Singular Monopoles from Cheshire Bows

Singular monopoles are nonabelian monopoles with prescribed Dirac-type singularities. All of them are delivered by the Nahm's construction. In practice, however, the effectiveness of the latter is limited to the cases of one or two singularities. We present an alternative construction of singular monopoles formulated in terms of Cheshire bows. To illustrate the advantages of our bow construction we obtain an explicit expression for one U(2) gauge group monopole with any given number of singularities of Dirac type.Comment: LaTeX, 34 pages, 8 figure

WISP genes are members of the connective tissue growth factor family that are up-regulated in Wnt-1-transformed cells and aberrantly expressed in human colon tumors

Wnt family members are critical to many developmental processes, and components of the Wnt signaling pathway have been linked to tumorigenesis in familial and sporadic colon carcinomas. Here we report the identification of two genes, WISP-1 and WISP-2, that are up-regulated in the mouse mammary epithelial cell line C57MG transformed by Wnt-1, but not by Wnt-4. Together with a third related gene, WISP-3, these proteins define a subfamily of the connective tissue growth factor family. Two distinct systems demonstrated WISP induction to be associated with the expression of Wnt-1. These included (i) C57MG cells infected with a Wnt-1 retroviral vector or expressing Wnt-1 under the control of a tetracyline repressible promoter, and (ii) Wnt-1 transgenic mice. The WISP-1 gene was localized to human chromosome 8q24.1-8q24.3. WISP-1 genomic DNA was amplified in colon cancer cell lines and in human colon tumors and its RNA overexpressed (2- to >30-fold) in 84% of the tumors examined compared with patient-matched normal mucosa. WISP-3 mapped to chromosome 6q22-6q23 and also was overexpressed (4- to >40-fold) in 63% of the colon tumors analyzed. In contrast, WISP-2 mapped to human chromosome 20q12-20q13 and its DNA was amplified, but RNA expression was reduced (2- to >30-fold) in 79% of the tumors. These results suggest that the WISP genes may be downstream of Wnt-1 signaling and that aberrant levels of WISP expression in colon cancer may play a role in colon tumorigenesis

Fluctuating Elastic Rings: Statics and Dynamics

We study the effects of thermal fluctuations on elastic rings. Analytical expressions are derived for correlation functions of Euler angles, mean square distance between points on the ring contour, radius of gyration, and probability distribution of writhe fluctuations. Since fluctuation amplitudes diverge in the limit of vanishing twist rigidity, twist elasticity is essential for the description of fluctuating rings. We find a crossover from a small scale regime in which the filament behaves as a straight rod, to a large scale regime in which spontaneous curvature is important and twist rigidity affects the spatial configurations of the ring. The fluctuation-dissipation relation between correlation functions of Euler angles and response functions, is used to study the deformation of the ring by external forces. The effects of inertia and dissipation on the relaxation of temporal correlations of writhe fluctuations, are analyzed using Langevin dynamics.Comment: 43 pages, 9 Figure

Understanding person acquisition using an interactive activation and competition network

Face perception is one of the most developed visual skills that humans display, and recent work has attempted to examine the mechanisms involved in face perception through noting how neural networks achieve the same performance. The purpose of the present paper is to extend this approach to look not just at human face recognition, but also at human face acquisition. Experiment 1 presents empirical data to describe the acquisition over time of appropriate representations for newly encountered faces. These results are compared with those of Simulation 1, in which a modified IAC network capable of modelling the acquisition process is generated. Experiment 2 and Simulation 2 explore the mechanisms of learning further, and it is demonstrated that the acquisition of a set of associated new facts is easier than the acquisition of individual facts in isolation of one another. This is explained in terms of the advantage gained from additional inputs and mutual reinforcement of developing links within an interactive neural network system. <br/

South African food allergy consensus document 2014

The prevalence of food allergy is increasing worldwide and is an important cause of anaphylaxis. There are no local South African food allergy guidelines. This document was devised by the Allergy Society of South Africa (ALLSA), the South African Gastroenterology Society (SAGES) and the Association for Dietetics in South Africa (ADSA). Subjects may have reactions to more than one food, and different types and severity of reactions to different foods may coexist in one individual. A detailed history directed at identifying the type and severity of possible reactions is essential for every food allergen under consideration. Skin-prick tests and specific immunoglobulin E (IgE) (ImmunoCAP) tests prove IgE sensitisation rather than clinical reactivity. The magnitude of sensitisation combined with the history may be sufficient to ascribe causality, but where this is not possible an incremental oral food challenge may be required to assess tolerance or clinical allergy. For milder non-IgE-mediated conditions a diagnostic elimination diet may be followed with food re-introduction at home to assess causality. The primary therapy for food allergy is strict avoidance of the offending food/s, taking into account nutritional status and provision of alternative sources of nutrients. Acute management of severe reactions requires prompt intramuscular administration of adrenaline 0.01 mg/kg and basic resuscitation. Adjunctive therapy includes antihistamines, bronchodilators and corticosteroids. Subjects with food allergy require risk assessment and those at increased risk for future severe reactions require the implementation of risk-reduction strategies, including education of the patient, families and all caregivers (including teachers), the provision of a written emergency action plan, a MedicAlert necklace or bracelet and injectable adrenaline (preferably via auto-injector) where necessary.http://www.samj.org.zaam2016Paediatrics and Child Healt

Epidemiology of IgE-mediated food allergy

Despite the large number of foods that may cause immunoglobulin E (IgE)-mediated reactions, most prevalence studies have focused on the most common allergenic foods, i.e. cow’s milk, hen’s egg, peanut, tree nut, wheat, soya, fish and shellfish. Food allergy peaks during the first two years of life, and then diminishes towards late childhood as tolerance to several foods develops. Based on meta-analyses and large population-based studies, the true prevalence of food allergy varies from 1% to >10%, depending on the geographical area and age of the patient. The prevalence of food allergy in South Africa (SA) is currently being studied. The prevalence of IgE-mediated food allergy in SA children with moderate-to-severe atopic dermatitis is 40%; however, this represents a high-risk population for food allergy. Preliminary data from the South African Food Sensitisation and Food Allergy (SAFFA) study, which is investigating food allergy in an unselected cohort of 1 - 3-year olds, show a prevalence of 11.6% sensitisation to common foods. Food allergy was most common to egg (1.4%) and peanut (1.1%). Food allergy appears to be the most common trigger of anaphylactic reactions in the community, especially in children, in whom food is responsible for ≥85% of such reactions. In adults, shellfish and nut, and in children, peanut, tree nut, milk and egg, are the most common triggers of food-induced anaphylaxis.http://www.samj.org.zahb201

Vaccination in food allergic patients

Important potential food allergens in vaccines include egg and gelatin. Rare cases of reactions to yeast, lactose and casein have been reported. It is strongly recommended that when vaccines are being administered resuscitation equipment must be available to manage potential anaphylactic reactions, and that all patients receiving a vaccine are observed for a sufficient period. Children who are allergic to egg may safely receive the measles-mumps-rubella (MMR) vaccine; it may also be given routinely in primary healthcare settings. People with egg allergy may receive influenza vaccination routinely; however, some authorities still perform prior skinprick testing and give two-stage dosing. The purified chick embryo cell culture rabies vaccine contains egg protein, and therefore the human diploid cell and purified verocell rabies vaccines are preferred in cases of egg allergy. Yellow fever vaccine has the greatest likelihood of containing amounts of egg protein sufficient to cause an allergic reaction in allergic individuals. This vaccine should not be routinely administered in egg allergic patients and referral to an allergy specialist is recommended, as vaccination might be possible after careful evaluation, skin-testing and graded challenge or desensitisation.http://www.samj.org.zahb201

Severe food allergy and anaphylaxis : treatment, risk assessment and risk reduction

An anaphylactic reaction may be fatal if not recognised and managed appropriately with rapid treatment. Key steps in the management of anaphylaxis include eliminating additional exposure to the allergen, basic life-support measures and prompt intramuscular administration of adrenaline 0.01 mg/kg (maximum 0.5 mL). Adjunctive measures include nebulised bronchodilators for lower-airway obstruction, nebulised adrenaline for stridor, antihistamines and corticosteroids. Patients with an anaphylactic reaction should be admitted to a medical facility so that possible biphasic reactions may be observed and risk-reduction strategies initiated or reviewed after recovery from the acute episode. Factors associated with increased risk of severe reactions include co-existing asthma (and poor asthma control), previous severe reactions, delayed administration of adrenaline, adolescents and young adults, reaction to trace amounts of foods, use of non-selective β-blockers and patients who live far from medical care. Risk-reduction measures include providing education with regard to food allergy and a written emergency treatment plan on allergen avoidance, early symptom recognition and appropriate emergency treatment. Risk assessment allows stratification with provision of injectable adrenaline (preferably via an auto-injector) if necessary. Patients with ambulatory adrenaline should be provided with written instructions regarding the indications for and method of administration of this drug and trained in its administration. Patients and their caregivers should be instructed about how to avoid foods to which the former are allergic and provided with alternatives. Permission must be given to inform all relevant caregivers of the diagnosis of food allergy. The patient must always wear a MedicAlert necklace or bracelet and be encouraged to join an appropriate patient support organisation.http://www.samj.org.zahb201

Exclusion diets and challenges in the diagnosis of food allergy

Instituting an exclusion diet for 2 - 6 weeks, and following it up with a planned and intentional re-introduction of the diet, is important for the diagnosis of a food allergy when a cause-and-effect relationship between ingestion of food and symptoms is unclear. Food may be re-introduced after (short-term) exclusion diets for mild-to-moderate non-immunoglobulin E (IgE)-mediated conditions in a safe clinical environment or cautiously at home. However, patients who have had an IgE-mediated immediate reaction to food, a previous severe non-IgE-mediated reaction or a long period of food exclusion should not have a home challenge, but rather a formal incremental food challenge protocol in a controlled setting. An incremental oral food challenge (OFC) test is the gold standard to diagnose clinical food allergy or demonstrate tolerance. It consists of gradual feeding of the suspected food under close observation. It should be done by trained practitioners in centres that have experience in performing the procedure in an appropriate setting. An OFC must be performed in a setting where resuscitation equipment is available in the event of a severe anaphylactic reaction. OFCs are terminated when a reaction becomes apparent. Standardised and pre-set criteria are available on when to discontinue challenges. Patients who tolerate the full dose ‘pass’ the challenge and are advised to eat a full portion of the food at least twice a week to maintain tolerance. Those who have reactions have ‘failed’ the challenge, should avoid the food, receive education and implement risk-reduction strategies where appropriate. Patients should be observed for a minimum of 2 hours following a negative challenge and for 4 hours after a positive one.http://www.samj.org.zahb201