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Notes: Background: Perforation during catheter procedures in either the atrium or ventricle is relatively uncommon, but potentially fatal if tamponade ensues. This study analyzes the occurrence and outcomes of cardiac perforation during catheter-based radiofrequency ablation procedures in the left atrium. Methods: All patients with a periprocedure perforation who have undergone radiofrequency ablation for atrial fibrillation (AF) or tachycardia were included. Results: Of 632 procedures performed from January 1999 to October 2004, 15 (2.4%) were complicated by perforation requiring pericardiocentesis. The perforation site was left atrium in 9 (60.0%), right atrium in 1 (6.7%), and right ventricle in 5 (33.3%). Intracardiac echocardiography was used in 13 (86.7%) and revealed an effusion before overt instability in 11 (73.3%). Thirteen (86.7%) patients developed a blood pressure 〈60 mmHg. The pressure stabilized in all patients after pericardiocentesis (hypotension to intervention: 10.1 ± 5.1 minutes). The total blood volume removed was 848 ± 880 mL (left atrium/right atrium: 1,074 ± 1,002 vs right ventricle: 396 ± 266, P = 0.168). Two patients required surgery to close left atrium dome perforations. The ablation was completed in 7 (46.7%) patients. Ten (66.7%) later developed early reoccurrence of AF. All patients were neurologically intact at hospital discharge. During a 1.5 ± 1.1 year follow-up, AF was eliminated (n = 4) or controlled (n = 1) in 5 (71.4%) patients with complete procedures, and 2 (20.0%) patients underwent successful repeat ablation. Conclusion: The incidence of perforation during ablation of the left atrium is low. Most perforations occur in the left atrium; however, few require surgical closure. Although less than with uncomplicated procedures, the majority of patients with complete ablations achieve long-term elimination of AF.

Notes: Introduction: Dual-chamber implantable cardioverter defibrillators (ICDs) use discriminators to differentiate between supraventricular tachycardias (SVTs) and ventricular tachycardias (VT), the accuracy of which may depend on the type and method used. ICDs can combine rate branching of tachyarrhythmias according to their A:V relationship with two SVT-VT discriminators in each rate branch, using ANY (either) or ALL (both) logic. Our goal was to determine the optimal discriminator combination. Methods: Stored electrogram data from 596 spontaneous tachyarrhythmias from 203 patients with Photon DR ICDs were analyzed. Arrhythmias are first classified by the relationship of atrial and ventricular rates (rate branches V 〈 A, V = A, and V 〉 A) followed by additional discriminators: morphology and/or sudden onset if V = A; morphology and/or interval stability if V 〈 A. Data were analyzed for all combinations of ANY and ALL logic. Results: Sensitivity and specificity were calculated for all spontaneous episodes in each analysis. V = A branch: ALL logic produced unacceptably low sensitivity, whereas morphology provided only similar sensitivity but better specificity than ANY logic. A 〉 V branch: ANY logic provided adequate sensitivity. The combination of morphology only in V = A with interval stability or morphology (ANY logic) in V 〈 A, provided the optimal result with sensitivity, specificity, positive, and negative predictive values of 99%, 79%, 87%, and 98%, respectively. Conclusion: SVT-VT combined discriminators strongly influence dual-chamber SVT-VT discrimination performance. In our study, optimal programming is morphology only in the V = A branch and morphology or interval stability (ANY) in the V 〈 A branch. ALL logic should be used with caution due to loss of sensitivity.

Notes: Abstract.  This paper examines the initial location choice of legal employment-based immigrants to the United States using Immigration and Naturalization Service data on individual immigrants, as well as economic, demographic, and social data to characterize the 298 metropolitan areas we define as the universal choice set. Focusing on interactions between place characteristics and immigrant characteristics, we provide multinomial logit model estimates for the location choices of about 38,000 employment-based immigrants to the United States in 1995, focusing on the top 10 source countries. We find that, as groups, immigrants from nearly all countries are attracted to large cities with superior climates, and to cities with relatively well-educated adults and high wages. We also find evidence that employment-based immigrants tend to choose cities where there are relatively few immigrants of nationalities other than their own. However, when we introduce interaction terms to account for the sociodemographic characteristics of the individual immigrants, we find that the estimated effects of location destination factors can reverse as one takes account of the age, gender, marital status, and previous occupation of the immigrants.

Notes: Through the 1990s hundreds of credit unions were established to serve indebted communities throughout Britain. These volunteer-run financial co-operatives did not meet growth expectations because of restrictive legislation, inadequate development models and well-intentioned but unproductive state intervention. British credit unions are more successful when they develop as market-oriented social enterprises able to build effective partnerships with banks, government and the private sector to serve low-income communities.

Notes: Developing science does depend on special individuals. But it is the cooperative and competitive interplay of many contributors that makes the whole greater than the sum of its parts. Also understanding grows temporally in fits and starts. The 1750–1848 Age of Hume–Torrens–Ricardo–J. S. Mill was stellar for trade theory. Later came the Marshall–Edgeworth–Mangoldt–Pareto Age. My generation's luck was to learn from great teachers in the Taussig–Heckscher–Cassel–Pigou–Keynes–Ohlin–Viner–Graham–Haberler age. Blessed was it to be able to bring new trends of math and graphics to crack the open questions that masters left unsolved. By 1930 the time had been over-ripe to go beyond labor-only Ricardo comparative advantage. The baton was carried forward by Lerner–Leontief–Harrod–Meade–M. Samuelson–Stolper–Samuelson–Jones–Kemp. What fun for all! What unsolved issues for post-Johnson students to gnaw at!

Notes: This review explores contemporary processes through which immigrants are categorized into shifting racial landscapes in the new Europe. Tracing the racial genealogy of the immigrant through European and Europeanist migration studies, the successive construction of overlapping tropes of the nomad, the laborer, the uprooted victim, the hybrid cosmopolite, and the (Muslim) transmigrant are examined. This history points to the perduring problematization of the immigrant as the object of national integration. If migration studies have effectively tended to racialize migrants into a new savage slot, recent ethnographies of the immigrant experience in Europe point to ways in which immigrant and diasporic groups cross racial frontiers and enact solidarity across class and cultural lines.

Notes: This review explores contemporary processes through which immigrants are categorized into shifting racial landscapes in the new Europe. Tracing the racial genealogy of the immigrant through European and Europeanist migration studies, the successive construction of overlapping tropes of the nomad, the laborer, the uprooted victim, the hybrid cosmopolite, and the (Muslim) transmigrant are examined. This history points to the perduring problematization of the immigrant as the object of national integration. If migration studies have effectively tended to racialize migrants into a new savage slot, recent ethnographies of the immigrant experience in Europe point to ways in which immigrant and diasporic groups cross racial frontiers and enact solidarity across class and cultural lines.

Notes: Abrupt climate change, such as could occur with significant thermohaline circulation (THC) weakening, appears throughout the palaeoclimate record and in many model experiments. We examine potential responses of ecosystem structure and function to the combined influence of THC collapse and greenhouse gas increase in Central England using a broad range of temperature scenarios. We demonstrate that biological communities in the North Atlantic region could be heavily influenced by THC collapse, but that the pattern of ecosystem responses depends upon the seasonal pattern of temperature changes. Plausible THC collapse scenarios threaten the remnant habitat fragments, upon which much of England's remaining biodiversity depends, by causing shifts away from the currently dominant temperate broadleaf cold deciduous tree type. Furthermore, some ecosystem responses, particularly of energy partitioning between sensible and latent heat fluxes, constitute potentially substantial feedbacks to the local climate system. However, accurate assessment of biotic responses to THC collapse requires far better confidence of the resulting seasonal temperature cycle than climate models currently provide.

Notes: An algorithm (Weather Reader) was developed and used to analyze daily weather records from all existing Canadian and American weather stations of eastern North America (in excess of 2100 stations), from 1930 through 2000. Specifically, the Weather Reader was used to compile daily minimum, mean, and maximum air temperatures for weather stations with at least 30 years of data, and was used to calculate accumulated degree days for winter thaw–freeze events relevant to yellow birch (Betula alleghaniensis Britt.) from beginning to end. A thaw–freeze event relevant to yellow birch was considered to take place when (i) the station daily maximum temperature reached or exceeded +4°C after being below freezing for at least 2 months of the winter, (ii) sufficient growing degree days accumulated (〉50 growing degree days) to cause the affected yellow birch trees to prematurely deharden, and (iii) the daily minimum temperature dropped below −4°C causing roots and/or shoots of dehardened trees to experience freeze-induced injury and possibly dieback. The threshold temperature of +4°C represents the daily temperature above which biological activity occurs in yellow birch. The station growing degree day summaries were subsequently spatially interpolated with the Kriging function in GS+™ and mapped in ArcView™ GIS in order to display the geographic extent of the most severe thaw–freeze events. The ArcView™ maps were then compared with the extent of historically observed yellow birch decline. It was found that the years 1936, 1944, and 1945 were particularly uncharacteristic in terms of region-wide winter thaw–freeze extremes, and also in terms of observed birch decline events during 1930–1960. An overlay of suspected accumulated birch decline based on thaw–freeze mapping and observed decline maps prepared by Braathe (1995), Auclair (1987), and Auclair et al. (1997) for 1930–1960 demonstrated similar geographic patterns. The thaw–freeze projection for 1930–1960 was shown to coincide with 83% of the birch decline map appearing in Braathe (1995) and 55% of the geographic range of yellow birch in eastern North America. Thaw–freeze mapping was also applied to two significant events in 1981. Greatest impact was recorded to occur mostly in southern Quebec and Ontario, and several American Great Lake States, specifically in northern Michigan and New York, where the greatest growing degree day accumulation prior to refreeze in late February (February 28th) was projected to have occurred; and in southern Quebec, most of Atlantic Canada, and Maine, prior to a late spring frost in mid-April (April 17).