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Prediction of sudden cardiac death (SCD) after acute coronary syndromes (ACS) remains a challenge. Although electrophysiology measures obtained by 3-D vectorcardiography (VCG) shortly after ACS may be useful predictors of SCD, they have not been adopted into clinical practice. The main objective of our study was to assess whether the VCG-derived QRS-T area angle (between area vectors) and the QRS-T angle (between maximum vectors) have additional value beyond standard risk factors in predicting SCD after ACS.We studied 643 consecutive ACS patients for whom data on VCG and echocardiography during the index hospitalization were available. Seventy-seven patients (12%) died, 37 (6%) from SCD and 21 (3%) from other cardiac causes during the 30-month follow-up. After adjusting for 9 standard risk factors (age, sex, diabetes, previous stroke, left ventricular ejection fraction; and estimated glomerular filtration rate, heart rate, systolic blood pressure100mmHg, and Killip class1 on admission), QRS-T area angle and QRS-T angle were shown to have independent predictive value for both SCD and all cardiac deaths. Reclassification analysis showed that both measures had additional predictive value beyond the 9 standard risk factors. For SCD, net reclassification improvements for QRS-T area angle and QRS-T angle were 46% and 45% and relative integrated discriminative improvements were 16% and 13% (vs the average~11% of the 9 standard risk factors).The VCG-derived QRS-T area angle and QRS-T angle improved prediction of SCD after ACS beyond standard risk factors. Further evaluation of their clinical utility and cost-effectiveness is therefore warranted.

The effect of pipe fittings (mainly T-pieces) on particle accumulation in drinking water distribution networks were shown in this work. The online measurements of flow and turbidity for cast iron, polyethylene and polyvinyl chloride pipe sections were linked with analysis of pipe geometry. Up to 0.29 kg of the total amount mobilized in T-pieces ranging from DN 100/100–DN 250/250. The accumulated amount of particles in fittings was defined as J and introduced into the existing turbidity model PODDS (prediction of discoloration in distribution systems) proposed by Boxall et al. (2001) which describes the erosion of particles leading to discoloration events in drinking water network viz sections of straight pipes. However, this work does not interpret mobilization of particles in pipe fittings which have been considered in this article. T-pieces were the object of this study and depending of the diameter or daily flow velocity, the coefficient J varied from 1.16 to 8.02. The study showed that pipe fittings act as catchment areas for particle accumulation in drinking water networks.

The addition of labile organic carbon (LOC) to enhance the biodegradation rate of dissolved organic carbon (DOC) in biological columns was studied. Acetate standard solution (NaAc) and Luria Bertrani (LB) medium were used as LOC as biostimulants in glass column system used for measurements of biodegradable dissolved organic carbon (BDOC). The addition of LOC related with the increase of total DOC in sample. The concentration of BDOC increased up to 7 and 5 times and was utilized after 24 min. contact time. The biodegradation rate constant was increased at least 26 times during adaptation-biostimulation period. There was a strong positive correlation between the biodegradation rate constant and the concentration of BDOC. Biostimulation period ranged from 24 to 53 h for NaAc biostimulant and from 20 to 168 h for LB. The study has shown that LOC could be used as stimulator to enhance the biodegradation rate of DOC during biofiltration.

Aims Cardiac resynchronization therapy (CRT) may cause changes in ventricular repolarization (VR), particularly in the initial phase of treatment. This study investigated the effect of CRT cessation and re-initiation on parameters of VR duration and heterogeneity at different paced heart rates. Methods Cardiac resynchronization therapy was inactivated for 2 weeks in 16 treatment responders to CRT. QT and JT intervals were measured on the surface electrocardiogram at 60, 70, and 80 bpm (randomized order) and vectorcardiography (VCG) was performed with CRT ‘on’ (day 0), ‘off’ (day 0, 1, 7, and 14) and after CRT re-initiation (day 14, 15, 16, and 21). On day 0 (‘on’) and 14 (‘off’) echocardiography, the 6 min walking distance and brain natriuretic peptide were assessed. Results The QT interval at baseline (CRT ‘on’), measured at 60, 70, and 80 bpm, was 482 ± 31, 468 ± 37, and 457 ± 39 ms, respectively, and decreased by 5, 5, and 6% during the first week following CRT cessation (all P < 0.05). Immediately after re-initiation on day 14, it increased again by 20 ± 18 (4%; P < 0.05), 34 ± 39 (8%; P < 0.01), and 16 ± 38 ms (4%, ns) followed by a gradual decrease towards previous ‘off’ levels. Similar changes were observed for the JT interval. Ventricular repolarization duration was significantly shortened by increasing the paced heart rate from 60 to 70 and 80 bpm. Vectorcardiography parameters reflecting VR gradients (ST-vector magnitude, Tarea, and Tavplan) increased significantly (by 31, 45, and 71%) after CRT cessation. A similar but non-significant pattern was observed after CRT re-initiation. Conclusion The increase in repolarization duration and gradients observed after CRT initiation suggests a transient state of VR instability that can be attenuated by programming of higher paced heart rates during the initial phase of treatment.

The ventricular repolarization (VR) response to short-lasting coronary occlusion has been characterized by 3-dimensional vectorcardiography (VCG) in humans; the T vector loop becomes distorted and more circular. The purpose of this study was to relate these changes to the size of the myocardium at risk (MAR) and its location.Continuous VCG was applied during transient coronary occlusion in 35 elective angioplasty patients, and the size of the MAR was estimated by single-photon emission computed tomography. Three VR aspects were assessed at baseline vs maximum ischemia: the ST segment, the T vector angles, and the T vector loop morphology.The T loop morphology changes were significantly associated with MAR size, but also dependent of its location. In contrast, the early phase of VR reflected by the ST segment responded to acute ischemia in relation to the MAR size independent of location.The VR changes were related both to the size and the location of the MAR and most pronounced during occlusion of the left anterior descending artery.

Prolonged exercise can induce cardiac fatigue, which is characterized by biomarker release and impaired myocardial function. The impact on ventricular electrophysiology is largely unknown.The objective of this study was to examine changes in ventricular repolarization after a 30-km cross-country race in runners agedor=55 years.Fifteen healthy participants (62 +/- 5 years) were assessed using biomarkers (N-terminal pro-brain natriuretic peptide [NT-proBNP], troponin T [TnT]), tissue Doppler echocardiography, and vectorcardiography at baseline, within 1 hour postrace and on days 1 and 6 postrace.During the race, NT-proBNP increased from 42 ng/L (interquartile range 25-117) to 187 ng/L (113-464), and TnT increased from undetectable levels to 0.03 microg/L (0.015-0.05). Global strain (19.1% +/- 2.2%) decreased on day 1 (17.2% +/- 1.8%) and day 6 (17.9% +/- 1.5%; P.01). QT(c) increased from 431 +/- 15 ms prerace to 445 +/- 22 ms postrace and 445 +/- 15 ms on day 1 (P.05), mainly because of an increased T(peak-end) interval (prerace 108 +/- 13 ms, postrace 127 +/- 43 ms, day 1 127 +/- 43 ms; P.05). Postrace, T(area) (baseline 75 +/- 26 microVs) peaked on day 1 (105 +/- 42 microVs) and remained high on day 6 (89 +/- 37 microVs; P.05). Runners with higher baseline NT-proBNP developed greater impairment of myocardial velocities (rho = -0.68 to -0.54; P.05) and a larger increase in T(area) (rho = 0.73; P.01).Cardiac fatigue induced by prolonged exertion is associated with sustained abnormalities in ventricular repolarization. Runners with higher baseline NT-proBNP are especially liable to such alterations of cardiac function.

Background Right ventricular apical (RVA) pacing induces electrophysiological and structural remodeling. Cardiac memory (CM) evolves during the course of pacing and is readily apparent on electrocardiography (ECG) or vectorcardiography (VCG) when normal ventricular activation resumes. Objective This study sought to assess ventricular repolarization (VR) changes during pacing and intermittent normal ventricular conduction by ECG and VCG and to determine the temporal and conformational evolution of CM. Methods Twenty sick sinus patients received a dual-chamber rate-adaptive (DDD-R) pacemaker and were paced from the RVA endocardium. The pacemakers were programmed to a short AV delay to maximize ventricular preexcitation. The ECG and VCG were recorded before and 1 day after implantation, and then daily for the first week (n = 6) or weekly for 5 to 8 weeks (n = 14), with the pacemakers temporarily programmed to AAI (normal ventricular activation). Results The first parameters to change were T-vector amplitude, T area , and T peak -T end (T p-e ), which decreased within 1 day after initiating pacing. CM became apparent between day 1 and day 3, was fully established after 1 week, and then remained stable. Signs of increased VR heterogeneity were observed as the T loop became more circular (decreased T egenv ) and distorted (increased T avplan ), which have previously been observed in conditions with increased risk for arrhythmias. Over weeks, VR duration was prolonged (increased QTc). In contrast, during ventricular pacing, a gradual shortening of the repolarization time was observed, suggesting a stabilizing adaptive process. Conclusion In sick sinus syndrome patients in whom ventricular pacing is indicated, switching between normal AV conduction and ventricular pacing should be minimized to avoid periods of repolarization instability.

The effect of phosphorus addition on survival of Escherichia coli in an experimental drinking water distribution system was investigated. Higher phosphorus concentrations prolonged the survival of culturable E. coli in water and biofilms. Although phosphorus addition did not affect viable but not culturable (VBNC) E. coli in biofilms, these structures could act as a reservoir of VBNC forms of E. coli in drinking water distribution systems.

Effect of microbially available phosphorus (MAP) on biofilm development in drinking water systems was investigated at the pilot-scale experiments over 3 years. Completely mixed biofilm reactors Propella® (water detention time 24 h, flow rate 0.25 m s−1, PVC pipe coupons) were used as water distribution network models. Four experimental runs were carried out with water containing different levels of phosphorus which was limiting nutrient for bacterial growth. Positive correlation between MAP in the inlet water and heterotrophic plate count (correlation coefficient 0.95) in biofilm, as well as for the total bacteria number (correlation coefficient 0.71), was observed. However, our experiments showed that removal of phosphorus down to very low levels (below detection limits of chemical method and MAP

Chemical precipitation in combination with biological treatment is a commonly used method for removal of turbidity and dissolved organic carbon (DOC) from drinking water. DOC is largely removed during biological treatment, which includes ozonation and filtration through a biologically active carbon (BAC) filter. Ozone converts humic substances into a biologically labile form that is mineralised by bacteria living in the following BAC filter. This study shows that this approach is often not efficient for removal of DOC from waters with a high amount of humic substances. During chemical treatment, the microbiologically available phosphorus is very efficiently removed, which results in shortages of phosphorus needed for bacteria to mineralise carbon in BAC filters. To enhance removal of DOC by biological treatment, addition of phosphorus prior to the BAC filters should be considered.

Membranes are widely used for the treatment of various solutions. However, membrane fouling remains the limiting factor for their usage, setting biofouling as the most severe type of it. Therefore, the production of biologically stable water prior to membranes is important. Since lack of phosphorus may hinder the growth of microorganisms, the aim of this research is to evaluate the effect of microbially available phosphorus (MAP) removal via affordable water pre-treatment methods (adsorption, biofiltration, electrocoagulation) on bacterial growth. Four cylindrical reactors were installed at an artificially recharged groundwater station. Further temperature influence and carbon limitation were tested for biofiltration technology. The amount of MAP and total cell count was measured by flow cytometry. The results showed that at lower temperatures electrocoagulation performed the best, resulting in complete MAP removal (detection limit 6.27x10-3μg P l-1). Sorbent demonstrated MAP removal of 70-90%. Biomass did not have any noteworthy results at +8°C, however, at +19°C MAP removal of around 80% was achieved. Main conclusions obtained within this study are: (i) tested technologies effectively eliminate MAP levels; (ii) temperature has a significant effect on MAP removal in a bioreactor, (iii) multi-barrier approach might be necessary for better P limitation that might prolong operating time of a membrane.

The Republic of Latvia has promulgated a number of laws that govern the national response to emergencies in water and wastewater.

The consumption of lactose in acid cheese whey anaerobic fermentation process under fed-batch conditions was studied. During fermentation for 100 hours the biogas production (CO2 and CH4) was analyzed online. Among the standard analyses FT-IR spectroscopy was used to follow the consumption of lactose by bacteria. The absorption bands at 990, 894 and 787 cm-1 in the 2nd derivative spectra were shown to be characteristic for lactose and were used to follow the lactose conversion. It was shown that acid cheese whey lactose was converted by bacteria in first 7 hours. In the spectra of 17, 18 and 95 hour fermentation samples lactose was not identified and these results correlated with the HPLC data.

The addition of labile organic carbon (LOC) to enhance the biodegradation rate of dissolved organic carbon (DOC) in biological columns was studied. Acetate standard solution (NaAc) and LB (Luria Bertrani) medium were used as LOC as biostimulants in glass column system used for measurements of biodegradable dissolved organic carbon (BDOC). The addition of LOC related with the increase of total DOC in sample. The concentration of BDOC increased up to 7 and 5 times and was utilized after 24 min. contact time. The biodegradation rate constant was increased at least 8 times during adaptation-biostimulation period. There was a strong positive correlation between the biodegradation rate constant and the concentration of BDOC. Biostimulation period ranged from 24 to 53 h for NaAc biostimulant and from 20 to 168 h for LB. The study has shown that LOC could be used as stimulator to enhance the biodegradation rate of DOC during biofiltration.

The present study was designed to describe the turbidity curve obtained during planned unidirectional flushing in drinking water distribution system of a diameter 100-300 mm. The online measurements of flow and turbidity for cast iron (n=16), polyethylene (PE, n=7) and polyvinylchloride (PVC, n=4) pipe sections and calculations of hydraulic values indicated that the turbidity curve peaks appeared at the locations of bends, tees, narrow parts of the pipes etc viz. where increased hydraulic drops take place. The application of on-line measurements during the wash-out of loose deposits in both cases from one and two hydrants simultaneously, the calculations of average velocity (0.72 m/s, n=22) and shear stress (2.05 N/ m 2 , n=29) on pipe walls showed that the loose deposits in the pipes move according to plug-flow principle in a turbulent regime. The granulometric analysis of loose deposits showed that the average diameter ranged from

The tracer tests were performed using two approaches in the drinking water distribution network (1374 km) of Riga city, Latvia with the goal to verify and validate a hydraulic model build up in Epanet 2.0. The water is supplied for 700 000 inhabitants with average daily water demand of 1500 l/s from six different water sources. The each water source has a different electric conductivity (EC) value with the lowest numbers for deep groundwater 272±25 µS/cm (25 O C) and the highest for surface and artificially recharged groundwater 468±100 and 784±18 µS/cm, respectively. The significant difference for EC in sources was used as a natural tracer. The first measurement approach is based on field works during shut-down or start-up of WTP due to monthly working regime or yearly drainage of clear water tanks at stations located in the north-east of city. In total more than 20 locations in distribution network were used for measurements of EC from hydrants and/or at taps in buildings applying online conductivity meters 3400sc™ (Dr. Bruno Lange GmbH&Co, Germany) and condu::lyser™ (s::can Mestechnik GmbH, Austria) in predictable time interval. The second approach of tracer measurements was based on EC measurements in network within close distance to track minor changes of EC due to production/consumption ratio. The hydraulic model of Riga city was validated in 8 nodes with the maximum age of 25:40 hours, while the distal nodes in model accounts for 60 hours. Results showed that in order to measure correct changes of trace element it is necessary to do it very close to transient pipes with high flow. The measurements of tracer near reservoirs in network are unpredictable due to proper mixing of water. The approach of measurements with two online instruments in close distance (up to 5 km) to track minor changes of EC can be useful for validation of hydraulic models. However, the statistical analysis (z-test) of this method showed significant difference between mean values of measurements which can be explained with too many uncertainties (cross-connections of parallel lines, loops) for water mixing in city with population of 700 000 inhabitants.

In the present study the time of adaptation of fixed biomass for biodegradation of natural organic matter was investigated. The experiments were done in columns that are usually used for rapid determination of biodegradable dissolved organic carbon (BDOC). The biomass was adapted to samples with different concentrations of organic substances before measurements by pumping water to be investigated through the columns for several days. The time of adaptation was dependent on the initial concentration of the organic matter in the water sample. The adaptation time increased from 6 to 24 h with increase of concentration of acetate solution from 2 to 10 mg/l, thus adaptation rate decreased simultaneously from 0.28 to 0.11 min(-1). In natural water samples with the initial concentration in the range from 4.61-10.82 mg/l of dissolved organic carbon (DOC) the maximal adaptation time was less than 24 h. During the adaptation period the increase in reproducibility and decrease in the standard deviation was observed. The study showed that adaptation of column to the different concentration of organic matter in water sample is necessary in order to decrease the bias in BDOC measurements when using columns tests.

Reliable cardiovascular (CV) risk assessment by a noninvasive tool would be of great value for CV event prevention. The present study consists of 187 coronary artery disease patients with 8 years of follow-up. Eight vectorcardiographic parameters characterizing different aspects of ventricular repolarization were analyzed at baseline: (1) the ST-segment (ST-VM), (2) the T vector angles (QRS-T angle, Televation, and Tazimuth), (3) the T vector loop morphology (Tavplan and Teigenvalue), and (4) Tarea and Tpeak-end. Cardiovascular death, myocardial infarction (MI), and repeated revascularization were traced via national registries. There were 16 CV deaths and 19 MIs; 89 patients remained free from CV events and revascularization. Ventricular repolarization parameters independently predicted CV death (widened QRS-T angle) and new MI (increased Tavplan) during follow-up. CV mortality was associated with increased divergence between depolarization and repolarization waves (widened QRS-T angle). Increased Tavplan, presumably reflecting heterogeneous repolarization, predicted future MI, which is a novel finding.

Comprehensive studies of radiation effects on the optical and dielectric properties of PLZT X/65/35 ceramics have been made. The samples have been exposed to gamma-electron and reactor neutron irradiation.

Baktēriju transports un izplatīšanas ūdens padeves sistēmās ir jākontrolē. Simulācijas rīki ir nepieciešami, lai varētu veikt efektīvu baktēriju koncentrācijas monitoringu. Daudzi autori pētīja baktēriju augšanu ūdensvados. Tika mēģināts izstrādāt modeli baktēriju augšanas simulācijai ūdensvados. Tika pievērsta uzmanība arī faktoriem, kas ietekmē baktēriju augšanu. Diemžēl, ir dažādas problēmas, kas apgrūtina modeļa izveidošanu. Piemēram, baktēriju augšanu ietekmē daudzi faktori, tātad jāizvēlas svarīgākie, jo pilnīgi visus faktorus ņemt vērā nav iespējams. Iepriekšējos pētījumos tika izskatīts modelis, ko piedāvāja Zhang et al (2004). Tika paradīts, ka modelis var būt iekļauts Epanet-MSX programmatūra un rezultāti, kas bija iegūti ar EPANET-MSX programmatūras palīdzību bija salīdzināti ar rezultātiem no validētas Fortran programmas. Salīdzinājums paradīja, ka rezultāti ir stipri līdzīgi. Šī pētījuma ietvaros tika pārbaudīta EPANET-MSX modeļa pielietojamība nelielam ūdensvadu tīklam. Rezultāti, kas tika iegūti ar EPANET-MSX programmas palīdzību tika salīdzināti ar rezultātiem, ko ieguva Zhang et al (2004). Tika paradīts, ka rezultāti ir salīdzināmi, tātad var cerēt, ka EPANET-MSX modeli varēs izmantot baktēriju izplatīšanas modelēšanai arī ūdensvadu tīklos.

Bioloģiski degradējamā organiskā oglekļa noteikšana ūdenī: suspendētas un adsorbētas biomasas metožu salīdzināšana. Rakstā salīdzinātas trīs metodes bioloģiski degradējama organiskā oglekļa (BDOC) noteikšanai. Mēs novērtējām metožu atkārtojamību un reproducējamību. Rezultātu salīdzināšanai un datu statistiskai apstrādei, pārbaudīti trīs veidu ūdeņi (dzeramais ūdens, upes ūdens un sintētiskais paraugs) ar trīs dažādām metodēm un divām šo metožu modifikācijām, izmatojot baktēriju suspensiju, fiksēto biomasu pudeļu testā un fiksēto biomasu divu kolonu sistēmā. Pētījuma rezultāti parāda, ka BDOC noteikšanas metožu precizitāte ir līdzīga (4-26%), atšķirībā no tā, ka BDOC variē (no 14% līdz 19% no izšķīduša organiskā oglekļa (DOC) upes ūdenim un no 45% līdz 59% no DOC dzeramajam ūdenim). Turpmākajiem pētījumiem rekomendējam divu kolonu metodi.

Risinājums baktēriju izplatīšanās problēmai ūdensvados tika meklēts vairākos pētījumos. Dažādi autori mēģināja izveidot modeļus, kas dotu iespēju simulēt baktēriju augšanu dzeramā ūdensvada tīklos un noteikt kādi faktori ietekmē baktēriju attīstību. Baktēriju augšanu ietekmē daudzi faktori, kas apgrūtina aprēķinu un ietvert tos visus modelī nav iespējams. Tomēr eksistē modeļi, kas no vienas puses ņem vērā vissvarīgākos faktorus, no kuriem ir atkarīga baktēriju izplatīšanās, un no otrās puses ir pietiekoši kompakti, lai viņus varētu pielietot vidēja līmeņa datoriem, kas ir pieejami laboratorijās. Tomēr jāveic pētījumi ar mērķi salīdzināt dažādus modeļus un pārbaudīt rezultātu atkārtojamību gadījumā, ja rezultāti tiek iegūti ar dažādām modelēšanas programmām. Šajā pētījumā tika salīdzināti rezultāti, kas iegūti ar Fortran IMSL bibliotēku un Epanet-MSX programmas paketi. Zhang et al (2004) piedāvāja matemātisko modeli, kas apraksta baktēriju augšanu ūdensvados. Šajā pētījumā modeļa vienādojumi tika atrisināti taisnas caurules gadījumam, izmantojot Fortran IMSL bibliotēku. Tie paši vienādojumi, izņemot dispersijas locekli tika ievadīti Epanet-MSX vidē. Rezultāti tika salīdzināti savā starpā. Tika atrasts, ka rezultāti, kas bija iegūti ar Fortran IMSL palīdzību, labi sakrīt ar rezultātiem no Epanet-MSX programmas. Var secināt, ka dispersijas loceklis vienādojumos var būt ne īpaši nozīmīgs atsevišķos gadījumos.

Epidemiological studies show that left ventricular hypertrophy (LVH) and hypertension (HT) in coronary artery disease increases the risk for cardiovascular events including sudden cardiac death (SCD). According to experimental studies, myocardial hypertrophy is associated both with altered electrophysiological properties (including prolonged repolarization) and increased vulnerability to ischemia. However, human data to support a repolarization-related mechanism for the increased SCD risk has not been provided. We therefore studied 187 patients undergoing three-dimensional vectorcardiographic monitoring during coronary angioplasty. Eight parameters reflecting different aspects of ventricular repolarization were used: 1) the ST segment (ST-VM and STC-VM), 2) the T vector (QRS-T angle, Televation, and Tazimuth), and 3) the T vector loop (Tavplan, Teigenv, and Tarea). Data collection was performed at rest and at the time of maximum ischemia during coronary occlusion. The patients were divided into three groups: 33 patients with ECG signs of LVH (18 with HT), 54 with HT but without LVH signs, and 100 patients with neither. Coronary artery disease patients with LVH not only had the most abnormal baseline repolarization (as expected) but also a significantly more pronounced repolarization response during coronary occlusion, whereas HT patients had mean parameter values between LVH patients and those without neither HT nor LVH signs. Because there is a relation between increased SCD risk and repolarization disturbances in various clinical settings, the results of the present study are in agreement with animal data and epidemiological observations, although other factors than disturbed repolarization might be of importance.

Pētījums par fosfora ietekmi baktēriju attīstību dzeramā ūdens apgādes sistēmā.

Darbā aprakstīta baktēriju attīstības modelēšana ūdensvada caurulē un Propella® reaktorā. Ņemta vērā temperatūras, barības vielu koncentrācijas un hlora koncentrācijas ietekme. Rezultātu salīdzinājums norādīja, ka matemātiskā modeļa aprakstītās hlora, barības vielu un baktēriju skaita izmaiņas ir līdzīgas gan Propella® reaktorā, gan ūdensvada caurulē.

Objective Three-dimensional characterization of the ventricular repolarization by the T vector and T vector loop morphology in coronary artery disease (CAD), and their response to short-term (no flow) ischemia induced by coronary occlusion during a percutaneous intervention (PCI). Background The risk for sudden cardiac death is increased in conditions of acute or permanently heterogeneous ventricular repolarization, for which ischemia is a risk factor. Methods Fifty-six CAD patients without visible collateral circulation were studied during an elective single-vessel PCI, and 10 healthy controls twice at rest. T vector parameters (Televation, Tazimuth, and QRS-T angle), and T loop parameters (Tarea, Tavplan, and Teigenv) were measured by vectorcardiography. ST vector magnitude (ST-VM) and its change (STC-VM) were used for reference. Results At rest, T vector loop morphology (Tarea, Teigenv) was significantly different in CAD patients and controls, while T vector angles did not separate the groups. Ischemia induced significant changes in T loop parameters in the entire CAD group, whereas in the LAD subgroup significant changes were seen also in T vector angle. The T loop morphology was significantly different at baseline and a more pronounced response to ischemia (Tarea) was seen in patients with, than in those without, a history of hypertension. Conclusion T loop morphology, rather than the T vector angle, separated CAD patients from healthy controls. Coronary occlusion had significant impact on ventricular repolarization, as assessed by T vector and morphology analysis, and most prominently in the LAD group. Hypertensive patients appeared especially vulnerable to ischemia.

Pētījums par dzeramā ūdens uzskaites problēmām Rīgā.

A new set of tree-ring records from the Andes of northern Patagonia, Argentina (41° S) was used to evaluate recent (i.e., last 250 years) regional trends in tree growth at upper treeline. Fifteen tree-ring chronologies from 1200 to 1750 m elevation were developed for Nothofagus pumilio, the dominant subalpine species. Samples were collected along three elevational transects located along the steep west-to-east precipitation gradient from the main Cordillera (mean annual precipitation > 4000 mm) to an eastern outlier of the Andes (mean annual precipitation > 2000 mm). Ring-width variation in higher elevation tree-ring records from the main Cordillera is mainly related to changes in temperature and precipitation during spring and summer. However, the response to climatic variation is also influenced by local site factors of elevation and exposure. Based on the relationships between Nothofagus growth and climate, we reconstructed changes in snow cover duration in late spring and variations in mean annual temperature since A.D. 1750. Abrupt interannual changes in the mean annual temperature reconstruction are associated with strong to very strong El Nino-Southern Oscillation events. At upper treeline, tree growth since 1977 has been anomalously high. A sharp rise in global average tropospheric temperatures has been recorded since the mid-1970s in response to an enhanced tropical hydrologic cycle due to an increase in temperature of the tropical Pacific. Temperatures in northern Patagonia have been anomalously high throughout the 1980s, which is consistent with positive temperature anomalies in the tropical Pacific and along the western coast of the Americas at ca. 40° S latitude. Our 250-year temperature reconstruction indicates that although the persistently high temperatures of the 1980s are uncommon during this period, they are not unprecedented. Tropical climatic episodes similar to that observed during the 1980s may have occurred in the recent past under pre-industrial carbon dioxide levels.