Medical diagnosis
Medical diagnosis is the process of determining which disease or condition explains a person's symptoms and signs. It is most referred to as diagnosis with the medical context being implicit; the information required for diagnosis is collected from a history and physical examination of the person seeking medical care. One or more diagnostic procedures, such as diagnostic tests, are done during the process. Sometimes posthumous diagnosis is considered a kind of medical diagnosis. Diagnosis is challenging, because many signs and symptoms are nonspecific. For example, redness of the skin, by itself, is a sign of many disorders and thus does not tell the healthcare professional what is wrong, thus differential diagnosis, in which several possible explanations are compared and contrasted, must be performed. This involves the correlation of various pieces of information followed by the recognition and differentiation of patterns; the process is made easy by a sign or symptom, pathognomonic. Diagnosis is a major component of the procedure of a doctor's visit.
From the point of view of statistics, the diagnostic procedure involves classification tests. The first recorded examples of medical diagnosis are found in the writings of Imhotep in ancient Egypt. A Babylonian medical textbook, the Diagnostic Handbook written by Esagil-kin-apli, introduced the use of empiricism and rationality in the diagnosis of an illness or disease. Traditional Chinese Medicine, as described in the Yellow Emperor's Inner Canon or Huangdi Neijing, specified four diagnostic methods: inspection, auscultation-olfaction and palpation. Hippocrates was known to make diagnoses by smelling their sweat. A diagnosis, in the sense of diagnostic procedure, can be regarded as an attempt at classification of an individual's condition into separate and distinct categories that allow medical decisions about treatment and prognosis to be made. Subsequently, a diagnostic opinion is described in terms of a disease or other condition, but in the case of a wrong diagnosis, the individual's actual disease or condition is not the same as the individual's diagnosis.
A diagnostic procedure may be performed by various health care professionals such as a physician, physical therapist, healthcare scientist, dentist, nurse practitioner, or physician assistant. This article uses diagnostician as any of these person categories. A diagnostic procedure does not involve elucidation of the etiology of the diseases or conditions of interest, that is, what caused the disease or condition; such elucidation can be useful to optimize treatment, further specify the prognosis or prevent recurrence of the disease or condition in the future. The initial task is to detect a medical indication to perform a diagnostic procedure. Indications include: Detection of any deviation from what is known to be normal, such as can be described in terms of, for example, physiology, pathology and human homeostasis. Knowledge of what is normal and measuring of the patient's current condition against those norms can assist in determining the patient's particular departure from homeostasis and the degree of departure, which in turn can assist in quantifying the indication for further diagnostic processing.
A complaint expressed by a patient. The fact that a patient has sought a diagnostician can itself be an indication to perform a diagnostic procedure. For example, in a doctor's visit, the physician may start performing a diagnostic procedure by watching the gait of the patient from the waiting room to the doctor's office before she or he has started to present any complaints. During an ongoing diagnostic procedure, there can be an indication to perform another, diagnostic procedure for another concomitant, disease or condition; this may occur as a result of an incidental finding of a sign unrelated to the parameter of interest, such as can occur in comprehensive tests such as radiological studies like magnetic resonance imaging or blood test panels that include blood tests that are not relevant for the ongoing diagnosis. General components which are present in a diagnostic procedure in most of the various available methods include: Complementing the given information with further data gathering, which may include questions of the medical history, physical examination and various diagnostic tests.
A diagnostic test is any kind of medical test performed to aid in the diagnosis or detection of disease. Diagnostic tests can be used to provide prognostic information on people with established disease. Processing of the answers, findings or other results. Consultations with other providers and specialists in the field may be sought. There are a number of methods or techniques that can be used in a diagnostic procedure, including performing a differential diagnosis or following medical algorithms. In reality, a diagnostic procedure may involve components of multiple methods; the method of differential diagnosis is based on finding as many candidate diseases or conditions as possible that can cause the signs or symptoms, followed by a process of elimination or at least of rendering the entries more or less probable by further medical tests and other processing until, aiming to reach the point where only one candidate disease or condit
Soft tissue
In anatomy, soft tissue includes the tissues that connect, support, or surround other structures and organs of the body, not being hard tissue such as bone. Soft tissue includes tendons, fascia, fibrous tissues and synovial membranes, muscles and blood vessels, it is sometimes defined by. Soft tissue has been defined as "nonepithelial, extraskeletal mesenchyme exclusive of the reticuloendothelial system and glia"; the characteristic substances inside the extracellular matrix of this kind of tissue are the collagen and ground substance. The soft tissue is hydrated because of the ground substance; the fibroblasts are the most common cell responsible for the production of soft tissues' fibers and ground substance. Variations of fibroblasts, like chondroblasts, may produce these substances. At small strains, elastin stores most of the strain energy; the collagen fibers are comparatively inextensible and are loose. With increasing tissue deformation the collagen is stretched in the direction of deformation.
When taut, these fibers produce a strong growth in tissue stiffness. The composite behavior is analogous to a nylon stocking, whose rubber band does the role of elastin as the nylon does the role of collagen. In soft tissues, the collagen protects the tissues from injury. Human soft tissue is deformable, its mechanical properties vary from one person to another. Impact testing results showed that the stiffness and the damping resistance of a test subject’s tissue are correlated with the mass and size of the striking object; such properties may be useful for forensics investigation. When a solid object impacts a human soft tissue, the energy of the impact will be absorbed by the tissues to reduce the effect of the impact or the pain level. Soft tissues have the potential to undergo large deformations and still return to the initial configuration when unloaded, i.e. they are hyperelastic materials, their stress-strain curve is nonlinear. The soft tissues are viscoelastic and anisotropic; some viscoelastic properties observable in soft tissues are: relaxation and hysteresis.
In order to describe the mechanical response of soft tissues, several methods have been used. These methods include: hyperelastic macroscopic models based on strain energy, mathematical fits where nonlinear constitutive equations are used, structurally based models where the response of a linear elastic material is modified by its geometric characteristics. Though soft tissues have viscoelastic properties, i.e. stress as function of strain rate, it can be approximated by a hyperelastic model after precondition to a load pattern. After some cycles of loading and unloading the material, the mechanical response becomes independent of strain rate. S = S → S = S Despite the independence of strain rate, preconditioned soft tissues still present hysteresis, so the mechanical response can be modeled as hyperelastic with different material constants at loading and unloading. By this method the elasticity theory is used to model an inelastic material. Fung has called this model as pseudoelastic to point out that the material is not elastic.
In physiological state soft tissues present residual stress that may be released when the tissue is excised. Physiologists and histologists must be aware of this fact to avoid mistakes when analyzing excised tissues; this retraction causes a visual artifact. Fung developed a constitutive equation for preconditioned soft tissues, W = 1 2 with q = a i j k l E i j E k l Q = b i j k l E i j E k l quadratic forms of Green-Lagrange strains E i j and a i j k l, b i j k l and c material constants. W is the strain energy function per volume unit, the mechanical strain energy for a given temperature; the Fung-model, simplified with isotropic hypothesis. This written in respect of the principal stretches: W = 1 2 [ a ( λ 1 2 + λ 2 2 + λ 3
Doctor of Medicine
A Doctor of Medicine is a medical degree, the meaning of which varies between different jurisdictions. In the United States and other countries, the MD denotes a professional graduate degree awarded upon graduation from medical school. In the United Kingdom and other countries, the MD is a research doctorate, higher doctorate, honorary doctorate or applied clinical degree restricted to those who hold a professional degree in medicine. In 1703, the University of Glasgow's first medical graduate, Samuel Benion, was issued with the academic degree of Doctor of Medicine. University medical education in England culminated with the MB qualification, in Scotland the MD, until in the mid-19th century the public bodies who regulated medical practice at the time required practitioners in Scotland as well as England to hold the dual Bachelor of Medicine and Bachelor of Surgery degrees. North American medical schools switched to the tradition of the ancient universities of Scotland and began granting the MoD title rather than the MB beginning in the late 18th century.
The Columbia University College of Physicians and Surgeons in New York was the first American university to grant the MD degree instead of the MB. Early medical schools in North America that granted the Doctor of Medicine degrees were Columbia, Harvard, McGill; these first few North American medical schools that were established were founded by physicians and surgeons, trained in England and Scotland. A feminine form, "Doctress of Medicine" or Medicinae Doctrix, was used by the New England Female Medical College in Boston in the 1860s. In most countries having a Doctor of Medicine degree does not mean that the individual will be allowed to practice medicine. A doctor must go through a residency for at least four years and take some form of licensing examination in their jurisdiction. In Afghanistan, medical education begins after high school. No pre-medicine courses or bachelor's degree is required. Eligibility is determined through the rank applicants obtain in the public university entrance exam held every year throughout the country.
Entry to medical school is competitive, only students with the highest ranks are accepted into medical programs. The primary medical degree is completed in 7 years. According to the new medical curriculum, during the 12th semester, medical students must complete research on a medical topic and provide a thesis as part of their training. Medical graduates are awarded a certificate in general medicine, regarded "MD" and validated by the "Ministry of Higher Education of Afghanistan". All physicians are to obtain licensing and a medical council registration number from the "Ministry of Public Health" before they begin to practice, they may subsequently specialize in a specific medical field at medical schools offering the necessary qualifications. After graduation, students may complete residency; the MD specification: Before the civil wars in Afghanistan, medical education used to be taught by foreign professors or Afghan professors who studied medical education abroad. The Kabul medical institute certified the students as "Master of Medicine".
After the civil wars, medical education has changed, the MD certification has been reduced to "Medicine Bachelor". In Argentina, the First Degree of Physician or Physician Diplomate is equivalent to the North American MD Degree with six years of intensive studies followed by three or four years of residency as a major specialty in a particular empiric field, consisting of internships, social services and sporadic research. Only by holding a Medical Title can the postgraduate student apply for the Doctor degree through a Doctorate in Medicine program approved by the National Commission for University Evaluation and Accreditation. Australian medical schools have followed the British tradition by conferring the degrees of Bachelor of Medicine and Bachelor of Surgery to its graduates whilst reserving the title of Doctor of Medicine for their research training degree, analogous to the PhD, or for their honorary doctorates. Although the majority of Australian MBBS degrees have been graduate programs since the 1990s, under the previous Australian Qualifications Framework they remained categorized as Level 7 Bachelor's degrees together with other undergraduate programs.
The latest version of the AQF includes the new category of Level 9 Master's degrees which permits the use of the term'Doctor' in the styling of the degree title of relevant professional programs. As a result, various Australian medical schools have replaced their MBBS degrees with the MD to resolve the previous anomalous nomenclature. With the introduction of the Master's level MD, universities have renamed their previous medical research doctorates; the University of Melbourne was the first to introduce the MD in 2011 as a basic medical degree, has renamed its research degree to Doctor of Medical Science. In French-speaking Belgium, the medical degree awarded after six years of study is "Docteur en Médecine". Physicians would have to register with the Ordre des Medicins to practice medicine in the country. At the end of the six-year medical programs from Bulgarian medical schools, medical students are awarded the academic degree Master in Medicine and the professional title Physician - Doctor of Medicine.
After 6 years of general medical education, all students will graduate with
JAK-STAT signaling pathway
The JAK-STAT signalling pathway is a chain of interactions between proteins in a cell, is involved in processes such as immunity, cell division, cell death and tumour formation. The pathway communicates information from chemical signals outside of a cell to the cell nucleus, resulting in the activation of genes through a process called transcription. There are three key parts of JAK-STAT signalling: Janus kinases, Signal Transducer and Activator of Transcription proteins, receptors. Disrupted JAK-STAT signalling may lead to a variety of diseases, such as skin conditions and disorders affecting the immune system. Main articles: JAKs and STATs There are 4 JAK proteins: JAK1, JAK2, JAK3 and TYK2. JAKs contains an SH2-related domain, a kinase domain and a pseudokinase domain; the kinase domain is vital for JAK activity. There are 7 STAT proteins: STAT1, STAT2, STAT3, STAT4, STAT5A, STAT5B and STAT6. STAT proteins contain many different domains, each with a different function, of which the most conserved region is the SH2 domain.
The SH2 domain is formed of 2 α-helices and a β-sheet and is formed from residues 575-680. STATs have transcriptional activation domains, which are less conserved and are located at the C-terminus. In addition, STATs contain: tyrosine activation, amino-terminal, coiled-coil and DNA-binding domains; the binding of various ligands cytokines, such as interferons and interleukins, to cell-surface receptors, causes the receptors to dimerize, which brings the receptor-associated JAKs into close proximity. The JAKs phosphorylate each other on tyrosine residues located in regions called activation loops, through a process called transphosphorylation, which increases the activity of their kinase domains; the activated JAKs phosphorylate tyrosine residues on the receptor, creating binding sites for proteins possessing SH2 domains. STATs bind to the phosphorylated tyrosines on the receptor using their SH2 domains, they are tyrosine-phosphorylated by JAKs, causing the STATs to dissociate from the receptor.
These activated STATs form hetero- or homodimers, where the SH2 domain of each STAT binds the phosphorylated tyrosine of the opposite STAT, the dimer translocates to the cell nucleus to induce transcription of target genes. STATs may be tyrosine-phosphorylated directly by receptor tyrosine kinases - but since most receptors lack built-in kinase activity, JAKs are required for signalling. To move from the cytosol to the nucleus, STAT dimers have to pass through nuclear pore complexes, which are protein complexes present along the nuclear envelope that control the flow of substances in and out of the nucleus. To enable STATs to move into the nucleus, an amino acid sequence on STATs, called the nuclear localization signal, is bound by proteins called importins. Once the STAT dimer enters the nucleus, a protein called Ran binds to the importins, releasing them from the STAT dimer; the STAT dimer is free in the nucleus. Specific STATs appear to bind to specific importin proteins. For example, STAT3 proteins can enter the nucleus by binding to importin α3 and importin α6.
On the other hand, STAT1 and STAT2 bind to importin α5. Studies indicate that STAT2 requires a protein called interferon regulatory factor 9 to enter the nucleus. Not as much is known about nuclear entrance of other STATs, but it has been suggested that a sequence of amino acids in the DNA-binding domain of STAT4 might allow nuclear import. In addition, STAT3, STAT5 and STAT6 can enter the nucleus if they are not phosphorylated at tyrosine residues. After STATs are made by protein biosynthesis, they have non-protein molecules attached to them, called post-translational modifications. One example of this is tyrosine phosphorylation, but STATs experience other modifications, which may affect STAT behaviour in JAK-STAT signalling; these modifications include: methylation and serine phosphorylation. Methylation. STAT3 can be dimethylated on a lysine residue, at position 140, it suggested that this could reduce STAT3 activity. There is debate as to whether STAT1 is methylated on an arginine residue, what the function of this methylation could be.
Acetylation. STAT1, STAT2, STAT3, STAT5 and STAT6 have been shown to be acetylated. STAT1 may have an acetyl group attached to lysines at positions 410 and 413, as a result, STAT1 can promote the transcription of apoptotic genes - triggering cell death. STAT2 acetylation is important for interactions with other STATs, for the transcription of anti-viral genes. Acetylation of STAT3 has been suggested to be important for its dimerization, DNA-binding and gene-transcribing ability, IL-6 JAK-STAT pathways that use STAT3 require acetylation for transcription of IL-6 response genes. STAT5 acetylation on lysines at positions 694 and 701 is important for effective STAT dimerization in prolactin signalling. Adding acetyl groups to STAT6 is suggested to be essential for gene transcription in some forms of IL-4 signalling, but not all the amino acids which are acetylated on STAT6 are known. Serine phosphorylation - Most of the seven STATs undergo serine phosphorylation. Serine phosphorylation of STATs has been shown to reduce gene transcription.
It is required for the transcription of some target genes of the cytokines IL-6 and IFN- γ. It has been proposed that phosp
Hospital
A hospital is a health care institution providing patient treatment with specialized medical and nursing staff and medical equipment. The best-known type of hospital is the general hospital, which has an emergency department to treat urgent health problems ranging from fire and accident victims to a sudden illness. A district hospital is the major health care facility in its region, with a large number of beds for intensive care and additional beds for patients who need long-term care. Specialized hospitals include trauma centers, rehabilitation hospitals, children's hospitals, seniors' hospitals, hospitals for dealing with specific medical needs such as psychiatric treatment and certain disease categories. Specialized hospitals can help reduce health care costs compared to general hospitals. Hospitals are classified as general, specialty, or government depending on the sources of income received. A teaching hospital combines assistance to people with teaching to medical nurses; the medical facility smaller than a hospital is called a clinic.
Hospitals have a range of departments and specialist units such as cardiology. Some hospitals have outpatient departments and some have chronic treatment units. Common support units include a pharmacy and radiology. Hospitals are funded by the public sector, health organisations, health insurance companies, or charities, including direct charitable donations. Hospitals were founded and funded by religious orders, or by charitable individuals and leaders. Hospitals are staffed by professional physicians, surgeons and allied health practitioners, whereas in the past, this work was performed by the members of founding religious orders or by volunteers. However, there are various Catholic religious orders, such as the Alexians and the Bon Secours Sisters that still focus on hospital ministry in the late 1990s, as well as several other Christian denominations, including the Methodists and Lutherans, which run hospitals. In accordance with the original meaning of the word, hospitals were "places of hospitality", this meaning is still preserved in the names of some institutions such as the Royal Hospital Chelsea, established in 1681 as a retirement and nursing home for veteran soldiers.
During the Middle Ages, hospitals served different functions from modern institutions. Middle Ages hospitals were hostels for pilgrims, or hospital schools; the word "hospital" comes from the Latin hospes, signifying a foreigner, hence a guest. Another noun derived from this, hospitium came to signify hospitality, the relation between guest and shelterer, hospitality and hospitable reception. By metonymy the Latin word came to mean a guest-chamber, guest's lodging, an inn. Hospes is thus the root for the English words host hospitality, hospice and hotel; the latter modern word derives from Latin via the ancient French romance word hostel, which developed a silent s, which letter was removed from the word, the loss of, signified by a circumflex in the modern French word hôtel. The German word'Spital' shares similar roots; the grammar of the word differs depending on the dialect. In the United States, hospital requires an article; some patients go to a hospital just for diagnosis, treatment, or therapy and leave without staying overnight.
Hospitals are distinguished from other types of medical facilities by their ability to admit and care for inpatients whilst the others, which are smaller, are described as clinics. The best-known type of hospital is the general hospital known as an acute-care hospital; these facilities handle many kinds of disease and injury, have an emergency department or trauma center to deal with immediate and urgent threats to health. Larger cities may have several hospitals of facilities; some hospitals in the United States and Canada, have their own ambulance service. A district hospital is the major health care facility in its region, with large numbers of beds for intensive care, critical care, long-term care. In California, "district hospital" refers to a class of healthcare facility created shortly after World War II to address a shortage of hospital beds in many local communities. Today, district hospitals are the sole public hospitals in 19 of California's counties, are the sole locally-accessible hospital within nine additional counties in which one or more other hospitals are present at substantial distance from a local community.
Twenty-eight of California's rural hospitals and 20 of its critical-access hospitals are district hospitals. They are formed by local municipalities, have boards that are individually elected by their local communities, exist to serve local needs, they are a important provider of healthcare to uninsured patients and patients with Medi-Cal. In 2012, district hospitals provided $54 million in uncompensated care in California. Types of specialised hospitals incl
Immune system
The immune system is a host defense system comprising many biological structures and processes within an organism that protects against disease. To function properly, an immune system must detect a wide variety of agents, known as pathogens, from viruses to parasitic worms, distinguish them from the organism's own healthy tissue. In many species, the immune system can be classified into subsystems, such as the innate immune system versus the adaptive immune system, or humoral immunity versus cell-mediated immunity. In humans, the blood–brain barrier, blood–cerebrospinal fluid barrier, similar fluid–brain barriers separate the peripheral immune system from the neuroimmune system, which protects the brain. Pathogens can evolve and adapt, thereby avoid detection and neutralization by the immune system. Simple unicellular organisms such as bacteria possess a rudimentary immune system in the form of enzymes that protect against bacteriophage infections. Other basic immune mechanisms evolved in ancient eukaryotes and remain in their modern descendants, such as plants and invertebrates.
These mechanisms include phagocytosis, antimicrobial peptides called defensins, the complement system. Jawed vertebrates, including humans, have more sophisticated defense mechanisms, including the ability to adapt over time to recognize specific pathogens more efficiently. Adaptive immunity creates immunological memory after an initial response to a specific pathogen, leading to an enhanced response to subsequent encounters with that same pathogen; this process of acquired immunity is the basis of vaccination. Disorders of the immune system can result in inflammatory diseases and cancer. Immunodeficiency occurs when the immune system is less active than normal, resulting in recurring and life-threatening infections. In humans, immunodeficiency can either be the result of a genetic disease such as severe combined immunodeficiency, acquired conditions such as HIV/AIDS, or the use of immunosuppressive medication. In contrast, autoimmunity results from a hyperactive immune system attacking normal tissues as if they were foreign organisms.
Common autoimmune diseases include Hashimoto's thyroiditis, rheumatoid arthritis, diabetes mellitus type 1, systemic lupus erythematosus. Immunology covers the study of all aspects of the immune system; the immune system protects organisms from infection with layered defenses of increasing specificity. In simple terms, physical barriers prevent pathogens such as bacteria and viruses from entering the organism. If a pathogen breaches these barriers, the innate immune system provides an immediate, but non-specific response. Innate immune systems are found in all animals. If pathogens evade the innate response, vertebrates possess a second layer of protection, the adaptive immune system, activated by the innate response. Here, the immune system adapts its response during an infection to improve its recognition of the pathogen; this improved response is retained after the pathogen has been eliminated, in the form of an immunological memory, allows the adaptive immune system to mount faster and stronger attacks each time this pathogen is encountered.
Both innate and adaptive immunity depend on the ability of the immune system to distinguish between self and non-self molecules. In immunology, self molecules are those components of an organism's body that can be distinguished from foreign substances by the immune system. Conversely, non-self molecules are those recognized as foreign molecules. One class of non-self molecules are called antigens and are defined as substances that bind to specific immune receptors and elicit an immune response. Newborn infants have no prior exposure to microbes and are vulnerable to infection. Several layers of passive protection are provided by the mother. During pregnancy, a particular type of antibody, called IgG, is transported from mother to baby directly through the placenta, so human babies have high levels of antibodies at birth, with the same range of antigen specificities as their mother. Breast milk or colostrum contains antibodies that are transferred to the gut of the infant and protect against bacterial infections until the newborn can synthesize its own antibodies.
This is passive immunity because the fetus does not make any memory cells or antibodies—it only borrows them. This passive immunity is short-term, lasting from a few days up to several months. In medicine, protective passive immunity can be transferred artificially from one individual to another via antibody-rich serum. Microorganisms or toxins that enter an organism encounter the cells and mechanisms of the innate immune system; the innate response is triggered when microbes are identified by pattern recognition receptors, which recognize components that are conserved among broad groups of microorganisms, or when damaged, injured or stressed cells send out alarm signals, many of which are recognized by the same receptors as those that recognize pathogens. Innate immune defenses are non-specific, meaning these systems respond to pathogens in a generic way; this system does not confer long-lasting immunity against a pathogen. The innate immune system is the dominant system of host defense in most organisms.
Cells in innate immune system recognizes use pattern recognition receptors to recognize molecular structures that are produced by microbial pathogens. PRRs are germline-encoded host sensors, they are proteins expressed by cells of the innate immune system, such as dendritic cells, macrophages, m
X-ray
X-rays make up X-radiation, a form of electromagnetic radiation. Most X-rays have a wavelength ranging from 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 100 eV to 100 keV. X-ray wavelengths are shorter than those of UV rays and longer than those of gamma rays. In many languages, X-radiation is referred to with terms meaning Röntgen radiation, after the German scientist Wilhelm Röntgen who discovered these on November 8, 1895, credited as its discoverer, who named it X-radiation to signify an unknown type of radiation. Spelling of X-ray in the English language includes the variants x-ray, X ray. Before their discovery in 1895 X-rays were just a type of unidentified radiation emanating from experimental discharge tubes, they were noticed by scientists investigating cathode rays produced by such tubes, which are energetic electron beams that were first observed in 1869. Many of the early Crookes tubes undoubtedly radiated X-rays, because early researchers noticed effects that were attributable to them, as detailed below.
Crookes tubes created free electrons by ionization of the residual air in the tube by a high DC voltage of anywhere between a few kilovolts and 100 kV. This voltage accelerated the electrons coming from the cathode to a high enough velocity that they created X-rays when they struck the anode or the glass wall of the tube; the earliest experimenter thought to have produced. In 1785 he presented a paper to the Royal Society of London describing the effects of passing electrical currents through a evacuated glass tube, producing a glow created by X-rays; this work was further explored by his assistant Michael Faraday. When Stanford University physics professor Fernando Sanford created his "electric photography" he unknowingly generated and detected X-rays. From 1886 to 1888 he had studied in the Hermann Helmholtz laboratory in Berlin, where he became familiar with the cathode rays generated in vacuum tubes when a voltage was applied across separate electrodes, as studied by Heinrich Hertz and Philipp Lenard.
His letter of January 6, 1893 to The Physical Review was duly published and an article entitled Without Lens or Light, Photographs Taken With Plate and Object in Darkness appeared in the San Francisco Examiner. Starting in 1888, Philipp Lenard, a student of Heinrich Hertz, conducted experiments to see whether cathode rays could pass out of the Crookes tube into the air, he built a Crookes tube with a "window" in the end made of thin aluminum, facing the cathode so the cathode rays would strike it. He found that something came through, that would cause fluorescence, he measured the penetrating power of these rays through various materials. It has been suggested that at least some of these "Lenard rays" were X-rays. In 1889 Ukrainian-born Ivan Pulyui, a lecturer in experimental physics at the Prague Polytechnic who since 1877 had been constructing various designs of gas-filled tubes to investigate their properties, published a paper on how sealed photographic plates became dark when exposed to the emanations from the tubes.
Hermann von Helmholtz formulated mathematical equations for X-rays. He postulated a dispersion theory before Röntgen made his announcement, it was formed on the basis of the electromagnetic theory of light. However, he did not work with actual X-rays. In 1894 Nikola Tesla noticed damaged film in his lab that seemed to be associated with Crookes tube experiments and began investigating this radiant energy of "invisible" kinds. After Röntgen identified the X-ray, Tesla began making X-ray images of his own using high voltages and tubes of his own design, as well as Crookes tubes. On November 8, 1895, German physics professor Wilhelm Röntgen stumbled on X-rays while experimenting with Lenard tubes and Crookes tubes and began studying them, he wrote an initial report "On a new kind of ray: A preliminary communication" and on December 28, 1895 submitted it to Würzburg's Physical-Medical Society journal. This was the first paper written on X-rays. Röntgen referred to the radiation as "X"; the name stuck.
They are still referred to as such in many languages, including German, Danish, Swedish, Estonian, Japanese, Georgian and Norwegian. Röntgen received the first Nobel Prize in Physics for his discovery. There are conflicting accounts of his discovery because Röntgen had his lab notes burned after his death, but this is a reconstruction by his biographers: Röntgen was investigating cathode rays from a Crookes tube which he had wrapped in black cardboard so that the visible light from the tube would not interfere, using a fluorescent screen painted with barium platinocyanide, he noticed a faint green glow from the screen, about 1 meter away. Röntgen realized some invisible rays coming from the tube were passing through the cardboard to make the screen glow, he found they could pass through books and papers on his desk. Röntgen threw himself into investigating these unknown rays systematically. Two months after his initial discovery, he published his paper. Röntgen discovered their medical use when he made a picture of his wife's hand on a photographic plate formed due to X-rays.
The photograph of his wife's hand was the first photograph of a human body part using X-rays. When she saw the picture, she said "I have seen my death."The discovery of X-rays stimul
