Background: “The absolute refractory” period is the time interval during which the nerve fiber is in capable of conducting another impulse after a conditioning stimulus and the determination of the refractory period distribution in a nerve can give a good idea about the characteristics of the conducting fibers constituting that nerve as it reflects their excitability and could be used as a sensitive indicator for the ability of the nerve fiber to conduct pairs of closely spaced impulses.
Methods: The new collision test was used to measure precisely the absolute motor refractory period and the paired shock technique to measure the absolute sensory refractory period in the ulnar nerves of 167 normal infants and children to identify age related changes in the excitability of the nerve fiber membrane.
Results: These tests showed that changes in the membrane properties of the fastest and the slowest motor and sensory fibers differ with age. Fastest fibers have more prominent and rapid reduction in their absolute refractory periods (increased excitability) at the successive age groups during the period between 6 months to 6years of life, while the slowest ones have more gradual and prolonged membrane changes (as assessed by the dispersion of the refractory periods)
Conclusion: These electrophysological findings point to a period of rapid increment in the nerve fiber diameter, myelin thickness and the possibility of addition of new functioning nerve fibers during the process of growth and development, since each fiber has its characteristic absolute refractory period from birth.
In this paper we introduce a new class of operators on Hilbert space. We
call the operators in this class, n,m- powers operators. We study this class
of operators and give some of their basic properties.
Abstract:
This tribe had lived in Iraq since the first century A.D. Persia tried to
keep this tribe away from Iraq, but without result. The tribe managed to get
victory against Persia in the battle of Dhyqar.
When the Muslims had come to conquer Iraq, Rabi’a welcomed them
and takes part in that action.
That tribe helped the caliph Ali in the Jammal and Sifffen wars in order
to remain Iraq the center of the Islamic caliphates this tribe had felt very sad
and sorrowful when the caliphate become to the Umayyad . This tribe did not
give up, so this tribe did what could be done to help those who had revolted
against the Umayyad. Rabi’a did that in order to get ride of the Mudriat alsham,
and favored Rabi
The rapid increase in the number of older people with Alzheimer’s disease (AD) and other forms of dementia represents one of the major challenges to the health and social care systems because of a large number of people affected. Early detection of AD makes it possible for patients to access appropriate services and to benefit from new treatments and therapies, as and when they become available, and to plan for the future. The onset of AD starts many years before the clinical symptoms become clear. A biomarker that can measure the brain changes in this period would be useful for early diagnosis of AD. Potentially, the electroencephalogram (EEG) can play a valuable role in early detection of AD. Damage caused to the brain due to AD leads t
... Show MoreThe present study was conducted using 16 adult male Swiss albino mice (weighing 40-50g). They were equally divided into four experimental groups. The first group was only given tap water as control during experimentation period (40 days). Group II, group III and group IV of mice were daily given a subcutaneous injection of cobalt as cobalt chloride (CoCl2) at a dose of 20mg, 40mg, and 60mg /Kg body weight respectively. The examination of the histological sections of the second experimental group of mice (low dose group) showed no particular changes in the columnar epithelial cells of the duodenum of mice. The examination of the histological sections of the third experimental group of mice (moderate dose group) showed abundant degenerativ
... Show MorePlasma generated by a 1064 nm pulsed Nd: YAG laser with pulse duration of 10 ns concentrated onto an Al solid target under vacuum pressure was examined spectroscopically. The temperature and electron density specifying the plasma were measured by time-resolved spectroscopy of neutral atom and ion line emissions in the time period range of 300–2000 ns. An echelle spectrograph is utilized to appear the plasma emission lines. The temperature was obtained using the spectral line comparison method and the electron density was calculated using the Stark Broadening (SB) method. The electron density was characterized as a function of laser pulse energy. The time range where the plasma is optically thin and is also in local thermodynamic equilibri
... Show MoreOpenStreetMap (OSM) is the world’s biggest publicly licensed geographic data collection. Because OSM is rapidly being used in a wide range of applications, researchers have focused their efforts on determining its quality. The OSM buildings data quality is still ambiguous, due to the limitations, and a few researchers have evaluated the OSM buildings data quality through difficulties where the authoritative data are not obtainable. The focus of this research is to analyze and assess the accuracy of OSM buildings including completeness, and positional accuracy methods. Two different study areas in Baghdad city-Iraq have been investigated: Al-Rasheed and Al-Karrada. The process of the (OSM) data evaluation involved identifying the correspon
... Show MoreThis paper introduces some properties of separation axioms called α -feeble regular and α -feeble normal spaces (which are weaker than the usual axioms) by using elements of graph which are the essential parts of our α -topological spaces that we study them. Also, it presents some dependent concepts and studies their properties and some relationships between them.
Background: The events in pregnancy elicit one of the best examples of selective anatomical, physiological and biochemical adaptations, with profound changes in respiratory physiology. The changes in respiratory physiology are due to increased size of the fetus with advance gestation which constitutes a mechanical impediment to normal process of ventilation.
.Patients and methods: This study started from the 1st of Nov. 2009 till the 30th of Oct. 2010. pregnant women aged (16-44 years) of different weight, height and different conception from 1st, 2nd, 3rd trimester and post term were included. Spirometry was performed in Baghdad teaching hospital( pulmonary fun
... Show MoreAlzheimer’s disease (AD) is a progressive disorder that affects cognitive brain functions and starts many years before its clinical manifestations. A biomarker that provides a quantitative measure of changes in the brain due to AD in the early stages would be useful for early diagnosis of AD, but this would involve dealing with large numbers of people because up to 50% of dementia sufferers do not receive formal diagnosis. Thus, there is a need for accurate, low-cost, and easy to use biomarkers that could be used to detect AD in its early stages. Potentially, electroencephalogram (EEG) based biomarkers can play a vital role in early diagnosis of AD as they can fulfill these needs. This is a cross-sectional study that aims to demon
... Show More