An assessment of the use of the Jackass penguin as a sampler of the marine environment

Bibliography: leaves 68-83.In this thesis the use of the jackass penguin Spheniscus demersus as a sampler of the marine environment is assessed. Between February 1987 and July 1988, 638 monthly diet samples were obtained from adult jackass penguins at west - (Marcus and Jutten Islands) and southwest-coast (Dyer Island) colonies off South Africa, supplementing data collected since 1980. Penguin diet was compared over time and between colonies in order to establish the presence or absence of qualitative changes or quantified trends in the biology of pelagic schooling fish species important to the South African purseseine fishery, viz. anchovy Engraulis capensis, pilchard Sardinops ocellatus, maasbanker Trachurus trachurus and red-eye Etrumeus whiteheadii. The principal prey of jackass penguins and major contributor to commercial catches is anchovy and, consequently, the biology of this fish species was emphasized. Monthly and annual trends in prey composition and anchovy size-range were related to the availability, abundance and distribution of the penguins' prey species in the marine environment

PHYCOBILISOMES AND ISOLATED PHYCOBILIPROTEINS. EFFECT OF GLUTARDIALDEHYDE AND BENZOQUINONE ON FLUORESCENCE

The fluorescence of the biliproteins C-phycocyanin from Spirulina platensis, B-phycoerythrin from Porphyridium cruentum and of isolated whole P. cruentum phycobilisomes is quenched in the presence of glutardialdehyde (GA) or benzoquinone (BQ). The kinetics of fluorescence decrease thus induced is biphasic. If GA is used as a quencher, the fluorescence can be recovered at 77 K. Contrary to the GA-effect, only a minor recovery takes place with BQ at 77K, thus demonstrating a different mechanism of action of GA and BQ on biliprotein

THEORETICAL STUDIES OF BILIPROTEIN CHROMOPHORES AND RELATED BILE PIGMENTS BY MOLECULAR ORBITAL AND RAMACHANDRAN TYPE CALCULATIONS

Ramachandran calculations have been used to gain insight into steric hindrance in bile pigments related to biliprotein chromophores. The high optical activity of denatured phycocyanin, as compared to phycoerythrin, has been related to the asymmetric substitution at ring A, which shifts the equilibrium towards the P-helical form of the chromophore. Geometric effects on the electronic structures and transitions have then been studied by molecular orbital calculations for several conjugation systems including the chromophores of phycocyanin. phytochrome P,, cations, cation radicals and tautomeric forms. For these different chromophores some general trends can be deduced. For instance, for a given change in the gross shape (e.g. either unfolding of the molecule from a cyclic-helical to a fully extended geometry, or upon out-of-plane twists of the pyrrole ring A) of the molecules under study, the predicted absorption spectra all change in a simikar way. Nonetheless, there are characteristic distinctions between the different n-systems, both in the transition energies and the charge distribution, which can be related to their known differences in spectroscopic properties and their reactivity

What makes cities more productive? Agglomeration economies and the role of urban governance: evidence from 5 OECD countries

This paper estimates agglomeration benefits across five OECD countries, and represents the first empirical analysis that combines evidence on agglomeration benefits and the productivity impact of metropolitan governance structures, while taking into account the potential sorting of individuals across cities. The comparability of results in a multi-country setting is supported through the use of a new internationally-harmonised definition of cities based on economic linkages rather than administrative boundaries. In line with the literature, the analysis confirms that city productivity increases with city size but finds that cities with fragmented governance structures tend to have lower levels of productivity. This effect is mitigated by the existence of a metropolitan governance body

The Accretion Rates and Spectral Energy Distributions of BL Lacertae Objects

We investigate the relationship between accretion rates and the spectral energy distributions (SEDs) of BL Lac objects, using a sample of objects for which published information on the host galaxies, emission-line luminosities, and peak frequencies and luminosities of their SEDs are available. The sample is composed of 43 BL Lac objects which have a relatively continuous distribution of peak frequencies. Under the assumption that the observed emission lines are photoionized by the central accretion disk, we use the line luminosities to estimate the accretion luminosities and hence accretion rates. We find that low frequency-peaked BL Lac objects (LBLs) span a wide range of accretion rates, whereas high frequency-peaked BL Lac objects (HBLs) cover a more restricted range of lower values. There appears to be a continuous distribution of accretion rates between the two subclasses of BL Lac objects. We find that the peak frequency of the SED, \pknu, correlates with the accretion rate, approximately with the form \pknu\propto \Lambda^{-3} in HBLs and \pknu \propto \Lambda^{-0.25} in LBLs, where $\Lambda \equiv L_{\rm lines}/c^2$. The peak luminosity of the SED is also correlated with $\Lambda$. These results suggest that the accretion rate influences the shape of the SED in BL Lac objects. They also support models which couple the jet and the accretion disk. We present a physical scenario to account for the empirical trends.Comment: 6 pages in emulateapj.sty, 3 figures 1 table. The Astrophysical Journal (in press

A review of image processing methods for fetal head and brain analysis in ultrasound images

Background and objective: Examination of head shape and brain during the fetal period is paramount to evaluate head growth, predict neurodevelopment, and to diagnose fetal abnormalities. Prenatal ultrasound is the most used imaging modality to perform this evaluation. However, manual interpretation of these images is challenging and thus, image processing methods to aid this task have been proposed in the literature. This article aims to present a review of these state-of-the-art methods. Methods: In this work, it is intended to analyze and categorize the different image processing methods to evaluate fetal head and brain in ultrasound imaging. For that, a total of 109 articles published since 2010 were analyzed. Different applications are covered in this review, namely analysis of head shape and inner structures of the brain, standard clinical planes identification, fetal development analysis, and methods for image processing enhancement. Results: For each application, the reviewed techniques are categorized according to their theoretical approach, and the more suitable image processing methods to accurately analyze the head and brain are identified. Furthermore, future research needs are discussed. Finally, topics whose research is lacking in the literature are outlined, along with new fields of applications. Conclusions: A multitude of image processing methods has been proposed for fetal head and brain analysis. Summarily, techniques from different categories showed their potential to improve clinical practice. Nevertheless, further research must be conducted to potentiate the current methods, especially for 3D imaging analysis and acquisition and for abnormality detection. (c) 2022 Elsevier B.V. All rights reserved.FCT - Fundação para a Ciência e a Tecnologia(UIDB/00319/2020)This work was funded by projects “NORTE-01–0145-FEDER- 0 0 0 059 , NORTE-01-0145-FEDER-024300 and “NORTE-01–0145- FEDER-0 0 0 045 , supported by Northern Portugal Regional Opera- tional Programme (Norte2020), under the Portugal 2020 Partner- ship Agreement, through the European Regional Development Fund (FEDER). It was also funded by national funds, through the FCT – Fundação para a Ciência e Tecnologia within the R&D Units Project Scope: UIDB/00319/2020 and by FCT and FCT/MCTES in the scope of the projects UIDB/05549/2020 and UIDP/05549/2020 . The authors also acknowledge support from FCT and the Euro- pean Social Found, through Programa Operacional Capital Humano (POCH), in the scope of the PhD grant SFRH/BD/136670/2018 and SFRH/BD/136721/2018

Momentum transport from current-driven reconnection in astrophysical disks

Current-driven reconnection is investigated as a possible mechanism for angular momentum transport in astrophysical disks. A theoretical and computational study of angular momentum transport from current-driven magnetohydrodynamic instabilities is performed. It is found that both a single resistive tearing instability and an ideal instability can transport momentum in the presence of azimuthal Keplerian flow. The structure of the Maxwell stress is examined for a single mode through analytic quasilinear theory and computation. Full nonlinear multiple mode computation shows that a global Maxwell stress causes significant momentum transport.Comment: 14 figures; Accepted for publication in Ap

The molecular species responsible for α1-antitrypsin deficiency are suppressed by a small molecule chaperone

The formation of ordered Z (Glu342Lys) α1-antitrypsin polymers in hepatocytes is central to liver disease in α1-antitrypsin deficiency. In vitro experiments have identified an intermediate conformational state (M*) that precedes polymer formation, but this has yet to be identified in vivo. Moreover, the mechanism of polymer formation and their fate in cells have been incompletely characterised. We have used cell models of disease in conjunction with conformation-selective monoclonal antibodies and a small molecule inhibitor of polymerisation to define the dynamics of polymer formation, accumulation and secretion. Pulse-chase experiments demonstrate that Z α1-antitrypsin accumulates as short-chain polymers that partition with soluble cellular components and are partially secreted by cells. These precede the formation of larger, insoluble polymers with a longer half-life (10.9 ± 1.7 h and 20.9 ± 7.4 h for soluble and insoluble polymers, respectively). The M* intermediate (or a by-product thereof) was identified in the cells by a conformation-specific monoclonal antibody. This was completely abrogated by treatment with the small molecule, which also blocked the formation of intracellular polymers. These data allow us to conclude that the M* conformation is central to polymerisation of Z α1-antitrypsin in vivo; preventing its accumulation represents a tractable approach for pharmacological treatment of this condition; polymers are partially secreted; and polymers exist as two distinct populations in cells whose different dynamics have likely consequences for the aetiology of the disease

3D facial landmark localization for cephalometric analysis

Cephalometric analysis is an important and routine task in the medical field to assess craniofacial development and to diagnose cranial deformities and midline facial abnormalities. The advance of 3D digital techniques potentiated the development of 3D cephalometry, which includes the localization of cephalometric landmarks in the 3D models. However, manual labeling is still applied, being a tedious and time-consuming task, highly prone to intra/inter-observer variability. In this paper, a framework to automatically locate cephalometric landmarks in 3D facial models is presented. The landmark detector is divided into two stages: (i) creation of 2D maps representative of the 3D model; and (ii) landmarks' detection through a regression convolutional neural network (CNN). In the first step, the 3D facial model is transformed to 2D maps retrieved from 3D shape descriptors. In the second stage, a CNN is used to estimate a probability map for each landmark using the 2D representations as input. The detection method was evaluated in three different datasets of 3D facial models, namely the Texas 3DFR, the BU3DFE, and the Bosphorus databases. An average distance error of 2.3, 3.0, and 3.2 mm were obtained for the landmarks evaluated on each dataset. The obtained results demonstrated the accuracy of the method in different 3D facial datasets with a performance competitive to the state-of-the-art methods, allowing to prove its versability to different 3D models. Clinical Relevance - Overall, the performance of the landmark detector demonstrated its potential to be used for 3D cephalometric analysis.FCT - Fundação para a Ciência e a Tecnologia(LASI-LA/P/0104/2020