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Laser Doppler Imaging
Laser Doppler imaging (LDI) is an imaging method that uses a laser beam to scan live tissue. When the laser light reaches the tissue, the moving blood cells generate doppler components in the reflected ( backscattered) light. The light that comes back is detected using a photodiode that converts it into an electrical signal. Then the signal is processed to calculate a signal that is proportional to the tissue perfusion in the scanned area. When the process is completed, the signal is processed to generate an image that shows the perfusion on a screen. The laser doppler effect was first used to measure microcirculation by Stern M.D. in 1975. And it is used widely in medicine, some representative research work about it are these: Use in Ophthalmology The eye offers a unique opportunity for the non-invasive exploration of cardiovascular diseases. LDI by digital holography can measure blood flow in the retina and choroid. In particular, the choroid is a highly vascularized tissue s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microangiography
Microangiography ( ) is a type of angiography that consists of the radiography of small blood or lymphatic vessels of an organ. While most other types of angiography cannot produce images of vessels smaller than 200 µm in diameter, microangiography does just that. A microangiographic image is the result of injection of a contrast medium into either the blood or the lymphatic system and, then, enlargement of the resulting radiograph. Thus, an image is obtained in which there is contrast between vessel and surrounding tissue. It is often used in order to detect microvascular lesions in organs. But, it has been suggested that microangiography can also be used to detect tumors through visualization of tumor-induced small blood vessels. This is because tumor growths require vascularization before they can develop more rapidly. A few of the commonly used types are fluorescent, silicone rubber, and synchrotron radiation microangiography. Common types Fluorescent microangiography ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Systole
Systole ( ) is the part of the cardiac cycle during which some chambers of the heart contract after refilling with blood. The term originates, via New Latin, from Ancient Greek (''sustolē''), from (''sustéllein'' 'to contract'; from ''sun'' 'together' + ''stéllein'' 'to send'), and is similar to the use of the English term ''to squeeze''. The mammalian heart has four chambers: the left atrium above the left ventricle (lighter pink, see graphic), which two are connected through the mitral (or bicuspid) valve; and the right atrium above the right ventricle (lighter blue), connected through the tricuspid valve. The atria are the receiving blood chambers for the circulation of blood and the ventricles are the discharging chambers. In late ventricular diastole, the atrial chambers contract and send blood to the larger, lower ventricle chambers. This flow fills the ventricles with blood, and the resulting pressure closes the valves to the atria. The ventricles now perform i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hot-wire Anemometry
In meteorology, an anemometer () is a device that measures wind speed and direction. It is a common instrument used in weather stations. The earliest known description of an anemometer was by Italian architect and author Leon Battista Alberti (1404–1472) in 1450. History The anemometer has changed little since its development in the 15th century. Alberti is said to have invented it around 1450. In the ensuing centuries numerous others, including Robert Hooke (1635–1703), developed their own versions, with some mistakenly credited as its inventor. In 1846, John Thomas Romney Robinson (1792–1882) improved the design by using four hemispherical cups and mechanical wheels. In 1926, Canadian meteorologist John Patterson (1872–1956) developed a three-cup anemometer, which was improved by Brevoort and Joiner in 1935. In 1991, Derek Weston added the ability to measure wind direction. In 1994, Andreas Pflitsch developed the sonic anemometer. Velocity anemometers Cup anemome ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vasocongestion
Vasocongestion, vascular congestion or vascular engorgement is the swelling of bodily tissues caused by increased vascular blood flow and a localized increase in blood pressure. Typical causes of vasocongestion in humans includes menstruation, sexual arousal, REM sleep, strong emotions, illnesses, deep venous thrombosis (DVT) and allergic reactions. Illnesses Menstrual cramps are one of the most common side effects of vasocongestion in adult females. Although pain and discomfort varies among individuals, vasocongestion is an essential part of the shedding of the lining of the uterus. Abnormal vasocongestion during the menstrual cycle can lead to irregular bleeding, severe and debilitating cramps and anemia caused by increased menstrual flow. The temporary vasocongestion of the cheeks of the face is called blushing. It may be caused by the emotions of anger or embarrassment. The illness of rosacea is a chronic vasocongestion condition of the face that primarily affects the cheeks an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vaginal Photoplethysmograph
Vaginal photoplethysmography (VPG, VPP) is a technique using light to measure the amount of blood in the walls of the vagina. The device that is used is called a vaginal photometer. Use The device is used to try to obtain an objective measure of a woman's sexual arousal. There is an overall poor correlation (r = 0.26) between women's self-reported levels of desire and their VPG readings. Instrument The instrument used in the procedure is called vaginal photometer. The device has a clear shell, inside of which is a light source and a photocell, which senses reflected light. The use of the device is done with the assumption that the more light that is scattered back, and that the photocell senses, the more blood is in the walls of the vagina. The output of the VPG can be filtered into two types of signals, which have different properties. The direct current signal is a measure of vaginal blood volume (VBV) and reflects the total blood volume in the vaginal tissues.Hatch, J. P. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Discriminant Validity
In psychology, discriminant validity tests whether concepts or measurements that are not supposed to be related are actually unrelated. Campbell and Fiske (1959) introduced the concept of discriminant validity within their discussion on evaluating test validity. They stressed the importance of using both discriminant and Convergent validity, convergent validation techniques when assessing new tests. A successful evaluation of discriminant validity shows that a test of a concept is not highly correlated with other tests designed to measure theoretically different concepts. In showing that two scales do not correlate, it is necessary to correct for attenuation in the correlation due to measurement error. It is possible to calculate the extent to which the two scales overlap by using the following formula where r_ is correlation between x and y, r_ is the reliability of x, and r_ is the reliability of y: :\cfrac Although there is no standard value for discriminant validity, a result ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Construct Validity
Construct validity concerns how well a set of indicators represent or reflect a concept that is not directly measurable. ''Construct validation'' is the accumulation of evidence to support the interpretation of what a measure reflects.Polit DF Beck CT (2012). Nursing Research: Generating and Assessing Evidence for Nursing Practice, 9th ed. Philadelphia, USA: Wolters Klower Health, Lippincott Williams & Wilkins Modern validity theory defines construct validity as the overarching concern of validity research, subsuming all other types of validity evidence such as content validity and criterion validity. Construct validity is the appropriateness of inferences made on the basis of observations or measurements (often test scores), specifically whether a test can reasonably be considered to reflect the intended construct. Constructs are abstractions that are deliberately created by researchers in order to conceptualize the latent variable, which is correlated with scores on a given measure ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gynaecology
Gynaecology or gynecology (see spelling differences) is the area of medicine that involves the treatment of women's diseases, especially those of the reproductive organs. It is often paired with the field of obstetrics, forming the combined area of obstetrics and gynecology (OB-GYN). The term comes from Greek and means "the science of women". Its counterpart is andrology, which deals with medical issues specific to the male reproductive system. Etymology The word "gynaecology" comes from the oblique stem (γυναικ-) of the Greek word γυνή (''gyne)'' semantically attached to "woman", and ''-logia'', with the semantic attachment "study". The word gynaecology in Kurdish means "jinekolojî", separated word as "jin-ekolojî", so the Kurdish "jin" called like "gyn" and means in Kurdish "woman". History Antiquity The Kahun Gynaecological Papyrus, dated to about 1800 BC, deals with gynaecological diseases, fertility, pregnancy, contraception, etc. The text is divided into th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Obstetrics
Obstetrics is the field of study concentrated on pregnancy, childbirth and the postpartum period. As a medical specialty, obstetrics is combined with gynecology under the discipline known as obstetrics and gynecology (OB/GYN), which is a surgical field. Main areas Prenatal care Prenatal care is important in screening for various complications of pregnancy. This includes routine office visits with physical exams and routine lab tests along with telehealth care for women with low-risk pregnancies: Image:Ultrasound_image_of_a_fetus.jpg, 3D ultrasound of fetus (about 14 weeks gestational age) Image:Sucking his thumb and waving.jpg, Fetus at 17 weeks Image:3dultrasound 20 weeks.jpg, Fetus at 20 weeks First trimester Routine tests in the first trimester of pregnancy generally include: * Complete blood count * Blood type ** Rh-negative antenatal patients should receive RhoGAM at 28 weeks to prevent Rh disease. * Indirect Coombs test (AGT) to assess risk of hemolytic dis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Principal Component Analysis
Principal component analysis (PCA) is a popular technique for analyzing large datasets containing a high number of dimensions/features per observation, increasing the interpretability of data while preserving the maximum amount of information, and enabling the visualization of multidimensional data. Formally, PCA is a statistical technique for reducing the dimensionality of a dataset. This is accomplished by linearly transforming the data into a new coordinate system where (most of) the variation in the data can be described with fewer dimensions than the initial data. Many studies use the first two principal components in order to plot the data in two dimensions and to visually identify clusters of closely related data points. Principal component analysis has applications in many fields such as population genetics, microbiome studies, and atmospheric science. The principal components of a collection of points in a real coordinate space are a sequence of p unit vectors, where th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pulse
In medicine, a pulse represents the tactile arterial palpation of the cardiac cycle (heartbeat) by trained fingertips. The pulse may be palpated in any place that allows an artery to be compressed near the surface of the body, such as at the neck ( carotid artery), wrist (radial artery), at the groin (femoral artery), behind the knee (popliteal artery), near the ankle joint (posterior tibial artery), and on foot (dorsalis pedis artery). Pulse (or the count of arterial pulse per minute) is equivalent to measuring the heart rate. The heart rate can also be measured by listening to the heart beat by auscultation, traditionally using a stethoscope and counting it for a minute. The radial pulse is commonly measured using three fingers. This has a reason: the finger closest to the heart is used to occlude the pulse pressure, the middle finger is used get a crude estimate of the blood pressure, and the finger most distal to the heart (usually the ring finger) is used to nullify the eff ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photoplethysmogram
A photoplethysmogram (PPG) is an optically obtained plethysmogram that can be used to detect blood volume changes in the microvascular bed of tissue. A PPG is often obtained by using a pulse oximeter which illuminates the skin and measures changes in light absorption. A conventional pulse oximeter monitors the perfusion of blood to the dermis and subcutaneous tissue of the skin. With each cardiac cycle the heart pumps blood to the periphery. Even though this pressure pulse is somewhat damped by the time it reaches the skin, it is enough to distend the arteries and arterioles in the subcutaneous tissue. If the pulse oximeter is attached without compressing the skin, a pressure pulse can also be seen from the venous plexus, as a small secondary peak. The change in volume caused by the pressure pulse is detected by illuminating the skin with the light from a light-emitting diode (LED) and then measuring the amount of light either transmitted or reflected to a photodiode. Each c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
