Spectrophotometric method for determination of ozone in aqueous solutions

A sensitive spectrophotometric method for determination of ozone in small volumes of water is presented. It was performed in order to meet the requirements of a kinetic study of virus and bacteria inactivation by ozone.The proposed method involves oxidation of a buffered iodine solution and spectrophotometric measurement of the triiodide ion liberated by ozone. Two procedures are used: one for low ozone concentration (0·01–0·30 ppm) and another for higher concentrations (0·30–2·0 ppm). The reproducibility of results is very high when the procedure used corresponds with the ozone level for which it is intended.This spectrophotometric method is compared with the standard volumetric method and the differences are presented and discussed.Some applications of the method for a kinetic study of virus inactivation by ozone are presented.     

Rethinking cities in the Middle East: political economy, planning, and the lived space

Urbanisation is an economic, political, and socio-cultural complexity, and so is its interaction with cityscapes. However, this truism rarely finds an expression in academic research. It is obvious that economic transitions would determine the quality and volume of the built environment. Municipal and state decision making further shape the nature of urban spaces, and socio-cultural transformations influence perceived notions of the lived space and, in turn, reshape the physical landscape itself. Nevertheless, research on cities in the Middle East and elsewhere remains fairly limited in scope, with little cross-discipline 'conversation' among scholars in different fields which attempts to account for such complexity. This is all the more surprising as life in cities has become, over the past half century or so, the most significant form of human collective dwelling; in the Middle East over half the population currently lives in urban settings and the numbers are forecast to grow in the future.1

This review article is the result of a dialogue between an architect and an economic historian in response to the foregoing. We have united in an attempt to offer a more integrative approach to Middle East urbanism, accounting for the interactions of the political economy of this region, planning, and the lived space. The key questions on which we focus are why and how do state transformation and economic structural change impact upon urban space. In seeking the answers we examine the long-term trajectory of cities as they went through the first period of globalisation under imperial intervention and/or direct colonial rule; gradually came under independent, inward-looking, national regimes; and presently experience the second wave of globalisation and the opening of local economies to international markets. Such a narrative explores common themes in the historical trajectories of cities' lives.

Our long-term, geographically extensive overview (Map 1) is bound to miss some specific developments that have made a significant impact on the transformations of cities in the region; our aim is not to totalise Middle East experiences and reduce a variety of narratives to a simplistic linear model of change. Even more so, our study of the Middle East is mostly focused on Egypt, the Asian Arab countries (the mashraq), Israel/Palestine, and Turkey, the geographical unit which roughly corresponded with the Ottoman Empire, the last state to control the Middle East before the age of nations. We acknowledge that any bird's eye view perspective is bound to do some injustice to historically specific contexts, and city transitions that occurred in such contexts. We would welcome any future work that brings our suggestion here, namely to integrate political economy with the study of urban development and city life, to bear on more specific research on urbanism in the Middle East.     

Prospective motion correction of X-ray images for coronary interventions

A method for prospective motion correction of X-ray imaging of the heart is presented. A 3D + t coronary model is reconstructed from a biplane coronary angiogram obtained during free breathing. The deformation field is parameterized by cardiac and respiratory phase, which enables the estimation of the state of the arteries at any phase of the cardiac-respiratory cycle. The motion of the three-dimensional (3-D) coronary model is projected onto the image planes and used to compute a dewarping function for motion correcting the images. The use of a 3-D coronary model facilitates motion correction of images acquired with the X-ray system at arbitrary orientations. The performance of the algorithm was measured by tracking the motion of selected left coronary landmarks using a template matching cross-correlation. In three patients, we motion corrected the same images used to construct their 3D + t coronary model. In this best case scenario, the algorithm reduced the motion of the landmarks by 84%-85%, from mean RMS displacements of 12.8-14.6 pixels to 2.1-2.2 pixels. Prospective motion correction was tested in five patients by building the coronary model from one dataset, and correcting a second dataset. The patient's cardiac and respiratory phase are monitored and used to calculate the appropriate correction parameters. The results showed a 48%-63% reduction in the motion of the landmarks, from a mean RMS displacement of 11.5-13.6 pixels to 4.4-7.1 pixels.     

Rethinking cities in the Middle East: political economy,planning, and the lived space

Urbanisation is an economic, political, and socio-cultural complexity, and so is its interaction with cityscapes. However, this truism rarely finds an expression in academic research. It is obvious that economic transitions would determine the quality and volume of the built environment. Municipal and state decision making further shape the nature of urban spaces, and socio-cultural transformations influence perceived notions of the lived space and, in turn, reshape the physical landscape itself. Nevertheless, research on cities in the Middle East and elsewhere remains fairly limited in scope, with little cross-discipline ‘conversation’ among scholars in different fields which attempts to account for such complexity. This is all the more surprising as life in cities has become, over the past half century or so, the most significant form of human collective dwelling; in the Middle East over half the population currently lives in urban settings and the numbers are forecast to grow in the future.1 1. The authors thank Kerem Oktem and Kobi Peled for their insightful comments on an earlier version of this article.

This review article is the result of a dialogue between an architect and an economic historian in response to the foregoing. We have united in an attempt to offer a more integrative approach to Middle East urbanism, accounting for the interactions of the political economy of this region, planning, and the lived space. The key questions on which we focus are why and how do state transformation and economic structural change impact upon urban space. In seeking the answers we examine the long-term trajectory of cities as they went through the first period of globalisation under imperial intervention and/or direct colonial rule; gradually came under independent, inward-looking, national regimes; and presently experience the second wave of globalisation and the opening of local economies to international markets. Such a narrative explores common themes in the historical trajectories of cities' lives.

Our long-term, geographically extensive overview (Map 1) is bound to miss some specific developments that have made a significant impact on the transformations of cities in the region; our aim is not to totalise Middle East experiences and reduce a variety of narratives to a simplistic linear model of change. Even more so, our study of the Middle East is mostly focused on Egypt, the Asian Arab countries (the mashraq), Israel/Palestine, and Turkey, the geographical unit which roughly corresponded with the Ottoman Empire, the last state to control the Middle East before the age of nations. We acknowledge that any bird's eye view perspective is bound to do some injustice to historically specific contexts, and city transitions that occurred in such contexts. We would welcome any future work that brings our suggestion here, namely to integrate political economy with the study of urban development and city life, to bear on more specific research on urbanism in the Middle East.     

Three-dimensional motion tracking of coronary arteries in biplane cineangiograms

A three-dimensional (3-D) method for tracking the coronary arteries through a temporal sequence of biplane X-ray angiography images is presented. A 3-D centerline model of the coronary vasculature is reconstructed from a biplane image pair at one time frame, and its motion is tracked using a coarse-to-fine hierarchy of motion models. Three-dimensional constraints on the length of the arteries and on the spatial regularity of the motion field are used to overcome limitations of classical two-dimensional vessel tracking methods, such as tracking vessels through projective occlusions. This algorithm was clinically validated in five patients by tracking the motion of the left coronary tree over one cardiac cycle. The root mean square reprojection errors were found to be submillimeter in 93% (54/58) of the image pairs. The performance of the tracking algorithm was quantified in three dimensions using a deforming vascular phantom. RMS 3-D distance errors were computed between centerline models tracked in the X-ray images and gold-standard centerline models of the phantom generated from a gated 3-D magnetic resonance image acquisition. The mean error was 0.69 (+/- 0.06) mm over eight temporal phases and four different biplane orientations.     

A novel assay for evaluating glycogenolysis in rat adipocytes and the inability of insulin to antagonize glycogenolysis in this cell type

We report here on a novel procedure for measuring glycogenolysis in rat adipocytes. In this procedure, cells are incubated for 30 min at 37 degrees C with insulin or vanadate, and with [U-14C]glucose to label the glycogen pool with radioactive glucose. The cells are washed and preincubated for an additional 1 h, before being assayed. The extent of glycogenolysis is determined by the decrease in radioactivity in precipitated glycogen, which was quite substantial under experimental conditions facilitating glycogenolysis. From the assay, we determined the following. (a) Glycogenolysis is activated in rat adipocytes in response to lipolytic hormones (i.e. catecholamines and adrenocorticotropic hormone). (b) Other agents and conditions elevating intracellular adenosine 3',5'-monophosphate levels (i.e. cholera toxin, dibutyryladenosine 3',5'-monophosphate, and isobutylmethylxanthine) also activate glycogenolysis. (c) Glycogenolysis (as opposed to lipolysis) is activated at concentrations of adrenocorticotropic hormone or isoproterenol 7-11-fold lower and at adenosine 3',5'-monophosphate concentrations 7-fold lower. (d) Calyculin A, a specific inhibitor of protein phosphatase 1, activates glycogenolysis as well. Calyculin A also activates lipolysis at an equimolar potency. (e) Insulin does not antagonize glycogenolysis in rat adipocytes. In conclusion, the assay allowed us to compare glycogenolysis to lipolysis within the same cell, and to find that the sensitivity to hormones and adenosine 3',5'-monophosphate was about 1 order of magnitude higher for glycogenolysis than for lipolysis. A more striking finding was the inability of insulin to antagonize glycogenolysis in the rat adipose cell, an effect which occurs readily in liver and muscle cells via protein phosphatase 1-activating machinery. This rules out a role for adipose protein phosphatase 1 activation in the mechanism by which insulin antagonizes lipolysis and supports the contention that the insulin effect in lowering adenosine 3',5'-monophosphate levels is the central mechanism by which insulin antagonizes lipolysis.     

Quantitation of methionyl peptides in nanomole quantities by a fluorometric method

A quantitative and highly specific method to determine low concentrations of methionyl peptides, which do not contain tryptophan or cysteine residues, has been developed. The method is based on the stoichiometry and selectivity of N-chlorosuccinimide (NCS) towards methionine and N-acetyltryptophan. N-Chlorosuccinimide reacts with N-acetyltryptophan in a 1:1 ratio to produce the N-acetyl-2-oxindolealanine--a derivative essentially devoid of fluorescence. The decrease in fluorescence intensity is approximately linear with respect to the NCS concentration. Preincubation of NCS with methionine or methionyl peptide consumes a stoichiometric amount of the reagent and the unreacted NCS is quantitated by the decrease in fluorescence intensity resulting upon incubation of the mixture with 1 eq of N-acetyltryptophan. Less than 1 nmol of methionyl peptide can be accurately quantitated by this method.