Improving the hyperpolarization of (31)p nuclei by synthetic design

Traditional (31)P NMR or MRI measurements suffer from low sensitivity relative to (1)H detection and consequently require longer scan times. We show here that hyperpolarization of (31)P nuclei through reversible interactions with parahydrogen can deliver substantial signal enhancements in a range of regioisomeric phosphonate esters containing a heteroaromatic motif which were synthesized in order to identify the optimum molecular scaffold for polarization transfer. A 3588-fold (31)P signal enhancement (2.34% polarization) was returned for a partially deuterated pyridyl substituted phosphonate ester. This hyperpolarization level is sufficient to allow single scan (31)P MR images of a phantom to be recorded at a 9.4 T observation field in seconds that have signal-to-noise ratios of up to 94.4 when the analyte concentration is 10 mM. In contrast, a 12 h 2048 scan measurement under standard conditions yields a signal-to-noise ratio of just 11.4. (31)P-hyperpolarized images are also reported from a 7 T preclinical scanner

Contemporary climate changes in the high mountain part of the Tatras

The purpose of the report is to determine trends in thermal and pluvial conditions in the high mountain part of the Tatras. The study makes use of the data from the weather stations on Kasprowy Wierch Mt. from the years 1951-2006, and mainly from 1966-2006. Various thermal and pluvial characteristics were considered. The increase of the rate of upward trend of temperature in the Tatras at the end of the 20th century and at the beginning of the 21st century, as well as the change of the seasonal distribution of the warming in comparison with the preceding long-term periods, have been documented. Certain symptoms of increase of the thermal and pluvial continentality have also been observed. The contemporary air temperature increase in the high mountain part of the Tatras is not followed by significant changes of the precipitation amount and nature

The cyclical changes of air temperature in Poland

The dissertation takes up the problem of homogeneity of the air temperature field in Poland in terms of cyclical fluctuations. The thermal conditions within the area of Poland were described through the chronological series of the monthly a verages of air temperature, registered at 58 stations of the Institute of Meteorology and Water Economy in the years 1951-1990. The spatial differentiation was determined of the periods, amplitudes, and phases of the identified short-term fluctuations of air temperature, and the synchronicity of these fluctuations on the area of Poland was demonstrated. An objective of the study was constituted, as well, by the identification of the natural causes of the periodicity of air temperature changes - demonstration of the synchronicity (correlation) of the cycles of air temperature, atmospheric circulation, and solar activity. An attempt was also undertaken of determining the share of the short-term variability in the observed trends of air temperature in Poland. The significant cyclical components identified on the basis of the data from the years 1951-1990 were made use of in the forecast of air temperature in Poland for the decades to come

Short cycles of changes of thermal conditions in Poland in the years 1951-1990

The paper constitutes a continuation of the studies of spatial differentiation of the short-term air temperature changes in Poland. The study was undertaken with the aim of identification of the cyclical changes of temperature depending upon the season of the year. The starting point for the inquiry was the set of monthly average air temperatures for the years 1951-1990, coming from 58 weather stations of the Institute of Meteorology and Water Management. The basis for statistical inference was constituted by the chronological sequences of consecutive seasonal three-month averages (Spring: March through May; Summer: June through August; Autumn: September through November, and Winter: December through February). The actual cycles of the air temperature were determined with the method of J.Boryczka, the so called "true cycles" method of identification of the dense spectra of oscillations. The results obtained from the study indicate that the short-term changes of air temperature are one of the features of thermal relations in Poland. The determined spectra of oscillations contain, depending upon the season of the year, between three and eight rhythms statistically significant at the confidence level of 0.95. The most frequently repeated cycles are the approximately 2-, 3-, 4- and 7-year ones. Among the cycles determined the strongest one, i.e. the one with the biggest amplitude and the multiple correlation coefficient, is the 7.7-year cycle for Spring and Winter and the 3.8-year cycle for Summer. Autumn is the season of the year with the greatest differentiation of individual cycles, though for the majority of weather stations the strongest cycle is the 7.0-year one. The scope of changes of the seasonal averages of air temperature values in the cycles identified is the biggest during Winter. The amplitude of temperature in the 7.7-year cycle amounts to 2.8-4.3 degrees, while in the strongest cycles of Spring, Summer and Autumn it does not exceed 2 degrees. The cycles identified do not always appear in the chronological series of temperature over the whole area of Poland. There is quite important spatial differentiation of appearance of individual cycles. The most "stable" with respect to periodical changes of air temperatures is Winter, while the least "stable" - Autumn and Summer. The distribution of parameters of individual cycles (parameters of the regression sinusoids), i.e. of length, amplitude and phase, indicates also their spatial differentiation. In spite of the fact that the paper presents the analysis of the spatial distribution of just the strongest cycles on the area of Poland, significant differences appeared

Changes of length of the vegetative period in Poland

It is commonly accepted that the vegetative period is the part of the year during which the mean daily air temperature attains at least 5°C. The report here summarized refers to the study based upon the monthly averages of air temperature from the period 1931-1990, measured at nine weather stations, representing various geographical conditions in Poland. The average dates of the beginning and end of the vegetative period confirm the regularities in the spatial distribution of these characteristics over the area of Poland, which are known from the literature of the subject. The vegetative period starts, generally, at the turn of April, and ends at the turn of November (Tables 1 and 2, Figs. 1 and 2). Length of the vegetative period ranges from 190-200 days in the north-eastern Poland to more than 230 days in the western part of the country. It is the shortest in the mountains, lasting approximately 185 days (Table 3, Figs. 1 and 3). During the 60-year period under study the earliest start of the vegetative period in the lowland part of Poland occurred on January 30th (in 1990), while the latest - on April 25th (1941, 1955). The respective extreme dates for the mountainous areas were March 25th (1934) and May 5th (1980). Thus, within the area of Poland it may happen that vegetation starts to grow already in the last week of January, but it may also start to grow as late as in the first week of May. The dates of the end of the vegetative period for the lowland Poland (Table 2, Figs. 1 and 2) range from October 9th (1946, 1976) to December 3rd ( 1951 ). In mountains the vegetative period ended the earliest on the last day of September ( 1931) and the latest - on November 18th (1963). Thus, the end of the vegetative period may occur in Poland between the last week of September and the first week of December. The length of the vegetative period (Table 3, Figs. 1 and 3) ranges from 170 days (1941) to 291 days - the latter being the absolute maximum of the period under study- in 1990. Hence, the difference between the extreme lengths of the vegetative period amounts to 121 days. In the mountains, though, the shortest vegetative period lasted 159 days (1931), while the longest - 221 days ( 1934). The analysis of the coefficients of correlation (Table 4) of the dates of the beginning and end of the vegetative period with its length showed that the length of this period is more strongly linked with the date of beginning than with the date of end. This is most probably connected with the fact that the starting date of the vegetative period in consecutive years displays greater variability than the ending date. Equations of linear regression (Table 5) indicate that the length of the vegetative period increases at the rate of 1 to 3 days per decade. This is is most probably connected with the acceleration of the start of vegetation by approximately 0.5 to 1.5 days per decade, coupled with the delay of its termination by approximately 0.5 to 1.5 days per decade. The analysis of the periodical changes (Fig. 4) showed that the 7-year cycle of the starting dates of vegetation is worth special attention, along with the 3- and 4-year cycles of the termination dates. The true length of the 7-year cycle for the start of the vegetative period gets bigger as we go from the west (7.6 years) to the east (7.9 years) of the country. The spectra of oscillations of the growing season's end are, on the other hand, characterized by high uniformity over the area of Poland

Impact of relief and land cover on the differences in the local climate of the Pinczow region

In the 1990s, the Chair of Climatology of Warsaw University conducted studies of the local climate in the Nida Basin (vicinity of Pińczów). Compared to the neighbouring areas, the researched area is characterised by specific climatic features. At the same time, this is a region with marked differences in the climatic conditions on the local scale. This results from the diversity of substratum formations, presence of large forest complexes, water bodies and areas transformed by man. The study comprised mapping, which produced a map of topoclimates in the 1 :25000 scale. In addition, meteorological observations were carried out, which allowed to develop a qualitative profile of thermal and humidity conditions in the individual units. The impact of the relief and land cover on the spatial differentiation of climate constituents in various synoptic situations was also defined. The main characteristic feature of the region's relief is the wide Nida Valley. As a concave landform, it is susceptible to the downflow of chilled air from the neighbouring areas, as a result forming pockets of chilled air to the point of reaching an inversion of temperature. At the same time, the wet soils occurring in the valley's bottom are characterised by good thermal conductivity, which can result in delaying the beginning of the occurrence of ground thermal inversion and reducing diurnal amplitude of ground and air temperature. The Pińczów and the Wodzisław hummocks surrounding the valley do not represent so spatially condensed topoclimatic units, which is due to the varied exposure and steepness of slopes, as well as to its surface formations. It is primarily the slopes of the Pińczów Hummock that enjoy favourable thermal conditions. The spacious forest complexes, which occupy large areas on the slopes of both hummocks and smaller ones in the Nida Valley, provide an additional diversity to the topoclimatic conditions