Lymphopoiesis is the generation of lymphocytes, one of the five types of white blood cell. It is more formally known as lymphoid hematopoiesis. Pathosis in lymphopoiesis leads to any of various lymphoproliferative disorders, such as the lymphomas and lymphoid leukemias. Lymphocytes are considered to be of the lymphoid lineage as opposed to other lineages of blood cells such as the myeloid lineage and the erythroid lineage. Nomenclature, the system of naming things properly, is not trivial in this case because although lymphocytes are found in the bloodstream and originate in the bone marrow, they principally belong to the separate lymphatic system which interacts with the blood circulation. Lymphopoiesis is now used interchangeably with the term "lymphocytopoiesis" - the making of lymphocytes - but other sources may distinguish between the two, stating that "lymphopoiesis" additionally refers to creating lymphatic tissue, while "lymphocytopoiesis" refers only to the creation of cells in that tissue.
It is rare now for lymphopoiesis to refer to the creation of lymphatic tissues. Myelopoiesis refers to'generation of cells of the myeloid lineage' and erythropoiesis refers to'generation of cells of the erythroid lineage' etc. so parallel usage has evolved in which lymphopoiesis refers to'generation of cells of the lymphoid lineage'. Observations on research going back well over 100 years had elucidated the two great classes of WBC - Myeloid and Lymphoid - and great advances in medicine and science have resulted from these studies, it was only natural to ask where these two great classes of cells arose, after much work two cell types with some strong stem cell properties were isolated and defined - CMP, the common myeloid progenitor and CLP, the common lymphoid progenitor for mice. But science is an additive game and it was found these progenitors were not unique, further that the two great families of Myeloid and Lymphoid were not disjoint, but rather two interwoven family trees; this is more than just nomenclature, it is new science that provides challenges of complexity yet offers new vistas of bio-science and the promise of early enhancement of private and public health issues.
And it gives insight into the nature of redundancy and overlap in the immune system and hints how to use this to advantage. The partial loss of or loss of function of any white blood cell type is a serious health matter and lymphopoiesis is necessary for life. Mature lymphocytes are a critical part of the immune system that have short lives measured in days or weeks and must be continuously generated throughout life by cell division and differentiation from cells such as common lymphoid progenitors in mice. Were this system to fail, the body would be undefended from infection; the set comprising CLP cells and similar progenitors are themselves descendants of the pluripotential hemopoietic stem cell, capable of generating all of the cell types of the complete blood cell system. Despite their remarkable ability to generate the complete suite of lymphocytes, most progenitors are not true stem cells and must be continually renewed by differentiation from the pHSC stem cell. Many progenitor cells are referred to as transit cells, sometimes called transit amplifying cells, the meaning of this term being that the transit cell may found a new sub-lineage but the number of resultant cells is limited and the lineage is terminated by cells that die off or remain as cells that can no longer divide.
Examples of such cells are CFUs such as CFU-T. In mice, transplantation of a single pHSC cell can reconstitute a sub-lethally irradiated host with all these lineages of cells, including all types of lymphocytes via CLPs; this has been known for more than 40 years. Lymphopoiesis continues throughout life and so progenitor cells and their parent stem cells must always be present. In the case of mammals such as humans, lymphopoiesis begins with limited passive provision by the mother of lymphocytes and substantial immunoglobulin G that cross the placenta and enter the fetus to provide some protection against pathogens, leukocytes that come from breast milk and enter circulation via the digestive tract, it is not effective in preventing infections in the newborn. However early in gestation the developing embryo has begun its own lymphopoiesis from the fetal liver. Lymphopoiesis arises from the yolk sac; this is in contrast to the adult. There are four major types of lymphocytes, many sub-types, hundreds or thousands of lymphocyte cell types that have been identified by scientists.
All are generated by normal or abnormal lymphopoiesis except for certain artificial strains created in the laboratory by development from existing strains. Although lymphocytes are considered mature they are not inert but can and do get around the body to anywhere there is a need; this is hardly a simple topic. In his 1976 text Immunology and Cancer immunologist and Nobel Prize winner Sir Frank Macfarlane Burnet speculated that the immune system might one day be found to be as complex as the nervous system; as the production of lymphocytes is so close to the central role of the immune response it is wise
The Scottish Junior Football North Division Two was a third-tier division of the North Region of the Scottish Junior Football Association from 2003. After the withdrawal of several clubs, including Dufftown, RAF Lossiemouth and Bishopmill United, the division was left with six clubs by the end of the 2012–13 season; the decision was taken at the 2013 Regional AGM to create two parallel Division One leagues distributed geographically and split existing Division Two clubs between these. After five seasons, the previous simple three-division setup was adopted once again, with the lowest tier being the Scottish Junior Football North Second Division. North Region Division Two at Non-League Scotland
Sir George Harrison, FRS, KCH was an English barrister and civil servant. During a tenure of twenty-one years at the Treasury, he presided over the growth of a professional civil service and an increasing transfer of power from political appointees to administrators. An able young lawyer, he entered government service as register and counsel to the committee for redemption of land tax, initiated by Pitt in 1798, was called to the bar in 1800; as the legal novelties of the redemption were worked out, his duties grew more routine, freeing him for promotion in 1805. In that year, Pitt appointed him to the newly created post of Assistant Secretary of the Treasury, his duties there were both clerical and administrative, serving to reduce the routine work of the second secretary. The increasing business of the Treasury at the time necessitated the growth of a specialised bureaucracy independent of the constraints of patronage, Harrison would oversee its growth during the 21 years he spent in the post.
Upon the death of Pitt in 1806 and the formation of the Ministry of All the Talents, Harrison stood in some danger of losing his post at the Treasury. The Duke of Buckingham attempted to secure it for William Henry Fremantle, Harrison was only protected by the firmness of Grenville. Harrison and the first secretary, Vansittart were instrumental in the creation of Petty's "New Plan of Finance", for this and his assiduity in dischanging his duties, Harrison received a raise in pay from £2 000 p.a. to £2 500 in 1807. Having survived the change of ministries in 1806, Harrison weathered the fall of the coalition, became a trusted adviser to Spencer Perceval. Harrison handled the financing of the Peninsular War, became one of the two auditors of the treasury in 1807, helped to reorganise the audit office, he was admitted a Fellow of the Royal Society on 5 February 1807. His pay was raised again to £3 000 p.a. in 1809. With the accession of Liverpool as Prime Minister in 1812, his old colleague Vanisttart became Chancellor of the Exchequer, Harrison's influence and responsibility at the Treasury reached their greatest heights.
He acted as an adviser to the government in regard to the organisation of the Treasury, to the Chancellor of the Exchequer in his dealings with the Bank of England and City financial interests. He played some role in aiding the first secretary, whose duties now principally concerned patronage and politics. Harrison's extensive knowledge of the Treasury and talents for efficient administration were respected, his salary raised to £3 500 p.a. in 1815. Under his tenure, control of Treasury business passed into the hands of the bureaucrats and clerks of which he was chief. After 1809, the meetings of the Lords of the Treasury became pro forma, the Prime Minister and Chancellor ceased to attend them in 1827. In 1826, Harrison resigned the secretaryship, to be replaced as Assistant Secretary by his subordinate William Hill, his legacy at the Treasury was to have lain the foundations for the modern Civil Service. In 1823, while still at the Treasury, Harrison had been appointed auditor of the Duchy of Cornwall, in 1826 became auditor of the Duchy of Lancaster, posts which he held until his death.
His "Substance of a Report on the Laws and Jurisdiction of the Stannaries in Cornwall" was published in 1835. It is possible that this work may have been drawn on in the legal proceedings which terminated in the passage of the Cornwall Submarine Mines Act of 1858, he was appointed Knight Commander of the Royal Guelphic Order and Knight Bachelor in 1831, one of the first civil servants to receive knighthood. By his first wife, Dorothy Bunting, he had two sons.
Team Tre Berg–PostNord is a UCI Continental team founded in 2015 and based in Sweden. It participated in UCI Continental Circuits races until the end of the 2017 season. 2015 Sweden National Road Race Championship, Alexander Gingsjö Stage 3 Baltic Chain Tour, Alexander Gingsjö 2016 Sweden National Road Race Championship, Richard Larsén Sweden National Time Trail Championship, Alexander Wetterhall 2015 Sweden Road Race, Alexander Gingsjö 2016 Sweden Road Race, Richard Larsén Sweden Time Trail, Alexander Wetterhall
Seductive details are used in textbooks, lectures and other forms of educational content to make a course more interesting or interactive. Seductive details can take the form of text, illustrations, sounds or music and are by definition: interesting and not directed toward the learning objectives of a lesson. John Dewey, in 1913, first referred to this as “fictitious inducements to attention.” While illustrated text can enhance comprehension, illustrations that are not relevant can lead to poor learning outcomes. Since the late 1980s, many studies in the field of educational psychology have shown that the addition of seductive details results in poorer retention of information and transfer of learning. Thalheimer conducted a meta-analysis that found, overall, a negative impact for the inclusion of seductive details such as text, photos or illustrations, sounds or music in learning content; this reduction to learning is called the seductive details effect. There have been many criticisms of this theory.
Critics cite unconvincing and contradictory evidence to argue that seductive details do not always impede understanding and that seductive details can sometimes be motivating for learners. Most studies are conducted through experiments that compare the learning results between two scenarios: an explanation with seductive details and an explanation with no seductive details; the explanation format can vary in form from text-based, web-based or presentation style. The seductive details in these experiments varies from extraneous details to irrelevant images or irrelevant video. Learning outcomes of participants are determined through a variety of tests that include both recall abilities and problem-solving abilities; this is known as transfer performance. Early research showed that adding seductive details did not have the intended effect of improving learning. Adding interesting but unimportant sentences to expository texts hindered the learning of the main points of the text and learners would remember the seductive details better than the main text.
An example of a seductive detail in a training context might be a training class that includes cartoons on slides containing tips for effective supervision. Although not relevant to the topic, the cartoons are designed to make the training material more interesting, but the results of multiple studies suggest that their inclusion will harm recall from the primary training content. Harp and Mayer conducted an experiment using a lesson about lightning strikes; the effect of lightning strikes on airplanes was added as a seductive detail. In six out of six experiments, learners who studied the base lesson without the seductive details about the strikes on airplanes demonstrated they were three times more to recall the structurally important details, they performed much better on a problem-solving task than learners whose lessons included the seductive details. Harper and Mayer suggested seductive details do their damage when learners are consolidating and organizing new information by forming knowledge structures ill-suited for recall.
Researchers focus on various aspects of cognitive theory to explain the seductive details effect. Seductive details impose an extraneous cognitive load during learning by enticing students to spend their limited resources in processing materials that distract from, or disrupt, the construction of a coherent mental model in the learning process. Most studies use seductive details in science text to demonstrate the extraneous cognitive load. However, there are contrasting studies done with non-scientific texts that did not produce the same results; these results may suggest that seductive details can only interfere with learning within a high load learning process that requires managing the available cognitive resources. In learning situations that are associated with low working memory activity, seductive details did not have a detrimental effect, they can lead to higher performance because there are the required cognitive resources available for the motivating function. Jaeger and Wiley, in 2015, looked at readers' ability to monitor their own comprehension.
Their study used a science text as the base of a lesson and decorative images as the seductive details. They found that readers were less able to monitor their own comprehension of the text when the text was sprinkled with decorative images. A 1998 study by Harp and Mayer determined that it was that the seductive details effect created an inappropriate diversion for the learner "by activating an inappropriate base of prior knowledge in the learner". Further, they found that when seductive details were placed at the beginning of a lesson, a learner's performance would be hindered. However, when seductive details were put at the end of a lesson, a student's performance was similar to a student who had not experienced seductive details in their lesson. A study by Sanchez and Wiley showed that seductive details caused poor learning outcomes because they take up some of the limited space in working memory; the experiment compared people's ability to control their attention to scientific text that contained either seductive images, relevant images, or no images.
The study showed that people with low working memory capacity were vulnerable to the seductive details effect. Sanchez and Wiley did an experiment where eye-tracking was monitored to evaluate how people were reading the same seductively illustrated scientific text; the results showed that people with low working memory looked at the seductive illustrations more and for longer than those with high working memory capacity. It could be argued that differences in performance between high- and low- work