• Journal of Life Science
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• v.10 no.1
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• pp.52-60
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• 2000

Up to now, there have been done much efforts in regard to nitrate reductase activity (NRA) of dicotyledonous herbs and important crop monocotyledons, but few to wild plants having canopy structure such as Carex. The objective of the present study are to determine: a) the optimum in vivo NR assay conditions for leaf samples of Carex species, b) changes of NRA according to section within leaf and leaf ages, c) diurnal variations. Optimized assay media of each Carex species were determined. NRA of C. rostrata adapted to oligotrophic habitats is readily saturated at lower substrate concentration than those of C. distans and C. gracilis, adapted to meso- and eutrophic habitats, respectively. All Carex species investigated have higher NRA in leaves than in roots. NRA of all species showed maximal values at the middle section of each leaf and in the youngest fully expanded leaves. Compared to C. gracilis, NR in leaves of C. distans was adapted readily to the light period. On the whole, Carex showed rather delayed diurnal variation. Even if the in vivo nitrate reductase assay based on nitrite estimation does not give an accurate estimation of total nitrate reduced, it still serves as a useful tool to find out relative differences in varying environmental conditions. Additionally, in vivo RNA measurements are helpful to understand nitrate reduction and basic nitrogen metabolism of Carex species having different canopy structure.

• Journal of Korean Neurosurgical Society
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• v.65 no.1
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• pp.151-160
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• 2022

Continuous monitoring of intracranial pressure is a well established medical procedure. Still, little is known about long-term behavior of intracranial pressure in normal pressure hydrocephalus. The present study is designed to evaluate periodicity of intracranial pressure over long-time scales using intraventricular pressure monitoring in patients with normal pressure hydrocephalus. In addition, the circadian and diurnal patterns of blood pressure and body temperature in those patients are studied. Four patients, selected with "probable" normal pressure hydrocephalus, were monitored for several dozen hours. Intracranial pressure, blood pressure, and body temperature were recorded hourly. Autocorrelation functions were calculated and cross-correlation analysis were carried out to study all the time-series data. Autocorrelation results show that intracranial pressure, blood pressure, and body temperature values follow bimodal (positive and negative) curves over a day. The cross-correlation functions demonstrate causal relationships between intracranial pressure, blood pressure, and body temperature. The results show that long-term fluctuations in intracranial pressure exhibit cyclical patterns with periods of about 24 hours. Continuous intracranial pressure recording in "probable" normal pressure hydrocephalus patients reveals circadian fluctuations not related to the day and night cycle. These fluctuations are causally related to changes in blood pressure and body temperature. The present study reveals the complete loss of the diurnal blood pressure and body temperature rhythmicities in patients with "probable" normal pressure hydrocephalus.

• Anxiety and mood
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• v.8 no.2
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• pp.93-98
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• 2012

Objective : Cortisol, a product of hypothalamus-pituitary-adrenal axis (HPA axis), is one of our defensive mechanisms in response to stress. The level of cortisol in the saliva is a major biomarker of the stress response by HPA axis and shows diurnal variation. We measured salivary cortisol level and its diurnal variation to compare the pattern of changes by degree of burn and Clinician-Administered PTSD Scale (CAPS) score. Methods : We measured the salivary cortisol levels of 37 subjects hospitalized in the burn center at our facility from March to June 2012. Salivary cortisol levels were measured at 6 : 00 AM and at 7 : 00 PM. All subjects were tested for CAPS to evaluate the severity of posttraumatic stress disorder and the Hamilton Depression Rating Scale to evaluate and to control the coexisting depression. Results : Factorial ANOVA test revealed that there was a statistically significant difference in terms of the effect of the interaction between the degree of burn and the patient's CAPS score. Unlike the mild burn group, in the severe burn group, the patients who had a low CAPS score didn't show a normal diurnal variation and the patients who had a high CAPS score showed the normal diurnal variation. After a few months follow up, we found a greater degree of psychiatric complications in severe burn patients that had a lower cortisol stress response. Conclusion : We suppose that the disappearance of the stress response changes in salivary cortisol seen in the severe burn group may be caused by an impaired stress response. Through followed observation of the subjects, this disruption of cortisol response may cause psychiatric problems afterwards.

• Journal of the Korean association of regional geographers
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• v.17 no.2
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• pp.167-180
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• 2011

This paper investigates the changes of diurnal temperature range (DTR) by season and region in South Korea using daily maximum temperature and daily minimum temperature from 1954 to 2009. It also attempts to find what causes these changes. The daily minimum temperature distinctively increased during the latter half of the research period (1988~2009) than the first half of the year (1954~1987) leading decreases in DTR, while the rise in daily maximum temperature was not distinct during the research period. The DTR shows slightly increasing trend in spring. but decreasing trend in fall. The DTR is decreasing in urban region while it is increasing in rural area. The degree of the DTR decrease is bigger in large urban region than in medium-small urban region. The DTR in urban region is affected by the amount of clouds in spring and tile duration of sunshine in fall. The DTR in rural area is affected by the amount of clouds in spring and the number of days with precipitation in fall.

• Journal of Crop Science and Biotechnology
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• v.10 no.3
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• pp.163-166
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• 2007

Diurnal changes in levels of endogenous gibberellins(GAs) were investigated in three rice cultivars i.e. Sangjubyeo, Shingeumobyeo(photo-neutral) and Chucheongbyeo(photosensitive). The rice cultivars were grown under a 12-hr photoperiod and endogenous GA levels were assayed by gas chromatography-mass spectrometry(GC-MS-SIM) every 3 h for 24 h. The endogenous bioactive $GA_1$ and its immediate precursor $GA_{20}$ contents were significantly different in both photosensitive and photo-neutral rice cultivars, though less pronounced differences were observed for endogenous $GA_{12},\;GA_{53},\;GA_{19}$, and $GA_8$ levels with in the three rice cultivars. The levels of bioactive $GA_1$ and its immediate precursor $GA_{20}$ were significantly higher in Chucheongbyeo than in the other two cultivars. In Chucheongbyeo, the $GA_1$ contents increased significantly from 11.00 to 17.00 o'clock, thus indicating a correlation with light. In Shingeumobyeo, $GA_1$ contents slightly increased during morning hours, while a similar hike in $GA_1$ contents was observed for Sangjubyeo during evening hours. $GA_{19}$ was found to be the most abundant GA form in the three rice cultivars. Our results suggested that GA production in rice depends upon the response potential of rice cultivars and that light positively correlated to GA production in photosensitive rice cultivar.

• Atmosphere
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• v.31 no.3
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• pp.295-309
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• 2021

Diurnal variations of air temperature and relative humidity in the Urban Canopy Layer (UCL) of the Seoul metropolitan area are examined using the Weather Research and Forecasting model coupled with the Seoul National University Urban Canopy Model. The canopy layer air temperature is higher than 2-m air temperature and exhibits a more rapid rise and an earlier peak in the daytime. These result from the multiple reflections of shortwave radiation and longwave radiation trapping due to the urban geometry. Because of the absence of vegetation in the UCL and the higher canopy layer air temperature, the canopy layer relative humidity is lower than 2-m relative humidity. Additional simulations with building height changes are conducted to examine the sensitivities of the canopy layer meteorological variables to the urban canyon aspect ratio. As the aspect ratio increases, net sensible heat flux entering the UCL increases (decreases) in the daytime (nighttime). However, the increase in the volume of the UCL reduces the magnitude of change rate of the canopy layer air temperature. As a result, the canopy layer air temperature generally decreases in the daytime and increases in the nighttime as the aspect ratio increases. The changes in the canopy layer relative humidity due to the aspect ratio change are largely determined by the canopy layer air temperature. As the aspect ratio increases, the canopy layer relative humidity is generally increased in the daytime and decreased in the nighttime, contrary to the canopy layer air temperature.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2006.05a
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• pp.419-420
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• 2006

• The Korean Journal of Ecology
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• v.19 no.5
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• pp.453-463
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• 1996

Diurnal changes of microclimatic conditions and tissue water relations were measured at two sites where Carpinus laxiflora and C. cordata were allopatrically distributed. The microclimatic conditions at a site where C. laxiflora was distributed produced severe water stress condition during summer months. Daily maximum temperature reached $30.4^\circC$ and the highest vapor pressure deficit was 1.31 KPa when 13 rainless days were continued. During this period soil water content decreased to below the field capacity even at a depth of 20 cm and xylem pressure potential also decreased to ­2.04 MPa. However, turgor potential was maintained more than 0.4 MPa. Patterns of stomatal conductance were changed with evaporative demand and soil water availability. On the other hand, microclimatic conditions at a site where C. cordata was distributed were moderate water strees condition compared with those at a site C. laxiflora was distributed. Though soil water content was maintained above field capacity C. cordata showed a remarkable decrease in turgor potential and stomatal conductance throughout the experiment. These results indicate that there is a difference in habitat characteristics between the two species and C. laxiflora is more resistant than C. cordata to water stress.

• The Korean Journal of Ecology
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• v.21 no.1
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• pp.89-96
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• 1998

The diurnal changes of the stomatal conductance, transpiration and leaf water potential were measured in order to assess the water relations characteristics of Pueraria thunbergiana in August of 1995 and 1996. The results showed two different responses depending on the duration of rainless days. The microclimatic conditions were highly stressful on 2 August. Daily maximum temperature reached to $39.0{\circ}C$ and vapor pressure deficit was 3.55 KPa. During this time the leaf water potential decreased to -1.02 MPa and a marked reduction of stomatal conductance was shown. However, on 15 August the stomatal conductance increased with increment of photon flux density, and transpiration was highly maintained during the day time. Minimum leaf water potential was only -0.47 MPa in spite of high transpiration rate. Furthermore, on 15 August reduced leaf water potential during the day time was recovered rapidly with decrease of photon flux density, whereas recovery of leaf water potential on 2 August was delayed. However, reduced leaf water potential on 2 August was recovered untile the next dawn. Osmotic potential at turgor loss point of Pueraria thunbergiana on 2, 3 and 15 August was -1.79, -1.70 and -1.60 MPa, respectively. The vapor pressure deficit is more contributive to the regulation of stomatal conductance than leaf water potential.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.26 no.1
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• pp.45-50
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• 1981

Diurnal changes in leaf stomatal resistances were measured on leaf positions and both surfaces to investigate the stomatal response to irradiance in wheat, var. Chokwang and barley, var. Dongbori 1. Stomatal frequency and size were also determined to explain the control mechanism of gas exchanges in two species. The leaf diffusive resistances of two species decreased, as the sun rose, to minimum at 10 to 11 o'clock a.m. and increased gradually in the afternoon, even faster at sunset. As the adaxial irradiance increased, stomatal resistances decreased sensitively in the range of 30uEm$^{-2}$ㆍsec$^{-1}$ to 150uEm$^{-2}$ㆍsec$^{-1}$ quantum flux density. The stomatal opening of the abaxial surface began at lower irradiance and was completed earlier than the adaxial surface. The adaxial irradiances decreased in order of leaf position, flag, the 2nd, the 3rd leaf, and the stomatal resistances increased in the same order. Even under the same irradiance, the stomatal resistance of lower leaves were higher than those of upper leaves. The stomatal frequencies of lower leaves were less, but the stomatal size was greater than those of upper leaves. Consequently, the relative leaf area occupied by stomatal pores were constant among leaf positions in two species.