Higher Minimum Temperatures Research Articles

Factors Affecting Fungicidal Control of Entomosporium Leaf Spot of Photinia

Abstract Entomosporium leaf spot of photinia (Photinia × fraseri Dress) was epidemic throughout most of Georgia and much of the Southeast during the spring of 1991. It has been endemic for many years. The relatively high minimum temperatures recorded in December–March 1990–91 in concert with 52 days of rain during this period were conducive to disease development. Currently recommended fungicides are effective for control if they are applied on a weekly basis. Newer fungicides were effective against the fungus in laboratory culture, but labels are not approved for application to landscape or nursery plants. Spray nozzle types (flat or full cone) delivering 5 to 7 ml per second of fungicide were as effective for disease control as spray nozzles delivering four to five times more volume.

A heat-sum model to determine yield and onset of internal heat necrosis for atlantic potato

The influence of temperature on tuber yield and development of internal heat necrosis (IHN) in Atlantic (Solanum tuberosum L.) was examined in field trials in two locations over three years (seven plantings). Under simulated commercial production, yield and development of IHN varied significantly between Virginia (VA) and New Jersey (NJ) in 1986, 1987, and 1988. Marketable yield ranged from 49.8 mt.ha−1 for the early planting in 1986 in New Jersey (NJ86E) to 17.9 for VA87. Tubers developing IHN to a level which potato chip processors would rate unacceptable (off-grade) varied with year and location. Significant correlations were found between the number of days to off-grade and the mean maximum temperature for 0–30 (r = −.83), 30–60 (r = −.86) and 60–90 DAP (r = −.81) as well as the mean minimum temperature for the same periods (r = −.91,, −.80 and −.91, respectively). The relationship between yield or IHN and temperature was examined using heat-sum models with a penalty for maximum daily temperature > 25C but with or without a penalty for minimum temperature > 21C. The multiple coefficients of determination for yield were similar using either variables generated from the heat-sum model with maximum and minimum temperature penalties or from the model with maximum temperature penalty only (R2 = 0.83 and R2 = 0.82). The prediction of the time from first symptom of necrosis to off-grade (interval) was improved by including variables generated by the heat-sum model that included both the minimum and maximum temperature penalty (R2 = 0.50 vs. R2 = 0.27), respectively. High minimum temperatures as reflected in the days to maximum heat-sum were found to significantly affect tuber yield and the expression and development of IHN.

US temperature/precipitation relationships: implications for future ‘greenhouse’ climates

An analysis of monthly values of precipitation and maximum and minimum air temperatures for all 1218 stations of the US Historical Climatology Network from 1900 to 1987 suggests that, in the mean, the CO 2/trace gas-induced ‘greenhouse effect’ will probably lead to greater precipitation, lower maximum temperatures, and higher minimum temperatures, as radiatively active components of the atmosphere continue to increase in concentration.

Anomalous Temperature Dependence of the 99Tc Quadrupole Coupling and Disordering of Cesium Positions in CsTcO4

Abstract A 99T c and 133Cs solid-state NMR study of polycrystalline CsTcO4 at a field of 7.04 T and temperatures from 90 to 430 K revealed first-order quadrupole effects. 99T c quadrupole coupling constant, C q , shows anomalous positive temperature coefficients and decreases from 2.0 MHz at 430 K to 0.45 MHz at 90 K. The asymmetry parameter, η (99Tc) , is zero at 430 K and at 210 K. The high-temperature minimum of η is associated with a phase transition from orthorhombic to tetragonal and the second minimum reflects an orientational change of the principal axes qxx and qyy of the EFG-tensor. The 133Cs NMR spectra are characterised by a superposition of the two powder multiplets from the first-order couplings which arise from magnetically and crystallographically nonequivalent cesium sites, Cs (1) and Cs (2); the population ratio of Cs (2) and Cs (1), p2/p1 , varies from 2.0 at 120 K to 6.5 at 373 K. The nonequivalence and population changes are attributed to the temperature change of the crystal field potential in the vicinity of the cations.

Global warming: Evidence for asymmetric diurnal temperature change

Analyses of the year‐month mean maximum and minimum surface thermometric record have now been updated and expanded to cover three large countries in the Northern Hemisphere (the contiguous United States, the Soviet Union, and the People's Republic of China). They indicate that most of the warming which has occurred in these regions over the past four decades can be attributed to an increase of mean minimum (mostly nighttime) temperatures. Mean maximum (mostly daytime) temperatures display little or no warming. In the USA and the USSR (no access to data in China) similar characteristics are also reflected in the changes of extreme seasonal temperatures, e.g., increase of extreme minimum temperatures and little or no change in extreme maximum temperatures. The continuation of increasing minimum temperatures and little overall change of the maximum leads to a decrease of the mean (and extreme) temperature range, an important measure of climate variability.The cause(s) of the asymmetric diurnal changes are uncertain, but there is some evidence to suggest that changes in cloud cover plays a direct role (where increases in cloudiness result in reduced maximum and higher minimum temperatures). Regardless of the exact cause(s), these results imply that either: (1) climate model projections considering the expected change in the diurnal temperature range with increased levels of the greenhouse gases are underestimating (overestimating) the rise of the daily minimum (maximum) relative to the maximum (minimum), or (2) the observed warming in a considerable portion of the Northern Hemisphere landmass is significantly affected by factors unrelated to an enhanced anthropogenically‐induced greenhouse effect.

The reorientation of t-butyl groups in butylated hydroxytoluene: A deuterium nuclear magnetic resonance spectral and relaxation time study

Deuterium nuclear magnetic resonance (NMR) spectra and spin–lattice relaxation times were determined in order to study the dynamics of t-butyl groups in butylated hydroxytoluene. The results are consistent with a model first proposed by Beckmann et al. [J. Magn. Reson. 36, 199 (1979)], where there is an inequivalence between the methyl groups within each t-butyl group. While two methyl groups reorient rapidly relative to the whole t-butyl rotation, the remaining methyl group is more restricted in its motion, reorienting at a rate comparable to that of the t-butyl group itself. The spin–lattice relaxation data show two T1 minima, the high temperature minimum (40 °C) corresponding to the combined t-butyl and ‘‘slow’’ methyl rotations, and the low temperature minimum corresponding to ‘‘fast’’ methyl group rotation. Using an explicitly defined T1 fitting function, the T1 data yield activation energies of 2.2 and 6.0 kcal/mol for the fast methyl and t-butyl rotations, respectively, both in agreement with Beckmann’s values obtained from proton T1 experiments. It was also possible to simulate the low temperature deuterium NMR spectra from T=−160 °C to T=−80 °C using the aforementioned dynamical inequivalence between the t-butyl methyl groups. While the fast methyl group rotation was in the motional narrowing region for T>−160 °C, it was possible, from the simulations, to determine the t-butyl exchange rates to within 10%. The jump rates are remarkably close to the values predicted from the T1 results. Above −80 °C, the spectra could not be simulated, implying that a third motion must be present to further alter the high temperature line shapes. The effective axial asymmetry of the T>−20° spectra indicates that the additional motion involves a two site exchange.

Space VLBI and the physics of active galactic nuclei

Three related questions are considered: 1) The number of sources observable with the highest resolution of Radioastron and VSOP. 2) The ability of space VLBI to map structures in the AGN cores. 3) The use of space VLBI for testing orientation-dependent unified models of AGN. At 22 GHz Radioastron may be able to observe only a handful of sources at any given time due to the required high minimum brightness temperature, and the most useful observing strategy may be to observe repeatedly a few sources to map the geometry and the evolution of jet and shock structures. For survey-type observing programs VSOP is more suitable. By measuring apparent transverse velocities in BL Lacs and other very compact sources with space VLBI and deducing the Doppler boosting factors from continuum monitoring, orientation angles can be determined and the relationship between different classes of AGN established.

The Impact of Increasing Summer Mean Temperatures on Extreme Maximum and Minimum Temperatures in Phoenix, Arizona

Abstract Over the past few decades, heat-island related temperature increases in Phoenix, Arizona have been similar to the temperature increases predicted in a number of greenhouse simulation experiments. In this investigation, we use the Phoenix climate record to assess how increasing summertime mean temperatures are related to changes in the extreme maximum and minimum temperatures. Generally, rising mean temperatures are associated with substantial changes in the occurrence of extreme minimum temperatures (e.g., fewer days of extreme low minimum temperatures and more days of extreme high minimum temperatures). However, while the rising mean temperatures strongly influence the occurrence of moderately high maximum temperatures, they are weakly associated with the occurrence of extreme maximum temperatures. The results suggest that considerable caution should be used in predicting the occurrence of extreme temperatures from projected increases in mean temperature levels.

Interstitial Thermoradiotherapy

Interstitial hyperthermia (IHT) combined with brachycurietherapy (thermoradiotherapy) has gained increasing popularity among radiation oncologists due to its potential as an effective radio- and chemosensitizer. IHT offers considerable advantages over percutaneous methods: confined treatment volume, better sparing of normal tissue, accessibility of deeper tumors, more homogeneous therapeutic temperature distribution, and better control and evaluation of thermal parameters using extensive "thermal mapping" procedures. This article addresses technical principles and clinical applications of IHT methods, radiofrequency (RF), microwave (MW), and hot source (HS) hyperthermia. Clinical phase I/II studies have used IHT palliatively for primary advanced, persistent, or local recurrent tumors, which have responded poorly to conventional treatment. The preliminary clinical data on greater than 500 patients treated with interstitial thermoradiotherapy are extremely promising despite the broad variation among the different treatment approaches. The observed complete response (CR) rate in various clinical trials ranges between 11 and 74%. The differences between the various techniques are minor, with a CR of 57% for interstitial RF hyperthermia (169 of 299 patients) and 60% for interstitial MW hyperthermia (130 of 215 patients). Despite extensive pretreatment, the total observed compliation rate of 22% for RF hyperthermia (67 of 299) and 21% for MW hyperthermia (45 of 215) is acceptable. The prognostic treatment factors identified are tumor volume, applied radiation dose, sufficiently high minimum tumor temperatures, and good thermal parameters, i.e., good quality of the hyperthermia treatment sessions. Technical innovations may facilitate and improve clinical applications and should allow broad clinical implementations of IHT, e.g., intraoperative hyperthermia, and even intracavitary hyperthermia. From these experiences it would appear that IHT is an effective and safe treatment modality, especially when combined with radiotherapy for tumor palliation. Prospective randomized multicentric studies have already been initiated to investigate its role in palliative and adjuvant tumor therapy.

Primary advanced and local recurrent head and neck tumors: effective management with interstitial thermal radiation therapy.

Thirty-seven patients with 18 primary advanced or persistent, 16 local recurrent, and three local metastatic tumors of the head and neck were treated with a combination of interstitial low-dose iridium-192 radiation therapy and interstitial 915-MHz microwave hyperthermia supplemented by external radiation therapy. Twenty-eight lesions received an additional external radiation dose of 21-61 Gy. Interstitial hyperthermia was applied immediately before Ir-192 was placed and after its removal for 45-60 minutes at 41 degrees C-44 degrees C. Follow-up ranged from 4 to 45 months. At 3 months, complete remission occurred in 25 lesions (68%); partial remission, in nine (24%); and no change or progressive disease, in three (8%). At 12 months of follow-up in 32 lesions, local control was achieved in 23 (72%), with the patients alive, and in four (12%), with the patients dead. There were five local recurrences, one of which occurred after complete response. Lesion type, tumor volume, radiation dose, and thermal quality at high minimum temperature were identified as prognostic factors influencing complete remission. The combined treatment was well tolerated.

Proton NMR Study of Molecular Dynamics in Hydrazinium Perchlorate

Abstract The proton spin-lattice relaxation time T1 (at 5.4, 10 and 15 MHz) and second moment M2 (at 9.8 MHz) have been measured in hydrazinium Perchlorate (N2H5ClO4). The temperature dependence of T, shows two minima. The low temperature T, minimum has been explained in terms of NH3 reorientation about the N-N axis while the high temperature minimum is attributed to the exchange of protons within the NH2 group (180° flip about the H - N - H bisectrix). The activation energies for NH3 and NH: motions are found to be 20.5 kJ mol-1 and 39.8 kJ mol-1 , respectively. The second moment variation with temperature shows two transitions around 120 K and 210 K and has been discussed in terms of NH3/NH2 motions.

Young high-temperature granulites from the base of the crust in central Mexico

CHARACTERIZATION of the lower continental crust is essential to understanding processes of crustal formation and evolution. Many workers have concluded that the lower crust is composed of granulite-facies rocks (see, for example, refs 1, 2), but many exposed granulite-facies terranes seem to have mid-crustal rather than lower-crustal origins3–5. Here we present new data from direct samples of the lower continental crust, in the form of metapelitic rock fragments brought to the surface by Quaternary volcanism in central Mexico. These xenoliths contain exsolved ternary feldspars that record extremely high minimum metamorphic temperatures of 950–1,100 °C, the highest yet known to be preserved in deep-seated metamorphic rocks. The metamorphism seems to be the result of underplating by basaltic magma and to be regional in extent. Our barometry on these samples demonstrates that granulite-facies metamorphic rocks are present in the lower crust, and provides important constraints on tectonic models and interpretations of geophysical data. Chemical and text lira I evidence suggest that the xenoliths were not able to cool to below 850–900 °C before being entrained in their host magmas, indicating that the granulite-facies metamorphism occurred no more than ~30 Myr ago.

Meteorological aspects of the infestation of some Pests on jowar crop

The possible linkage between different meteorological elements and a few pests of jowar, like stem-borer, earhead bug and mite. based on the statistical analysis of the past 7 to 13 years records is derived in this study. Data of kharif jowar crops at Dharwar and Coimbatore is utilized. The simple and multiple linear regression techniques are adopted.
 It is found that higher maximum temperature. minimum temperature >13°C and relative humidity >70% during November-December are favorable for stem-borer attacks: The optimum miximum temperature of 28°C in November and 31°C in August are obtained for earhead bugs incidences. Their activities are suddenly decreased at minimum temperature > 17°C in December at Coimbatore but increases when it is > 18°C during October at, Dharwar. Jowar mites show enhancements In activity with Increase In maximum temperature (30 C) during July higher minimum temperature (20°C) during November, sunshine hours of greater than 7 in July and a weekly rainfall of 80-90 mm during last week of September at Coimbatore.
 After corroborating with the actual observations, these results may be useful in essuing forewarnings of, the incidences of these pests on jowar .
 

Molecular motional and structural study of ammoniated titanium disulfide by proton NMR

Proton spin-lattice relaxation times and linewidths have been measured as a function of temperature at 25 MHz for (NH 4 +) 0.21Ti 2 0.21− and at 25 and 50 MHZ for (NH 4 +) 0.22(NH 3) 0.37TiS 2 0.22−. In the former compound, the NH 4 + cations reorient randomly and rapidly on trigonal prismatic sites in the van der Waals gap of TiS 2, and there is no evidence of other thermally activated motion between 3 K and the deintercalation temperature. In the latter compound, two distinct types of motions can be discerned from their characteristic NMR signals. At lower temperatures the NH 3 molecules rotate about their three-fold axes and above 270 K translational diffusion occurs. An average proton-proton distance of 1.79±0.03 A ̊ in NH 3 has been evaluated from the temperature dependence of the relaxation time associated with the C 3 axis rotation. This large distance relative to that in normal pyramidal NH 3 (1.65 Å) is consistent with a planar NH 3 geometry and perhaps some lengthening of the normal NH bond length (1.008 Å). The activation energy for NH 3 rotation (2.41 ± 0.02 kcal/mol NH 3) is nearly equal to that measured in solid NH 3 (2.3 kcal/mol NH 3). A high-temperature minimum in the relaxation time has been attributed to NH 3 diffusion, with an activation energy (13.3±3kcal/mol NH 3) that is in good agreement with the NH 3 deintercalation enthalpy.

Dynamical evidence of hydrogen sublattice melting in metal-hydrogen systems

Measurements of the temperature dependence of the proton and deuteron spin-lattice relaxation time T 1 in cubic fluorite (CaF 2) structure dihydrides and dideuterides (MH 2 and MD 2) show a second high temperature turndown in T 1 in addition to the usual minimum associated with the independent hopping motion of H(D) among tetrahedral (T) interstitial sites at lower temperatures. The close analogy to the motion of anions in fluorite structure superionics suggests that the high temperature minimum indicates the onset of strongly correlated hydrogen motion, possibly accompanied by the occurrence of long-lived hydrogen clusters.

Climatic effect on alfalfa dry matter production Part II. Summer harvests

Current information is inadequate to define those environmental variables most important in alfalfa ( Medicago sativa L.) summer dry matter production and those associated with successive yield declines in the Northern U.S.A. Such knowledge is useful in alfalfa modelling strategies requiring the use of production-environmental relationships and in management stategies aimed at optimizing production throughout the season. The purpose of this study was to define for a three-harvest management system those environmental variables most important to early and late summer production and those related to summer yield declines (i.e., summer slump). Multiple regression analysis was used on 21 years of climate-yield data from the University of Minnesota Agricultural Experiment Station at Rosemount to delineate those important variables in the first three production years. Early summer yields were positively and negatively affected by solar radiation and wind, respectively, accounting for 24% of the explained variability in the first production year. In the second production year, minimum air temperature had a negative effect on early summer yield and accounted for 37% of the variability in yields. Potential evapotranspiration ( PET) had a positive effect on yield and accounted for 33% of the variability in the third production year. Late summer yields in the first production year were dependent on the early summer moisture ratio of precipitation to PET. The negative relationship indicated that a dry period preceding late summer growth was beneficial to yields. Minimum air temperatures had a positive effect on yields in the second production year and accounted for 48% of the yield variability. In the third production year, precipitation accounted for 61% of the yield variability and had a positive effect on yields. Reduction in yields from spring to early summer harvest was most closely associated with the occurrence of dry springs and high minimum air temperatures in the early summer period. The yield reduction between successive summer harvests was associated with low precipitation in the late summer period. Results indicate that the relative importance of environmental variables to yield varies as the stand ages and that their effect can change over the course of the season (i.e., the effect of minimum air temperature on yield was negative in early summer and positive in late summer). These considerations should be accounted for in alfalfa growth models.

Dynamical evidence for a change in hydrogen-diffusion behavior in transition-metal hydrides at high temperatures.

The /sup 45/Sc nuclear spin-lattice relaxation time T/sub 1/ in scandium dihydride and dideuteride measured up to 1300 K shows a second high-temperature minimum at --1100 K, in addition to the usual (Bloemberger-Purcell-Pound) minimum associated with independent motion of hydrogen vacancies among tetrahedral interstitial sites. This indicates the onset of a second mode of hydrogen motion with a relatively long associated correlation time for the hydrogen-scandium interaction. Possible origins for such long times are discussed.

リンゴの早期落果に関与する気象要因の解析と栽培管理

The early fruit drop of ‘Starking Delicious’, ‘Mutsu’, ‘Redgold’ etc. occurred largely in the north of Akita prefecture in 1978. We tried to clarify the effects of weather conditions on the early fruit drop by investigating the weather conditions in 1978, and analyzing statistically the relationship between those in 1979-1985 and the rate of early fruit drop.In 1978, early fruit drop occurred from the 36th day after full bloom. From the 31st day after full bloom the maximum and minimum temperatures were much higher, from the 27th day to the 38th day after full bloom the duration of sunshine was less and the precipitation was more than the mean value of the previous 10 years.The rate of early fruit drop in 1979-1985 was closely correlated with the weather conditions around the 30th day after full bloom; the multiple regression equation which expresses the rate of early fruit drop was obtained using the minimum temperature, the duration of sunshine and the precipitation from the 28th day to the 34th day after full bloom. From these results, it was shown that the early fruit drop was induced by a higher minimum temperature and less sunshine.We also investigated the effects of tree vigor and pruning on the early fruit drop. To estimate the vigor of each tree, elongation of the terminal shoot was measured regularly and the mineral constituents of leaves were analyzed. The rate of early fruit drop was increased in both vigorous and weak trees, and was closely correlated with the elongation of the terminal shoot. Similar results were observed in heavily pruned trees, that is, heavy pruning increased the elongation of the terminal shoot and early fruit drop.

Electrical resistivity of amorphous and crystalline (Co 1- xMn x) 2B alloys

Electrical resistivity of crystalline (Co 1- x Mn x ) 2B compounds showed the temperature dependence similar to that of usual ferromagnetic alloys except for resistivity minimum at low temperature. Two kinds of resistivity minima were observed for amorphous alloys. The high temperature minimum was ascribed to magnetic ordering and the low temperature one to the Kondo effect.

Inflation and non-minimal supergravity

Inflation based on a single chiral superfield (the inflaton) in N = 1 supergravity has been shown to be incompatible with the so-called thermal constraint requiring a high temperature minimum at a point at which the zero-temperature scalar potential is flat, in a theory using fields with minimal scalar kinetic terms. Here we show that by modifying the kinetic terms of the inflaton, one can satisfy the thermal constraint without introducing additional fields or small parameters.