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Pulse Forming Network
A pulse forming network (PFN) is an electric circuit that accumulates electrical energy over a comparatively long time, then releases the stored energy in the form of a relatively square pulse of comparatively brief duration for various pulsed power applications. In a PFN, energy storage components such as capacitors, inductors or transmission lines are charged by means of a high voltage power source, then rapidly discharged into a load via a high voltage switch, such as a spark gap or hydrogen thyratron. Repetition rates range from single pulses to about 104 per second. PFNs are used to produce precise nanosecond-length pulses of electricity to power devices such as klystron or magnetron tube oscillators in radar sets, pulsed lasers, particle accelerators, flashtubes, and high voltage utility test equipment. Much high energy research equipment is operated in a pulsed mode, both to keep heat dissipation down and because high energy physics often occurs at short time scales, so large PFNs are widely used in high energy research. They have been used to produce nanosecond length pulses with voltages of up to 106 - 107 volts and currents up to 106 amps, with peak power in the terawatt range, similar to lightning bolts.
  • 1.4K
  • 01 Nov 2022
Topic Review
Developmental Needs Meeting Strategy
The Developmental Needs Meeting Strategy (DNMS) is a psychotherapy approach developed by Shirley Jean Schmidt, MA, LPC. It is designed to treat adults with psychological trauma wounds (such as those inflicted by verbal, physical, and sexual abuse) and with attachment wounds (such as those inflicted by parental rejection, neglect, and enmeshment). The DNMS is an ego state therapy based on the assumption that the degree to which developmental needs were not adequately met is the degree to which a client may be stuck in childhood. This model aims to identify ego states that are stuck in the past and help them get unstuck by remediating those unmet developmental needs. The processing starts with the DNMS therapist guiding a patient to mobilize three internal Resource ego states: a Nurturing Adult Self, a Protective Adult Self, and a Spiritual Core Self. The therapist then guides these three Resources to gently help wounded child ego states get unstuck from the past by meeting their unmet developmental needs, helping them process through painful emotions, and by establishing an emotional bond. The relationship wounded child parts have with these Resources is considered the primary agent for change. Alternating bilateral stimulation (made popular by EMDR therapy) is applied at key points in the protocol to enhance the process. The DNMS focuses special attention on healing maladaptive introjects (wounded ego states that mimic abusive, neglectful, or dysfunctional caregivers. The model assumes that these ego states cause the most trouble for clients, so helping them heal may result in a significant benefit – leading to a decrease in unwanted behaviors, beliefs, and emotions.
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  • 01 Nov 2022
Topic Review
Sulfate-Reducing Microorganisms
Sulfate-reducing microorganisms (SRM) or sulfate-reducing prokaryotes (SRP) are a group composed of sulfate-reducing bacteria (SRB) and sulfate-reducing archaea (SRA), both of which can perform anaerobic respiration utilizing sulfate (SO42–) as terminal electron acceptor, reducing it to hydrogen sulfide (H2S). Therefore, these sulfidogenic microorganisms "breathe" sulfate rather than molecular oxygen (O2), which is the terminal electron acceptor reduced to water (H2O) in aerobic respiration. Most sulfate-reducing microorganisms can also reduce some other oxidized inorganic sulfur compounds, such as sulfite (SO32–), dithionite (S2O42–), thiosulfate (S2O32–), trithionate (S3O62–), tetrathionate (S4O62−), elemental sulfur (S8), and polysulfides (Sn2−). Depending on the context, "sulfate-reducing microorganisms" can be used in a broader sense (including all species that can reduce any of these sulfur compounds) or in a narrower sense (including only species that reduce sulfate, and excluding strict thiosulfate and sulfur reducers, for example). Sulfate-reducing microorganisms can be traced back to 3.5 billion years ago and are considered to be among the oldest forms of microbes, having contributed to the sulfur cycle soon after life emerged on Earth. Many organisms reduce small amounts of sulfates in order to synthesize sulfur-containing cell components; this is known as assimilatory sulfate reduction. By contrast, the sulfate-reducing microorganisms considered here reduce sulfate in large amounts to obtain energy and expel the resulting sulfide as waste; this is known as dissimilatory sulfate reduction. They use sulfate as the terminal electron acceptor of their electron transport chain. Most of them are anaerobes; however, there are examples of sulfate-reducing microorganisms that are tolerant of oxygen, and some of them can even perform aerobic respiration. No growth is observed when oxygen is used as the electron acceptor. In addition, there are sulfate-reducing microorganisms that can also reduce other electron acceptors, such as fumarate, nitrate (NO3−), nitrite (NO2−), ferric iron [Fe(III)], and dimethyl sulfoxide. In terms of electron donor, this group contains both organotrophs and lithotrophs. The organotrophs oxidize organic compounds, such as carbohydrates, organic acids (e.g., formate, lactate, acetate, propionate, and butyrate), alcohols (methanol and ethanol), aliphatic hydrocarbons (including methane), and aromatic hydrocarbons (benzene, toluene, ethylbenzene, and xylene). The lithotrophs oxidize molecular hydrogen (H2), for which they compete with methanogens and acetogens in anaerobic conditions. Some sulfate-reducing microorganisms can directly utilize metallic iron [Fe(0)] as electron donor, oxidizing it to ferrous iron [Fe(II)].
  • 6.3K
  • 04 Nov 2022
Topic Review
Microsoft Store (Digital)
Microsoft Store (formerly known as Windows Store) is a digital distribution platform owned by Microsoft. It started as an app store for Windows 8 and Windows Server 2012 as the primary means of distributing Universal Windows Platform (UWP) apps. With Windows 10, Microsoft merged its other distribution platforms (Windows Marketplace, Windows Phone Store, Xbox Music, Xbox Video, Xbox Store, and a web storefront also known as "Microsoft Store") into Microsoft Store, making it a unified distribution point for apps, console games, and digital videos. Digital music was included until the end of 2017, and E-books were included until 2019. Some content is available free of charge from the store. In 2015, over 669,000 apps were available on the store. Categories containing the largest number of apps are "Books and Reference", "Education", "Entertainment", and "Games". The majority of the app developers have one app. As with other similar platforms, such as the Google Play and Mac App Store, Microsoft Store is curated, and apps must be certified for compatibility and content. In addition to the user-facing Microsoft Store client, the store has a developer portal with which developers can interact. Microsoft takes 30% of the sale price for apps. Prior to January 1, 2015, this cut was reduced to 20% after the developer's profits reached $25,000.
  • 2.1K
  • 01 Nov 2022
Topic Review
Clip (Command)
The clipboard is a buffer that some operating systems provide for short-term storage and transfer within and between application programs. The clipboard is usually temporary and unnamed, and its contents reside in the computer's RAM. The clipboard provides an application programming interface by which programs can specify cut, copy and paste operations. It is left to the program to define methods for the user to command these operations, which may include keybindings and menu selections. When an element is copied or cut, the clipboard must store enough information to enable a sensible result no matter where the element is pasted. Application programs may extend the clipboard functions that the operating system provides. A clipboard manager may give the user additional control over the clipboard. Specific clipboard semantics vary among operating systems, can also vary between versions of the same system, and can sometimes be changed by programs and by user preferences. Windows, Linux and macOS support a single clipboard transaction.
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  • 01 Nov 2022
Topic Review
Nitroglycerin (Medication)
Nitroglycerin, also known as glyceryl trinitrate (GTN), is a medication used for heart failure, high blood pressure, anal fissures, painful periods, and to treat and prevent chest pain caused by decreased blood flow to the heart (angina) or due to the recreational use of cocaine. This includes chest pain from a heart attack. It is taken by mouth, under the tongue, applied to the skin, or by injection into a vein. Common side effects include headache and low blood pressure. The low blood pressure can be severe. It is unclear if use in pregnancy is safe for the baby. It should not be used together with medications within the sildenafil (PDE5 inhibitor) family due to the risk of low blood pressure. Nitroglycerin is in the nitrate family of medications. While it is not entirely clear how it works, it is believed to function by dilating blood vessels. Nitroglycerin was written about as early as 1846 and came into medical use in 1878. It is on the World Health Organization's List of Essential Medicines. The drug nitroglycerin (GTN) is a dilute form of the same chemical used as the explosive, nitroglycerin. Dilution makes it non-explosive. In 2019, it was the 184th most commonly prescribed medication in the United States, with more than 3 million prescriptions.
  • 2.5K
  • 01 Nov 2022
Topic Review
Time-resolved Spectroscopy
In physics and physical chemistry, time-resolved spectroscopy is the study of dynamic processes in materials or chemical compounds by means of spectroscopic techniques. Most often, processes are studied after the illumination of a material occurs, but in principle, the technique can be applied to any process that leads to a change in properties of a material. With the help of pulsed lasers, it is possible to study processes that occur on time scales as short as 10−16 seconds.
  • 1.3K
  • 01 Nov 2022
Topic Review
1888 Ritter Island Tsunami
On the morning of March 13, 1888, an explosion took place on Ritter Island, a small volcanic island in the Bismarck and Solomon Seas, between New Britain and Umboi Island. This event is the largest volcanic island sector collapse in recent history. The explosion resulted in the almost complete loss of the island and generated a tsunami with runups of up to 20 meters (66 ft) that caused damage more than 600 kilometers (370 mi) away and killed anywhere between 500 and 3,000 on neighbouring islands, including scientists and explorers.
  • 1.3K
  • 01 Nov 2022
Topic Review
Chapter and Conventual Mass
As currently used, the terms Chapter Mass (for chapters of canons) and Conventual Mass (for most other houses of religious) refer to the Mass celebrated by and for a community of priests or for a community of priests and brothers or sisters. Such Masses are normally concelebrated by most or all of the priests in a house in the case of a house of an order or other religious community that includes priests. The conventual Mass is therefore the daily "community Mass" for a local religious family – whether a convent, monastery or other house. It is normally linked with the Liturgy of the Hours, at which the community gathers to worship as a body: there are special norms in the rubrics for combining any one of the hours of the Divine Office with the celebration of Mass. The Mass and Office celebrated are those of the day, according to the rubrics and ordo of the order or house. The modern concept of the conventual Mass is laid out in the General Instruction of the Roman Missal.
  • 545
  • 01 Nov 2022
Topic Review
Institute for Medieval Studies, Leeds
The Institute for Medieval Studies (IMS) at the University of Leeds, founded in 1967, is a leading research and teaching institute in the field of medieval studies. It is home to the International Medieval Bibliography and the International Medieval Congress.
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  • 01 Nov 2022
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