Polarization Drift Channel Model for Coherent Fibre-Optic Systems

A theoretical framework is introduced to model the dynamical changes of the state of polarization during transmission in coherent fibre-optic systems. The model generalizes the one-dimensional phase noise random walk to higher dimensions, accounting for random polarization drifts, emulating a random walk on the Poincar\'e sphere, which has been successfully verified using experimental data. The model is described in the Jones, Stokes and real four-dimensional formalisms, and the mapping between them is derived. Such a model will be increasingly important in simulating and optimizing future systems, where polarization-multiplexed transmission and sophisticated digital signal processing will be natural parts. The proposed polarization drift model is the first of its kind as prior work either models polarization drift as a deterministic process or focuses on polarization-mode dispersion in systems where the state of polarization does not affect the receiver performance. We expect the model to be useful in a wide-range of photonics applications where stochastic polarization fluctuation is an issue.Comment: 15 pages, 4 figure

The endometrial capillaries during the normal menstrual cycle: a morphometric study

The areas of the capillary lumen, the entire capillary, the endothelial cells and the adventitia, as well as the thickness of the endothelial cell layer and the adventitia were studied using morphometric methods in endometrial samples from 34 fertile women who had a hormonal profile compatible with normal ovarian function. The biopsies were grouped around the luteinizing hormone surge. The results were calculated as mean values of 72-h periods and related to the mean levels of oestradiol and progesterone circulating in plasma 72 h prior to the biopsy. The results indicated that the sub-epithelial capillary plexus of the human endometrium undergoes dynamic changes during the normal menstrual cycle with a significant dilatation of the vessels during the post-ovulatory phase. A significant correlation was found between the area of the capillary lumen and the mean level of progesterone circulating in the plasma 72 h prior to the biopsy (P = 0.037). We conclude that the ovarian steroids produced during the normal menstrual cycle are likely to influence sub-epithelial vascularization causing dilatation in the post-ovulatory phase. This dilatation of the sub-epithelial capillaries may be related to the development of oedema appearing in the stroma at the time of the expected implantation. The possible functional significance of the capillary dilatation in terms of implantation, however, needs to be further investigate

Social Capital Impediments In The United Arab Emirates: A Case Of Emirati Female Entrepreneurs

It is possible that when looked at from the outside, the Gulf Arab countries give an impression that they are not very supportive to female entrepreneurs. This perception may be pertinent to a certain degree; however, Emirati female entrepreneurs (EFE) in the United Arab Emirates demonstrate that enhancing co-operation and support is possible through increasing interaction and networking with men. Analysis is undertaken of the observations and actions of conveniently selected 17 EFEs. The scoping of the respondents reveal that EFEs who engage with indirect male ties require a \u27male contact facilitator\u27 from their family or relatives to do so. These men are facilitated by the entrepreneur to adopt the role of a \u27male network partner (MNP) and provide support in overcoming challenges and achieving business objectives. The paper sets new standards of support for Emirati women in business ventures as it attempts to describe Emirati female entrepreneurship in a different language and proposes that co-operation, interaction and networking with men help EFEs access and use key resources, alleviate or remove key challenges and achieve business objectives

The effect of RU486 administered during the proliferative and secretory phase of the cycle on the bleeding pattern, hormonal parameters and the endometrium

Seventeen healthy women aged 24-45 years with regular menstrual periods, proven fertility and not using steroidal contraceptives or IUD were recruited for the study. The volunteers were followed during one control, one treatment and one follow-up cycle. Daily morning urine samples were obtained during the control and the treatment cycle. The samples were analysed with regard to pregnanediol glucuronide (P2-G), oestrone glucuronide (E1-G), oestradiol (E2), progesterone (P4), LH and creatinine. During the entire 3-month study the subjects kept a record of uterine bleeding and side effects. The subjects received 50 mg RU486 daily either on cycle days 7-10 (n = 7) or on cycle days 20-23 (n = 10). An endometrial biopsy was taken on cycle day 10 in the first group and on cycle days 21-28 in the second group of patients. Treatment during the proliferative phase caused significant prolongation of the cycle length due to a delay of the oestrogen and LH surge. However, once the oestrogen concentration started to increase, the remaining part of the cycle was normal. The length of the follow-up cycle was similar to that of the control cycle. The morphology of the endometrium did not differ from control samples taken from untreated women at the same time of the cycle. All ovulating women (n = 9) treated in the mid-luteal phase started to bleed on the 3rd to 4th day of the treatment. In four of these women the bleeding was scanty and followed by a menstrual-like bleeding at expected time, while in the remaining five volunteers the treatment bleeding was heavier and not followed by a new bleeding until a month later. The duration of the secretory phase was 16.5 ± 1.3 days in women with two bleeding episodes and 11.8 ± 1.9 days in women with one bleeding episode (P < 0.05). The hormonal parameters were similar in both groups up to the start of the treatment. In the patients with one bleeding episode, the treatment was associated with a reduction in progesterone concentration, while in the patients with two bleeding episodes the progesterone concentration remained elevated until the second bleeding episode. Light microscopic examination of the endometrium revealed unique changes in the endometrial morphology. The results indicate that RU486 acts mainly on the endometrium but a direct or indirect effect on the corpus luteum cannot be excluded. The age of the corpus luteum may be of importance for its susceptibility to RU486 treatmen

Towards a ‘Long View’: Historical Perspectives on the Scaling and Replication of Social Ventures

Social ventures are now widely regarded as playing an essential role in addressing persistent and pervasive societal challenges. This insight has prompted an active search for readily-scaleable and replicable business models. However, relatively little consideration has been given to the longer-term growth and performance of these hybrid organizational forms. This paper examines how historically-informed research might enhance our understanding of growth processes. It considers the conceptualization of organizational growth in social ventures and the relevance of prevailing constructs. The explanatory potential of ‘long view’ approaches examined by applying three constructs, opportunity recognition, entrepreneurial adjustment, and institutional structure, in a comparative historical analysis of two British social ventures

Re-inventing artisanal knowledge and practice: a critical review of innovation in a craft-based industry

This paper presents a critical review of the ways in which the specialised knowledge and working practices of craft-based industries have been transformed in the context of broader processes of industrialisation and global competition. The opening section makes the case for artisanal knowledge as a ‘Cinderella’ subject that remains important yet largely uncharted territory for innovation researchers. It is followed by a critical review of existing empirical and theoretical studies that have examined the reproduction and reinvention of artisanal knowledge. The review concludes that valuable insights remain obscured due to the way in which this literature is distributed across discrete disciplines with little evidence of cross-fertilisation or integration. Several common themes emerge, which provide the basis for an outline theoretical framework. The central arguments are illustrated with reference to a case-based analysis of the technological and social innovations that have taken place in English farmhouse cheesemaking over an extended period, from the pre-industrial era to the beginning of the present century. The concluding section considers how more nuanced understandings of artisanal knowledge and practice might enhance innovation theory and contribute to the continued flourishing of craft-based industries