(Table 1) Age control and temporal resolution of paleoceanographic records of the North Atlantic

Short-term changes in sea surface conditions controlling the thermohaline circulation in the northern North Atlantic are expected to be especially efficient in perturbing global climate stability. Here we assess past variability of sea surface temperature (SST) in the northeast Atlantic and Norwegian Sea during Marine Isotope Stage (MIS) 2 and, in particular, during the Last Glacial Maximum (LGM). Five high-resolution SST records were established on a meridional transect (53°N-72°N) to trace centennial-scale oscillations in SST and sea-ice cover. We used three independent computational techniques (SIMMAX modern analogue technique, Artificial Neural Networks (ANN), and Revised Analog Method (RAM)) to reconstruct SST from planktonic foraminifer census counts. SIMMAX and ANN reproduced short-term SST oscillations of similar magnitude and absolute levels, while RAM, owing to a restrictive analog selection, appears less suitable for reconstructing "cold end" SST. The SIMMAX and ANN SST reconstructions support the existence of a weak paleo-Norwegian Current during Dansgaard-Oeschger (DO) interstadials number 4, 3, 2, and 1. During the LGM, two warm incursions of 7°C water to occurred in the northern North Atlantic but ended north of the Iceland Faroe Ridge. A rough numerical estimate shows that the near-surface poleward heat transfer from 53° across the Iceland-Faroe Ridge up to to 72° N dropped to less than 60% of the modern value during DO interstadials and to almost zero during DO stadials. Summer sea ice was generally confined to the area north of 70°N and only rarely expanded southward along the margins of continental ice sheets. Internal LGM variability of North Atlantic (>40°N) SST in the GLAMAP 2000 compilation (Sarnthein et al., 2003, doi:10.1029/2002PA000771; Pflaumann et al., 2003, doi:10.1029/2002PA000774) indicates maximum instability in the glacial subpolar gyre and at the Iberian Margin, while in the Nordic Seas, SST was continuously low.

Core scans and lithologic analysis of Subglacial Lake Whillans sediment cores

The hydrologic system beneath the Antarctic Ice Sheet is thought to influence both the dynamics and distribution of fast flowing ice streams, which discharge most of the ice lost by the ice sheet. Despite considerable interest in understanding this subglacial network and its affect on ice flow, in situ observations from the ice sheet bed are exceedingly rare. Here we describe the first sediment cores recovered from an active subglacial lake. The lake, known as Subglacial Lake Whillans, is part of a broader, dynamic hydrologic network beneath the Whillans Ice Stream in West Antarctica. Even though "floods" pass through the lake, the lake floor shows no evidence of erosion or deposition by flowing water. By inference, these floods must have insufficient energy to erode or transport significant volumes of sediment coarser than silt. Consequently, water flow beneath the region is probably incapable of incising continuous channels into the bed and instead follows preexisting subglacial topography and surface slope. Sediment on the lake floor consists of till deposited during intermittent grounding of the ice stream following flood events. The fabrics within the till are weaker than those thought to develop in thick deforming beds suggesting subglacial sediment fluxes across the ice plain are currently low and unlikely to have a large stabilizing effect on the ice stream's grounding zone.

Enviromagnetic, major element, and grain-size analyses of surface sediment samples along the continental margin between East Brazil and Patagonia

Continental margin sediments of SE South America originate from various terrestrial sources, each conveying specific magnetic and element signatures. Here, we aim to identify the sources and transport characteristics of shelf and slope sediments deposited between East Brazil and Patagonia (20°-48°S) using enviromagnetic, major element, and grain-size data. A set of five source-indicative parameters (i.e., chi-fd%, ARM/IRM, S0.3T, SIRM/Fe and Fe/K) of 25 surface samples (16-1805 m water depth) was analyzed by fuzzy c-means clustering and non-linear mapping to depict and unmix sediment-province characteristics. This multivariate approach yields three regionally coherent sediment provinces with petrologically and climatically distinct source regions. The southernmost province is entirely restricted to the slope off the Argentinean Pampas and has been identified as relict Andean-sourced sands with coarse unaltered magnetite. The direct transport to the slope was enabled by Rio Colorado and Rio Negro meltwaters during glacial and deglacial phases of low sea level. The adjacent shelf province consists of coastal loessoidal sands (highest hematite and goethite proportions) delivered from the Argentinean Pampas by wave erosion and westerly winds. The northernmost province includes the Plata mudbelt and Rio Grande Cone. It contains tropically weathered clayey silts from the La Plata Drainage Basin with pronounced proportions of fine magnetite, which were distributed up to ~24° S by the Brazilian Coastal Current and admixed to coarser relict sediments of Pampean loessoidal origin. Grain-size analyses of all samples showed that sediment fractionation during transport and deposition had little impact on magnetic and element source characteristics. This study corroborates the high potential of the chosen approach to access sediment origin in regions with contrasting sediment sources, complex transport dynamics, and large grain-size variability.

Advertisement and society in graphic magazine: La Esfera (1920-1930)

In the first third of the 20th century, Spain entered into modernity thanks to the positive state of its economic, cultural and social domains after the First World War. The objective of this article is to understand the role of artistic advertisements in the transformation of Spanish society that occurred during the decade of the ‘20s. My study of the illustrated magazine La Esfera has revealed that illustrated advertisements spread fashion, fostered sports and outdoors life, created the habit of smoking among women and had an educational influence that was powerful enough to change hygienic practices among children.

The Electoral Rise of Populist Radical Right Parties in Europe: Ideological Parameters and Social Motivations

Populist radical right parties have become major political actors in Europe. This paper analyses the path and the different phases that have led them from the fringes of public debate to their present signifi cance, which is based on their capacity to attract electoral support and infl uence the political agendas in their respective countries. Besides, an analysis of the core ideological beliefs of these parties, and of the topics on which their mobilization capacity rests, is provided, as well as of the type of voters that are attracted by them. Finally, the authors discuss the meaning and impact of the growing popularity of the ideas and proposals put forward by the populist radical right parties.

Antropología de la Conservación en España. Balance y perspectivas

En este artículo presentamos un balance de la Antropología de la Conservación en el Estado español. Durante las últimas décadas, la protección de los espacios naturales ha aumentado de una manera exponencial en todo el mundo. A la vez que se extendía esta patrimonialización de la naturaleza, los trabajos etnográficos sobre las áreas protegidas han ido ganando terreno dentro de la disciplina y, en particular, en el campo de la Antropología Ambiental. La mencionada bibliografía ha puesto de relieve los múltiples aspectos derivados de las nuevas políticas territoriales de regulación, apropiación y mercantilización de la ‘naturaleza’. En este trabajo realizamos una revisión exhaustiva de la producción generada a raíz de este interés por las áreas protegidas en nuestro país subrayando sus principales aportaciones, características y debilidades. De este modo pretendemos reflexionar acerca de su continuidad, con el fin de evitar la mera reiteración y favorecer el avance en sus resultados.

What is this thing called Historical Archaeology?

Historical archaeology, in its narrow temporal sense -as an archaeology of the emergence and subsequent evolution of the Modern world- is steadily taking pace in Spanish academia. This paper aims at provoking a more robust debate through understanding how Spanish historical archaeology is placed in the international scene and some of its more relevant particularities. In so doing, the paper also stresses the strong links that have united historical and prehistorical archaeology since its inception, both in relation to the ontological, epistemological and methodological definition of the first as to the influence of socio-political issues in the latter. Such reflection is partly a situated reflection from prehistory as one of the paper’s authors has been a prehistorian for most of her professional life.

¿Fue la crisis política del Occidente musulmán del siglo XIII debida a un cambio climático? Una aproximación histórica al fin del Periodo Cálido Medieval

Durante el siglo XIII se produjo una sucesión de revueltas que supuso la desaparición del Imperio almohade y su sustitución por poderes regionales en al-Andalus, el Magreb y el Magreb al-Aqsà. La historiografía ha presentado el surgimiento y pugna entre estos poderes como un fenómeno social, político e, incluso, cultural y religioso, con el que se ha podido explicar su aniquilación o marginalización. Este trabajo pretende contextualizar los hechos desde una perspectiva medioambiental, de forma que la desintegración del califato almohade, el surgimiento de aquellos poderes y la progresión de los reinos cristianos en la península ibérica puedan entenderse desde una visión global de cambio climático y una posible crisis agrícola.

Emisiones de gases de efecto invernadero en el humedal natural El Madrigal

En la presente investigaci?n se estudi? la din?mica de la generaci?n y captura de las emisiones de gases de efecto invernadero (GEI) en un humedal natural eutrofizado bajo condiciones tropicales denominado El Madrigal, ubicado en la vereda El Madrigal, del municipio de Riofr?o, Valle del Cauca. Con tal prop?sito se evalu? la variaci?n espacial de las emisiones de los GEI tales como metano (CH4), di?xido de carbono (CO2) y ?xido nitroso (N2O) y se estableci? su posible correlaci?n con par?metros de calidad de agua como pH, ox?geno disuelto, potencial de ?xido reducci?n, alcalinidad, fosfatos, nitratos entre otros y a su vez con el contenido de materia org?nica y nutrientes presente en los sedimentos. En este sentido, se determinaron y compararon las emisiones en cuatro puntos de muestreo establecidos en el humedal con caracter?sticas diferentes: P1 (Zona de intercambio de agua y sedimentos con R?o Cauca), P2 (Zona influenciada por actividades pisc?colas), P3 (Zona influenciada por vertimientos de aguas residuales y presencia de vegetaci?n) y P3A (Zona sin cobertura vegetal). En cada punto se realizaron mediciones de gases de efecto invernadero, par?metros in situ, calidad de agua y, sedimentos. Los valores de flux obtenidos evidenciaron que el humedal El Madrigal actu? como fuente y sumidero de gases de efecto invernadero durante todo el per?odo de muestreo. El punto P1 present? flux promedios de -1,96 ? 3,10 g.CH4.m-2 d-1; -0,12 ? 7,63 g.CO2.m-2 d-1 y 1,73 ? 5,75 mg.N2O.m-2 d-1. Para el caso del punto P2 se obtuvieron flux promedios de 0,898 ? 1,27 g.CH4.m-2 d-1; 1,03 ? 9,31 g.CO2.m-2 d-1 y -1,19 ? 5,08 mg.N2O.m-2 d-1. Por su parte el punto P3 evidenci? flux promedios de 3,08 ? 3,99 g.CH4.m-2 d-1; -2,74 ? 9,83 g.CO2.m-2 d-1 y 2,06 ? 5,20 mg.N2O.m-2 d-1. Por ?ltimo los flux promedios obtenidos para el punto P3A fueron 1,80 ? 6,89 g.CH4.m-2 d-1; 1,40 ? 8,40 g.CO2.m-2 d-1 y -1,24 ? 6,43 mg.N2O.m-2 d-1. Las pruebas estad?sticas indicaron que los flux de los gases de efecto invernadero estudiados presentaron una variaci?n espacial significativa entre los puntos muestreados. CH4 present? variaci?n entre los puntos P1, P2 y P3 (p<0.001 Mann-Whitney) y evidenci? similitudes entre los puntos P3A-P3 y P3A-P2 (p>0.05 Mann-Whitney). Para CO2 se evidenci? similitud para los flux obtenidos en los cuatro puntos (p>0.05 Mann-Whitney). Por su parte, para el ?xido nitroso tambi?n se present? un comportamiento similar en los cuatro puntos sin variaci?n significativa (p>0.05 Mann-Whitney). Con respecto a las relaciones entre los par?metros de calidad de agua, sedimentos y los flux de gases de efecto invernadero, se determin? que los par?metros con mayor influencia sobre la producci?n y consumo de CH4 CO2 y N2O fueron hierro f?rrico (Fe+3) Coeficiente Spearman = -73%), nitratos (NO3) (Coeficiente Spearman = -65%) y los nitritos (NO2) en sedimentos Coeficiente Spearman = 86%), respectivamente. Los resultados obtenidos en este estudio evidenciaron que la intervenci?n antr?pica contribuye al estado eutr?fico del ecosistema y este a su vez influencia la din?mica de producci?n y consumo de GEI favoreciendo el incremento en la generaci?n de estos, demandando medidas de manejo y control que permitan mitigar el impacto frente al cambio clim?tico

The effect of hook size on the catch rate and size of the Nile perch Lates niloticus (Linne) fishery in the Napoleon Gulf, Lake Victoria, Uganda

This study was undertaken in Napoleon gulf, Lake Victoria Uganda from July – December 2009. It was conducted in four landing sites; Bukaya (0.41103N, 33.19133E), Bugungu (0.40216N, 33.2028E), Busana (0.39062N, 33.25228E) and Kikondo (0.3995N, 33.21848E) all from Buikwe district (Formerly part of Mukono district). The main aim was to determine the effect of both hook size and bait type on the catch rate (mean weight) and size composition of Nile perch (Lates niloticus) (LINNE) fishery in the Napoleon Gulf, Lake Victoria. The main hook sizes investigated during the experiment were 7, 8, 9, 10, 11 and 12 that were dominantly used in harvesting Nile perch in Napoleon Gulf, Lake Victoria. In this study length, weight and bait type data were collected on site from each boat at that particular fishing spot; since most fishermen in the Napoleon Gulf could sell their fish immediately the catch is caught there and then. The results indicated a total of 873 Nile perch fish samples collected during the study. Statistical tests, descriptive statistics, regression and correlation were all carried out using the Statistical Package for the Social Sciences (SPSS) in addition to Microsoft excel. The bait types in the Gulf ranged from 5-10 cm Total length (TL) haplochromine, 24.5-27 cm TL Mormyrus kannume and 9-24 cm TL Clarias species. The bait types had a significant effect on the catch rate and also on the size composition the fish harvested measured as Total length (ANCOVA F=8.231; P<0.05) despite the fact that bait type had no influence on mean weight of fish captured (ANCOVA F=2.898; P>0.05). Hook sizes used by the fishers had a significant effect on the both the size (TL) composition (ANCOVA F=3.847; P<0.05) and the mean weight (ANCOVA F=4.599; P<0.005) of the Nile perch captured. Investigations indicated hook sizes seven (7) and eight (8) were the ones that harvested the Nile perch above the slot size of 50 cm total length. In general hook sizes indicated to be the main drive in the harvesting of the Nile perch though bait type also contributed toward that. Generally there is need for management to put a law in place on the minimum hook size to be used on the harvesting of the Nile perch and also monitored by the Fisheries Management as a regulatory measure. In addition to that aquaculture should be encouraged to farm the fish for bait at a higher scale in the region in order to avoid depleting the wild stocks already in danger of extinction. Through this kind of venture, both biodiversity conservation and environmental sustainability will be observed in the Lake Victoria basin.

Microfluidic platforms for the characterization of in meso membrane protein crystallization

Membrane proteins, which reside in the membranes of cells, play a critical role in many important biological processes including cellular signaling, immune response, and material and energy transduction. Because of their key role in maintaining the environment within cells and facilitating intercellular interactions, understanding the function of these proteins is of tremendous medical and biochemical significance. Indeed, the malfunction of membrane proteins has been linked to numerous diseases including diabetes, cirrhosis of the liver, cystic fibrosis, cancer, Alzheimer's disease, hypertension, epilepsy, cataracts, tubulopathy, leukodystrophy, Leigh syndrome, anemia, sensorineural deafness, and hypertrophic cardiomyopathy.1-3 However, the structure of many of these proteins and the changes in their structure that lead to disease-related malfunctions are not well understood. Additionally, at least 60% of the pharmaceuticals currently available are thought to target membrane proteins, despite the fact that their exact mode of operation is not known.4-6 Developing a detailed understanding of the function of a protein is achieved by coupling biochemical experiments with knowledge of the structure of the protein. Currently the most common method for obtaining three-dimensional structure information is X-ray crystallography. However, no a priori methods are currently available to predict crystallization conditions for a given protein.7-14 This limitation is currently overcome by screening a large number of possible combinations of precipitants, buffer, salt, and pH conditions to identify conditions that are conducive to crystal nucleation and growth.7,9,11,15-24 Unfortunately, these screening efforts are often limited by difficulties associated with quantity and purity of available protein samples. While the two most significant bottlenecks for protein structure determination in general are the (i) obtaining sufficient quantities of high quality protein samples and (ii) growing high quality protein crystals that are suitable for X-ray structure determination,7,20,21,23,25-47 membrane proteins present additional challenges. For crystallization it is necessary to extract the membrane proteins from the cellular membrane. However, this process often leads to denaturation. In fact, membrane proteins have proven to be so difficult to crystallize that of the more than 66,000 structures deposited in the Protein Data Bank,48 less than 1% are for membrane proteins, with even fewer present at high resolution (< 2Å)4,6,49 and only a handful are human membrane proteins.49 A variety of strategies including detergent solubilization50-53 and the use of artificial membrane-like environments have been developed to circumvent this challenge.43,53-55 In recent years, the use of a lipidic mesophase as a medium for crystallizing membrane proteins has been demonstrated to increase success for a wide range of membrane proteins, including human receptor proteins.54,56-62 This in meso method for membrane protein crystallization, however, is still by no means routine due to challenges related to sample preparation at sub-microliter volumes and to crystal harvesting and X-ray data collection. This dissertation presents various aspects of the development of a microfluidic platform to enable high throughput in meso membrane protein crystallization at a level beyond the capabilities of current technologies. Microfluidic platforms for protein crystallization and other lab-on-a-chip applications have been well demonstrated.9,63-66 These integrated chips provide fine control over transport phenomena and the ability to perform high throughput analyses via highly integrated fluid networks. However, the development of microfluidic platforms for in meso protein crystallization required the development of strategies to cope with extremely viscous and non-Newtonian fluids. A theoretical treatment of highly viscous fluids in microfluidic devices is presented in Chapter 3, followed by the application of these strategies for the development of a microfluidic mixer capable of preparing a mesophase sample for in meso crystallization at a scale of less than 20 nL in Chapter 4. This approach was validated with the successful on chip in meso crystallization of the membrane protein bacteriorhodopsin. In summary, this is the first report of a microfluidic platform capable of performing in meso crystallization on-chip, representing a 1000x reduction in the scale at which mesophase trials can be prepared. Once protein crystals have formed, they are typically harvested from the droplet they were grown in and mounted for crystallographic analysis. Despite the high throughput automation present in nearly all other aspects of protein structure determination, the harvesting and mounting of crystals is still largely a manual process. Furthermore, during mounting the fragile protein crystals can potentially be damaged, both from physical and environmental shock. To circumvent these challenges an X-ray transparent microfluidic device architecture was developed to couple the benefits of scale, integration, and precise fluid control with the ability to perform in situ X-ray analysis (Chapter 5). This approach was validated successfully by crystallization and subsequent on-chip analysis of the soluble proteins lysozyme, thaumatin, and ribonuclease A and will be extended to microfluidic platforms for in meso membrane protein crystallization. The ability to perform in situ X-ray analysis was shown to provide extremely high quality diffraction data, in part as a result of not being affected by damage due to physical handling of the crystals. As part of the work described in this thesis, a variety of data collection strategies for in situ data analysis were also tested, including merging of small slices of data from a large number of crystals grown on a single chip, to allow for diffraction analysis at biologically relevant temperatures. While such strategies have been applied previously,57,59,61,67 they are potentially challenging when applied via traditional methods due to the need to grow and then mount a large number of crystals with minimal crystal-to-crystal variability. The integrated nature of microfluidic platforms easily enables the generation of a large number of reproducible crystallization trials. This, coupled with in situ analysis capabilities has the potential of being able to acquire high resolution structural data of proteins at biologically relevant conditions for which only small crystals, or crystals which are adversely affected by standard cryocooling techniques, could be obtained (Chapters 5 and 6). While the main focus of protein crystallography is to obtain three-dimensional protein structures, the results of typical experiments provide only a static picture of the protein. The use of polychromatic or Laue X-ray diffraction methods enables the collection of time resolved structural information. These experiments are very sensitive to crystal quality, however, and often suffer from severe radiation damage due to the intense polychromatic X-ray beams. Here, as before, the ability to perform in situ X-ray analysis on many small protein crystals within a microfluidic crystallization platform has the potential to overcome these challenges. An automated method for collecting a "single-shot" of data from a large number of crystals was developed in collaboration with the BioCARS team at the Advanced Photon Source at Argonne National Laboratory (Chapter 6). The work described in this thesis shows that, even more so than for traditional structure determination efforts, the ability to grow and analyze a large number of high quality crystals is critical to enable time resolved structural studies of novel proteins. In addition to enabling X-ray crystallography experiments, the development of X-ray transparent microfluidic platforms also has tremendous potential to answer other scientific questions, such as unraveling the mechanism of in meso crystallization. For instance, the lipidic mesophases utilized during in meso membrane protein crystallization can be characterized by small angle X-ray diffraction analysis. Coupling in situ analysis with microfluidic platforms capable of preparing these difficult mesophase samples at very small volumes has tremendous potential to enable the high throughput analysis of these systems on a scale that is not reasonably achievable using conventional sample preparation strategies (Chapter 7). In collaboration with the LS-CAT team at the Advanced Photon Source, an experimental station for small angle X-ray analysis coupled with the high quality visualization capabilities needed to target specific microfluidic samples on a highly integrated chip is under development. Characterizing the phase behavior of these mesophase systems and the effects of various additives present in crystallization trials is key for developing an understanding of how in meso crystallization occurs. A long term goal of these studies is to enable the rational design of in meso crystallization experiments so as to avoid or limit the need for high throughput screening efforts. In summary, this thesis describes the development of microfluidic platforms for protein crystallization with in situ analysis capabilities. Coupling the ability to perform in situ analysis with the small scale, fine control, and the high throughput nature of microfluidic platforms has tremendous potential to enable a new generation of crystallographic studies and facilitate the structure determination of important biological targets. The development of platforms for in meso membrane protein crystallization is particularly significant because they enable the preparation of highly viscous mixtures at a previously unachievable scale. Work in these areas is ongoing and has tremendous potential to improve not only current the methods of protein crystallization and crystallography, but also to enhance our knowledge of the structure and function of proteins which could have a significant scientific and medical impact on society as a whole. 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Evaluación de los bulbos de humedecimiento con fines de generar datos preliminares para el diseño de sistemas de riego por goteo.

Los sistemas de riego por goteo normalmente mojan sólo una porción del área de suelo a lo cual se le llama: porcentaje de área humedecida. Este valor depende del volumen de agua aplicado, espaciamientos de puntos de emisión y tipo de suelo que se está regando. El porcentaje de área humedecida tiene influencia sobre los parámetros de diseño de un sistema de riego por goteo, tal porcentaje no se ha establecido para cultivos de espaciamientos mayores de 1.8m. Con el estado actual de conocimiento, un objetivo razonable como lo mencionan varios autores (11,13), es por lo menos mojar entre un tercio y un medio del área total correspondiente a una planta. Se utilizó un diseño estadístico completamente al azar en arreglo factorial 3x3 con repeticiones. El total de tratamientos fue de 9, constituidos por la combinación del volumen de agua aplicado (12 lts., 24 lts., y 48 lts.), y la textura (Arenoso- franco, Franco-Arcilloso y Franco). La prueba consistió en aplicar un caudal de 4 LPH en tres tipos (3h, 6h, y 12hh), en las texturas de estudio, que se evaluaron en cajas de madera, después de cada tiempo de aplicación se midió el diámetro del bulbo humedecido a intervalos de 5 cm de profundidad, hasta cubrir el bulbo humedecido. En este sentido, el presente trabajo tiene por objetivo la determinación del número de goteros por planta y volumen de agua aplicado que humedezca del 33% al 50% del área total del sistema de raíces. La determinación de tal porcentaje de humedecimiento contribuirá al desarrollo de la agricultura bajo riego en El Salvador. Entre los resultados obtenidos en este experimento se pueden mencionar la relación que existe entre el diámetro del bulbo humedecido (DC) y el volumen de agua aplicado (V), tal relación puede ser expresada matemáticamente mediante una ecuación de tipo exponencial para cada uno de los suelos analizados. Las ecuaciones que representan la relacion entre Dc y V, son: Arena-franca:Dc = 26.9 (V) °.27 Franca-arcillosa: Dc = 76.4 (V) °.27 Franca:Dc = 29.3 (V) °.38 En relación a lo anterior se concluye lo siguiente: 1.Que el diámetro del bulbo humedecido está íntimamente ligado con el tipo de suelo y el volumen de agua aplicado. 2.Una vez conocido el diámetro de bulbo húmedo y suponiendo un número determinado de goteros se puede estimar el porcentaje de área humedecido. 3.Los diámetros leídos en el campo para determinado suelo están influenciados por el contenido de humedad al momento de realizar la prueba.

Relationship between hyperacute blood pressure and outcome after ischemic stroke: data from the VISTA Collaboration

Background and Purpose—High blood pressure (BP) is associated independently with poor outcome after acute ischemic stroke, although in most analyses “baseline” BP was measured 24 hours or more postictus, and not during the hyperacute period. Methods—Analyses included 1722 patients in hyperacute trials (recruitment 8 hours) from the Virtual Stroke International Stroke Trial Archive (VISTA) Collaboration. Data on BP at enrolment and after 1, 2, 16, 24, 48, and 72 hours, neurological impairment at 7 days (NIHSS), and functional outcome at 90 days (modified Rankin scale) were assessed using logistic regression models, adjusted for confounding variables; results are for 10-mm Hg change in BP. Results—Mean time to enrolment was 3.7 hours (range 1.0 to 7.9). High systolic BP (SBP) was significantly associated with increased neurological impairment (odds ratio, OR 1.06, 95% confidence interval, 95% CI 1.01 to 1.12), and poor functional outcome; odds ratios for both increased with later BP measurements made at up to 24 hours poststroke. Smaller (versus larger) declines in SBP over the first 24 hours were significantly associated with poor NIHSS scores (OR 1.16, 95% CI 1.05 to 1.27) and functional outcome (OR 1.23, 95% CI 1.13 to 1.34). A large variability in SBP was also associated with poor functional outcome. Conclusions—High SBP and large variability in SBP in the hyperacute stages of ischemic stroke are associated with increased neurological impairment and poor functional outcome, as are small falls in SBP over the first 24 hours.