Human milk fat is specially tailored to supply the developing infant with adequate and balanced nutrients. The present study aimed to quantify the composition of fatty acids, tocopherols and carotenoids in human milk, with special emphasis on the lactational changes. Colostrum, transitional and mature milk samples were collected longitudinally from the same forty-two healthy, well-nourished Chinese mothers. Fatty acids were quantified by GC with carotenoids (carotenes and xanthophylls) and tocopherols (α-, γ-tocopherol) determined by HPLC. Total fatty acid (TFA) content increased from 15·09 g/l in colostrum to 32·57 g/l in mature milk with the percentages of DHA and arachidonic acid (ARA) decreased. The ratio of n-6:n-3 PUFA and ARA:DHA remained constant during lactation at about 11:1 and 1·3:1, respectively. Both α-tocopherol and γ-tocopherol decreased over lactation with the ratio of α-:γ-tocopherol declined significantly from 7·21:1 to 4·21:1 (P < 0·001). Carotenoids all dropped from colostrum to mature milk as the less polar carotenes dropped by 88·67 %, while xanthophylls only dropped by 35·92 %. Lutein was predominated in both transitional and mature milk carotenoids (51·64–52·49 %), while colostrum carotenoids were mainly composed of lycopene (32·83 %) and β-carotene (30·78 %). The concentrations of tocopherols and xanthophylls but not carotenes were positively associated with TFA content in milk. These results suggested that colostrum and mature milk contained divergent lipid profiles and selective transfer mechanisms related to polarity might be involved. The present outcomes provide new insights for future breast-feeding studies, which also add in scientific evidences for the design of both initial and follow-on infant formulas.

This article considers what the nineteenth century can tell us about the nature of great power management under conditions of ambiguity in relation to the holders of great power status. It charts the development of an institutionalised role for the great powers as managers of international society but with a specific focus on the mutual recognition, and conferral, of status. Such a focus highlights the changing, and sometimes competing, perceptions of not only which states should be thought of as great powers, but also therefore whether the power structure of international society remained multipolar or shifted towards bipolarity or even unipolarity. The article argues that a ‘golden age’ of great power management existed during a period in which perceptions of great power status were in fact more fluid than the standard literature accounts for. This means that predictions surrounding the imminent demise of the social institution of great power management under an increasingly ambiguous interstate order today may well be misplaced.

Numeral phrases in Standard Arabic are known for gender and number mismatches1 between the numeral and the enumerated noun. This article reduces these mismatches to two morphological deletion rules. The first deletes the feminine morpheme of the numeral when the enumerated noun is feminine, and the second deletes the plural morpheme of the enumerated noun when the numeral carries a plural morpheme. The first rule is further restricted to deleting only feminine morphemes that are underlyingly part of the numeral, and not inherited via agreement with a feminine enumerated noun via a syntactic agreement process. The analysis in this article is consistent with Sadiqi's (2006) claim that the feminine form in Arabic is the basic one from which the masculine was derived historically by reducing the feminine form. The deletion analysis here also finds support from Chomsky's approach of deriving the masculine from the feminine as theoretically less costly and more explanatorily adequate.

This paper provides evidence that medial adjunct PPs in English are possible. On the basis of corpus data, it is shown that sentence-medial adjunct PPs are not unacceptable and are attested. Our corpus data also reveal a sharp asymmetry between negative and non-negative adjunct PPs. The analysis of the corpus revealed the following pattern: Non-negative adjunct PPs such as at that time resist medial position and instead tend to be postverbal; negative adjunct PPs such as at no time appear medially rather than postverbally. In the second part of the paper, we broaden the empirical domain and include negative complement PPs in the discussion. It is shown that when it comes to the licensing of question tags, English negative complement PPs, which are postverbal, pattern differently from postverbal negative adjunct PPs. That is, sentences with a postverbal negative adjunct PP pattern with negative sentences in taking a positive question tag, while sentences containing a postverbal negative argument PP pattern with affirmative sentences in taking a negative tag. To account for the observed adjunct–argument asymmetry in the licensing of question tags, we propose that clauses are typed for polarity and we explore the hypothesis that a polarity head in the left periphery of the clause is crucially involved in the licensing of sentential negation.

X-ray photoemission spectroscopy using synchrotron radiation from 100 to 1486.6 eV was used to investigate polarity-dependent differences between the Zn-polar (0001) and the O-polar () faces of ultrahigh vacuum cleaved hydrothermally grown ZnO single crystals. The cleaved polar surfaces showed a characteristic polarity effect in that the intensity of emission from the lowest binding energy O 2p related valence band states was significantly stronger on the Zn-polar face, even when the cleaved surfaces were imperfect with irregular nonatomically flat features. A residual submonolayer hydroxyl termination of approximately 0.5 ML was observed on both the Zn-polar and O-polar surfaces immediately after cleaving. The near-surface downward band bending on the O-polar face was removed by the cleaving process leaving almost flat bands, while on the cleaved Zn-polar face, emission from states above the valence band edge was observed.

The purpose of the present study was to determine whether the plasma membrance of the human oocyte is reorganised following fertlisation and during early cleavage. In order to characterise and localise the major sugar moieties on surface glycoporteins, oocytes and embroys were labelled with a range of flourescent lectins. Regional organisation of plasma membrane microvilli in oocytes and embryos was also studied using scanning electron microscopy (SEM). The plasma membrance of human oocytes, zygotes and early blastomeres stained strongly and homogeneously with concanavalin A and Triticum vulgaris lectin (WGA), indicationg the presence of plasma membrance glycoconjugates with α-D-mannosyl residues, sialic acid and β-NAc-glucosaminyl groups. We did not observe regional domains in oocytes and zygotes, suggesting that the plasma membrane is not topographically reorganised following fertilisation. SEM shows the surface of the human zygote to be organised into short microvilli 0.2–3.0 μm in length and at a density of 5–20/μm2. In early cleavage stages the microvilli are shorter and less frequent (0.2–1.0 μm; 1–5/μm2); however, there is no evidence of polarisation at this level of organisation, at either stage of development. The surface of cell fragments, common in the human embryo in vitro, differs in having few microvilli and numerous cytoplasmic blebs. In conclusion, there are no obvious morphological signs of regionalisation in the plasma membrane of the human embryo before the 8-cell stage.

Mouse oocyte microfilaments (MF) were perturbed by depolymerization (cytochalasin B) or stabilization (jasplakinolide) and correlated meiotic defects examined by confocal microscopy. MF, microtubules, and mitochondria were vitally stained; centrosomes (γ-tubulin), after fixation. MF depolymerization by cytochalasin in culture medium did not affect central migration of centrosomes, mitochondria, or nuclear breakdown (GVBD); some MF signal was localized around the germinal vesicle (GV). In maturation-blocking medium (containing IBMX), central movement was curtailed and cortical MF aggregations made the plasma membrane wavy. Occasional long MF suggested that not all MF were depolymerized. MF stabilization by jasplakinolide led to MF aggregations throughout the cytoplasm. GVBD occurred (unless IBMX was present) but no spindle formed. Over time, most oocytes constricted creating a dumbbell shape with MF concentrated under one-half of the oocyte cortex and on either side of the constriction. In IBMX medium, the MF-containing half of the dumbbell over time sequestered the GV, MF, mitochondria, and one to two large cortical centrosomes; the non-MF half appeared empty. Cumulus processes contacted the oocyte surface (detected by microtubule content) and mirrored MF distribution. Results demonstrated that MF play an essential role in meiosis, primarily through cortically mediated events, including centrosome localization, spindle (or GV) movement to the periphery, activation of (polar body) constriction, and establishment of oocyte polarity. The presence of a cortical “organizing pole” is hypothesized.

Polarity issues affecting III-V nitride semiconductors are reviewed with respect to their determination and control. A set of conditions crucial to the polarity control of GaN is provided for each of the following growth techniques; molecular beam epitaxy (MBE), pulsed laser deposition (PLD) and hydride vapor phase epitaxy (HVPE). Although GaN films might have been deposited by identical growth methods using the same buffer layer technologies, there is often a conflict between the resulting polarities achieved by different research groups. In this paper, we present the implications of the conditions used in each of the processes used for two-step metalorganic chemical vapor deposition (MOCVD), demonstrating systematic control of the polarity of GaN films on sapphire substrates. The potential for confusion in polarity control will be explained, taking into account the implications clarified in our studies. The correlation between the polarity and the growth conditions will be discussed in order to provide a mechanism for the determination and control of the crystal polarity during the growth of GaN films.

The polarized apical cells of Sphacelaria rigidula display a well-organized cortical F-actin cytoskeleton. This consists of bundles of actin filaments (AFs), assuming definite patterns of organization in different regions of the cell cortex. At the tip region of the apical dome the AFs appear randomly oriented, showing a diffuse fluorescence. Immediately below, at the base of the apical hemisphere, the AFs form a ring-like band around the plasmalemma transverse to the polar cell axis. The rest of the cell cortex is traversed by AFs showing an axial or slightly inclined or helical orientation. Examination of the apical cells of S. rigidula in appropriate thin sections revealed that the wall has a multi-layered structure. In the tip region of the apical dome the cell wall bears randomly oriented cellulose microfibrils (MFs), while in the basal part of the apical dome it is reinforced by a layer of densely arranged transverse MFs. As the cell grows at the apex, the transverse MFs are continuously displaced towards the cell base. Below the transverse MF layer, an additional layer with axial or slightly oblique MFs starts being depositing internally, on the tubular part of the cell. Externally to them, the layer of transversely oriented MFs remains visible. The above observations were confirmed in apical cells of S. tribuloides. MF orientation in the innermost wall layer of the apical cells coincides with that of the cortical AFs observed by fluorescence. This mutual alignment between AFs and MFs in a cell that lacks cortical microtubules (MTs) suggests that the AFs are involved in the oriented deposition of MFs. Experimental disruption of AFs with cytochalasin B caused abnormal MF deposition, a fact strongly supporting the above hypothesis. The transverse MFs forming at the base of the apical dome define the diameter and consequently the cylindrical shape of the apical cells. It is suggested that in the brown algal cells examined the AFs play a morphogenetic role similar to that of cortical microtubules in higher plant cells.

This paper describes the effects of hypomethylation with 5-azacytidine (5azaC) and dihydroxypropyladenine (DHPA) on protonemata of the moss Funaria hygrometrica Hedw. Following treatment with 5azaC or DHPA, hypomethylation of the EcoR II (CCA(T)GG) and Pst I (CTGCAG) sites in ribosomal DNA (rDNA) was confirmed using restriction enzyme analysis and Southern hybridization. Hypomethylation of the genome had profound effects on protonemal differentiation. Whilst apical cell organization and cell dimensions and shape remained unchanged, there was a marked retardation in both cytoplasmic and nuclear differentiation. Developmental abnormalities included: late and erratic side branch formation, some loss of the distinction between chloronema and caulonema, formation of aberrant buds, and loss of the potential to form brood and tmema cells after 5azaC treatment which in general had more profound effects than DHPA. Cytologically, caulonema cells were less highly polarized or unpolarized, and tended to retain small round chloroplasts, whilst nuclei in the hypomethylated protonema endoreduplicated to lower levels and tended to remain more spherical. Increased nucleolar volumes and loss of intranucleolar rDNA heterochromatin following hypomethylation might be the result of increased transcriptional activity of ribosomal RNA (rRNA) genes and drug-induced DNA decondensation, respectively. Growing hypomethylated protonema at 25°C induced extremely atypical cells and development. This temperature sensitivity and aberrations in development overall can be attributed to changes in the normal patterns of gene expression brought about by hypomethylation of gene promoter or regulator regions.

GaN, AlN and InGaN have a polar wurtzite structure and epitaxial films of these materials typically grow along the polar axis. Although the polarity of these nitrides has been studied by quite a number of techniques, many results in the literature are in conflict. In this paper an attempt is made to lay out a set of polarity assignments to provide a context for discussion of these results. A “standard framework” is proposed to correlate the disparate results, and the framework is used to draw general conclusions about the polarity of bulk crystals, VPE and MBE epitaxial films, and devices.

GaN layers deposited by MOCVD on sapphire have been characterized by Transmission Electron Microscopy (TEM). Two substrate orientations were used, (0 0 0 1) and(2 0).We determine the crystallographic structures (defect content and layer polarity) of three different types of GaN layers with different surface morphologies. Convergent Beam Electron Diffraction studies were particularly important to determine the polarity of the GaN layers. We find that polarity and surface diffusion are the factors that control the different growth modes. Unipolarity is obtained thanks to the annealing of the low temperature buffer layer or/and thanks to the nitridation of the sapphire substrate.

Hexagonal pyramids and flat tops are formed when the material has a dominant N-polarity. The pyramids contain many tiny hexagonal columnar Inversion Domains (IDs). These pyramids are formed when the tiny Ga-polar IDs grow faster than the surrounding N-polar matrix. Flat GaN layers are unipolar, with a Ga polarity. Rough grainy layers which are unipolar (Ga-polarity) are obtained when surface diffusion is not high enough.