918 research outputs found
Vinhos que pensam - parte ii|iii: utilização da condutividade elétrica aparente do solo na instalação e gestão das culturas: exemplificação na vinha
Vinhos que pensam - parte ii|iii: utilização da condutividade elétrica aparente do solo na instalação e gestão das culturas: exemplificação na vinh
Vinhos que pensam - parte i|iii: gestão do vigor vegetativo da vinha a partir de sensores ativos multiespectrais próximos
Vinhos que pensam - parte i|iii: gestão do vigor vegetativo da vinha a partir de sensores ativos multiespectrais próximo
Finite-gap equations for strings on AdS_3 x S^3 x T^4 with mixed 3-form flux
We study superstrings on AdS_3 x S^3 x T^4 supported by a combination of
Ramond-Ramond and Neveu-Schwarz-Neveu-Schwarz three form fluxes, and construct
a set of finite-gap equations that describe the classical string spectrum.
Using the recently proposed all-loop S-matrix we write down the all-loop Bethe
ansatz equations for the massive sector. In the thermodynamic limit the Bethe
ansatz reproduces the finite-gap equations. As part of this derivation we
propose expressions for the leading order dressing phases. These phases differ
from the well-known Arutyunov-Frolov-Staudacher phase that appears in the pure
Ramond-Ramond case. We also consider the one-loop quantization of the algebraic
curve and determine the one-loop corrections to the dressing phases. Finally we
consider some classical string solutions including finite size giant magnons
and circular strings.Comment: 44 pages, 3 figures. v2: references and a discussion about
perturbative results adde
Anthropogenic disturbance in tropical forests can double biodiversity loss from deforestation
Concerted political attention has focused on reducing deforestation1,2,3, and this remains the cornerstone of most biodiversity conservation strategies4,5,6. However, maintaining forest cover may not reduce anthropogenic forest disturbances, which are rarely considered in conservation programmes6. These disturbances occur both within forests, including selective logging and wildfires7,8, and at the landscape level, through edge, area and isolation effects9. Until now, the combined effect of anthropogenic disturbance on the conservation value of remnant primary forests has remained unknown, making it impossible to assess the relative importance of forest disturbance and forest loss. Here we address these knowledge gaps using a large data set of plants, birds and dung beetles (1,538, 460 and 156 species, respectively) sampled in 36 catchments in the Brazilian state of Pará. Catchments retaining more than 69–80% forest cover lost more conservation value from disturbance than from forest loss. For example, a 20% loss of primary forest, the maximum level of deforestation allowed on Amazonian properties under Brazil’s Forest Code5, resulted in a 39–54% loss of conservation value: 96–171% more than expected without considering disturbance effects. We extrapolated the disturbance-mediated loss of conservation value throughout Pará, which covers 25% of the Brazilian Amazon. Although disturbed forests retained considerable conservation value compared with deforested areas, the toll of disturbance outside Pará’s strictly protected areas is equivalent to the loss of 92,000–139,000 km2 of primary forest. Even this lowest estimate is greater than the area deforested across the entire Brazilian Amazon between 2006 and 2015 (ref. 10). Species distribution models showed that both landscape and within-forest disturbances contributed to biodiversity loss, with the greatest negative effects on species of high conservation and functional value. These results demonstrate an urgent need for policy interventions that go beyond the maintenance of forest cover to safeguard the hyper-diversity of tropical forest ecosystems
The all-loop integrable spin-chain for strings on AdS3 × S 3 × T 4: The massive sector
We bootstrap the all-loop dynamic S-matrix for the homogeneous psu (1, 1|2)2 spin-chain believed to correspond to the discretization of the massive modes of string theory on AdS3 × S 3 × T 4. The S-matrix is the tensor product of two copies of the su (1|1)2 invariant S-matrix constructed recently for the d (2, 1; α)2 chain, and depends on two anti-symmetric dressing phases. We write down the crossing equations that these phases have to satisfy. Furthermore, we present the corresponding Bethe Ansatz, which differs from the one previously conjectured, and discuss how our construction matches several recent perturbative calculations
Laparoscopic treatment of intestinal malrotation in neonates and infants: retrospective study
Intestinal malrotation in neonates or infants may require urgent surgical treatment, especially when volvulus and vascular compromise of the midgut are suspected. Successful laparoscopic management of malrotation has been described in a number of case reports. It remains unclear, however, whether laparoscopy for the treatment of malrotation has a success rate equal to that of open surgery and what relative risks exist in terms of conversion and redo surgery in larger numbers of patients. This report describes a retrospective analysis of the clinical outcome for 45 children who underwent laparoscopic treatment of intestinal malrotation at the authors' institution. The 45 patients in this series, ages several days to 13 years, underwent a diagnostic laparoscopy for suspected intestinal malrotation. For 37 patients, malrotation with or without volvulus was diagnosed. All these patients underwent laparoscopic derotation and Ladd's procedure. Successful laparoscopic treatment of intestinal malrotation could be performed in 75% of the cases (n = 28), and conversion to an open procedure was necessary in 25% of the cases (n = 9). The median hospital stay was 11 days (range, 2-60 days). Postoperative clinical relapse due to recurrence of malrotation, volvulus, or both occurred for 19% of the laparoscopically treated patients (n = 7). These patients underwent laparoscopic (n = 1) or open (n = 6) redo surgery. Diagnostic laparoscopy is the procedure of choice when intestinal malrotation is suspected. If present, malrotation can be treated adequately with laparoscopic surgery in the majority of cases. Nevertheless, to prevent recurrence of malrotation or volvulus, a low threshold for conversion to an open procedure is mandated
An empirical investigation of the influence of collaboration in Finance on article impact
We investigate the impact of collaborative research in academic Finance literature to find out whether and to what extent collaboration leads to higher impact articles (6,667 articles across 2001-2007 extracted from the Web of Science). Using the top 5 % as ranked by the 4-year citation counts following publication, we also follow related secondary research questions such as the relationships between article impact and author impact; collaboration and average author impact of an article; and, the nature of geographic collaboration. Key findings indicate: collaboration does lead to articles of higher impact but there is no significant marginal value for collaboration beyond three authors; high impact articles are not monopolized by high impact authors; collaboration and the average author impact of high-impact articles are positively associated, where collaborative articles have a higher mean author impact in comparison to single-author articles; and collaboration among the authors of high impact articles is mostly cross-institutional
Trade-offs between vegetative growth and acorn production in Quercus lobata during a mast year: the relevance of crop size and hierarchical level within the canopy
The concept of trade-offs between reproduction and other fitness traits is a fundamental principle of life history theory. For many plant species, the cost of sexual reproduction affects vegetative growth in years of high seed production through the allocation of resources to reproduction at different hierarchical levels of canopy organization. We have examined these tradeoffs at the shoot and branch level in an endemic California oak, Quercus lobata, during a mast year. To determine whether acorn production caused a reduction in vegetative growth, we studied trees that were high and low acorn producers, respectively. We observed that in both low and high acorn producers, shoots without acorns located adjacent to reproductive shoots showed reduced vegetative growth but that reduced branch-level growth on acorn-bearing branches occurred only in low acorn producers. The availability of local resources, measured as previous year growth, was the main factor determining acorn biomass. These findings show that the costs of reproduction varied among hierarchical levels, suggesting some degree of physiological autonomy of shoots in terms of acorn production. Costs also differed among trees with different acorn crops, suggesting that trees with large acorn crops had more available resources to allocate for growth and acorn production and to compensate for immediate local costs of seed production. These findings provide new insight into the proximate mechanisms for mast-seeding as a reproductive strategy
Osteochondral transplantation using autografts from the upper tibio-fibular joint for the treatment of knee cartilage lesions
Purpose Treatment of large cartilage lesions of the knee
in weight-bearing areas is still a controversy and challenging topic. Autologous osteochondral mosaicplasty has
proven to be a valid option for treatment but donor site
morbidity with most frequently used autografts remains a
source of concern. This study aims to assess clinical results
and safety profile of autologous osteochondral graft from
the upper tibio-fibular joint applied to reconstruct symptomatic osteochondral lesions of the knee.
Methods Thirty-one patients (22 men and 9 women) with
grade 4 cartilage lesions in the knee were operated by
mosaicplasty technique using autologous osteochondral
graft from the upper tibio-fibular joint, between 1998 and
2006. Clinical assessment included visual analog scale
(VAS) for pain and Lysholm score. All patients were
evaluated by MRI pre- and post-operatively regarding joint
congruency as good, fair (inferior to 1 mm incongruence),
and poor (incongruence higher than 1 mm registered in any
frame). Donor zone status was evaluated according to
specific protocol considering upper tibio-fibular joint
instability, pain, neurological complications, lateral collateral ligament insufficiency, or ankle complaints.
Results Mean age at surgery was 30.1 years (SD 12.2). In
respect to lesion sites, 22 were located in weight-bearing
area of medial femoral condyle, 7 in lateral femoral condyle, 1 in trochlea, and 1 in patella. Mean follow-up was
110.1 months (SD 23.2). Mean area of lesion was 3.3 cm
2
(SD 1.7), and a variable number of cylinders were used,
mean 2.5 (SD 1.3). Mean VAS score improved from 47.1
(SD 10.1) to 20.0 (SD 11.5); p = 0.00. Similarly, mean
Lysholm score increased from 45.7 (SD 4.5) to 85.3
(SD 7.0); p = 0.00. The level of patient satisfaction was
evaluated, and 28 patients declared to be satisfied/very
satisfied and would do surgery again, while 3 declared as
unsatisfied with the procedure and would not submit to
surgery again. These three patients had lower clinical scores
and kept complaints related to the original problem but
unrelated to donor zone. MRI score significantly improved
at 18–24 months comparing with pre-operative (p = 0.004).
No radiographic or clinical complications related to donor
zone with implication in activity were registered.
Conclusions This work corroborates that mosaicplasty
technique using autologous osteochondral graft from the
upper tibio-fibular joint is effective to treat osteochondral
defects in the knee joint. No relevant complications related
to donor zone were registered
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