 64 \ub1 10%), 1,646 presented at diagnosis with sinus rhythm (SR), 317 with paroxysmal AD, and 462 with persistent AF. Underlying clinical/instrumental characteristics progressively worsened from SR to paroxysmal to persistent AF. During follow-up, paroxysmal and persistent AF were associated with excess mortality (10-year survival in SR and in paroxysmal and persistent AF was 74 \ub1 1%, 59 \ub1 3%, and 46 \ub1 2%, respectively; p < 0.0001), that persisted 20 years post-diagnosis and independently of all baseline characteristics (p values <0.0001). Surgery (n = 1,889, repair 88%) was associated with better survival versus medical management, regardless of all baseline characteristics and rhythm (adjusted hazard ratio: 0.26; 95% confidence interval: 0.23 to 0.30; p < 0.0001) but post-surgical outcome remained affected by AF (10-year post-surgical survival in SR and in paroxysmal and persistent AF was 82 \ub1 1%, 70 \ub1 4%, and 57 \ub1 3%, respectively; p < 0.0001). Conclusions: AF is a frequent occurrence at DMR diagnosis. Although AF is associated with older age and more severe presentation of DMR, it is independently associated with excess mortality long-term after diagnosis. Surgery is followed by improved survival in each cardiac rhythm subset, but persistence of excess risk is observed for each type of AF. Our study indicates that detection of AF, even paroxysmal, should trigger prompt consideration for surgery

    OSIRIS – The scientific camera system onboard Rosetta

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    The Optical, Spectroscopic, and Infrared Remote Imaging System OSIRIS is the scientific camera system onboard the Rosetta spacecraft (Figure 1). The advanced high performance imaging system will be pivotal for the success of the Rosetta mission. OSIRIS will detect 67P/Churyumov-Gerasimenko from a distance of more than 106 km, characterise the comet shape and volume, its rotational state and find a suitable landing spot for Philae, the Rosetta lander. OSIRIS will observe the nucleus, its activity and surroundings down to a scale of ~2 cm px−1. The observations will begin well before the onset of cometary activity and will extend over months until the comet reaches perihelion. During the rendezvous episode of the Rosetta mission, OSIRIS will provide key information about the nature of cometary nuclei and reveal the physics of cometary activity that leads to the gas and dust coma. OSIRIS comprises a high resolution Narrow Angle Camera (NAC) unit and a Wide Angle Camera (WAC) unit accompanied by three electronics boxes. The NAC is designed to obtain high resolution images of the surface of comet 7P/Churyumov-Gerasimenko through 12 discrete filters over the wavelength range 250–1000 nm at an angular resolution of 18.6 μrad px−1. The WAC is optimised to provide images of the near-nucleus environment in 14 discrete filters at an angular resolution of 101 μrad px−1. The two units use identical shutter, filter wheel, front door, and detector systems. They are operated by a common Data Processing Unit. The OSIRIS instrument has a total mass of 35 kg and is provided by institutes from six European countrie

    Enhancing the sensitivity of magnetic sensors by 3D metamaterial shells

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    Magnetic sensors are key elements in our interconnected smart society. Their sensitivity becomes essential for many applications in fields such as biomedicine, computer memories, geophysics, or space exploration. Here we present a universal way of increasing the sensitivity of magnetic sensors by surrounding them with a spherical metamaterial shell with specially designed anisotropic magnetic properties. We analytically demonstrate that the magnetic field in the sensing area is enhanced by our metamaterial shell by a known factor that depends on the shell radii ratio. When the applied field is non-uniform, as for dipolar magnetic field sources, field gradient is increased as well. A proof-of-concept experimental realization confirms the theoretical predictions. The metamaterial shell is also shown to concentrate time-dependent magnetic fields upto frequencies of 100 kHz

    CHMP1A encodes an essential regulator of BMI1-INK4A in cerebellar development

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    Charged multivesicular body protein 1A (CHMP1A; also known as chromatin-modifying protein 1A) is a member of the ESCRT-III (endosomal sorting complex required for transport-III) complex but is also suggested to localize to the nuclear matrix and regulate chromatin structure. Here, we show that loss-of-function mutations in human CHMP1A cause reduced cerebellar size (pontocerebellar hypoplasia) and reduced cerebral cortical size (microcephaly). CHMP1A-mutant cells show impaired proliferation, with increased expression of INK4A, a negative regulator of stem cell proliferation. Chromatin immunoprecipitation suggests loss of the normal INK4A repression by BMI in these cells. Morpholino-based knockdown of zebrafish chmp1a resulted in brain defects resembling those seen after bmi1a and bmi1b knockdown, which were partially rescued by INK4A ortholog knockdown, further supporting links between CHMP1A and BMI1-mediated regulation of INK4A. Our results suggest that CHMP1A serves as a critical link between cytoplasmic signals and BMI1-mediated chromatin modifications that regulate proliferation of central nervous system progenitor cells

    Conceptual robustness in simultaneous engineering: An extension of Taguchi's parameter design

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    Simultaneous engineering processes involve multifunctional teams; team members simultaneously make decisions about many parts of the product-production system and aspects of the product life cycle. This paper argues that such simultaneous distributed decisions should be based on communications about sets of possibilities rather than single solutions. By extending Taguchi's parameter design concepts, we develop a robust and distributed decision-making procedure based on such communications. The procedure shows how a member of a design team can make appropriate decisions based on incomplete information from the other members of the team. More specifically, it (1) treats variations among the designs considered by other members of the design team as conceptual noise; (2) shows how to incorporate such noises into decisions that are robust against these variations; (3) describes a method for using the same data to provide preference information back to the other team members; and (4) provides a procedure for determining whether to release the conceptually robust design or to wait for further decisions by others. The method is demonstrated by part of a distributed design process for a rotary CNC milling machine. While Taguchi's approach is used as a starting point because it is widely known, these results can be generalized to use other robust decision techniques.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45879/1/163_2005_Article_BF01608400.pd
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