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Side Lobe
In antenna engineering, side lobes or sidelobes are the lobes (local maxima) of the far field radiation pattern of an antenna or other radiation source, that are not the main lobe. The radiation pattern of most antennas shows a pattern of "lobes" at various angles, directions where the radiated signal strength reaches a maximum, separated by "nulls", angles at which the radiated signal strength falls to zero. This can be viewed as the diffraction pattern of the antenna. In a directional antenna in which the objective is to emit the radio waves in one direction, the lobe in that direction is designed to have a larger field strength than the others; this is the "main lobe". The other lobes are called "side lobes", and usually represent unwanted radiation in undesired directions. The side lobe directly behind the main lobe is called the back lobe. The longer the antenna relative to the radio wavelength, the more lobes its radiation pattern has. In transmitting antennas, excessive side lobe radiation wastes energy and may cause interference to other equipment. Another disadvantage is that confidential information may be picked up by unintended receivers. In receiving antennas, side lobes may pick up interfering signals, and increase the noise level in the receiver. The power density in the side lobes is generally much less than that in the main beam. It is generally desirable to minimize the sidelobe level (SLL), which is measured in decibels relative to the peak of the main beam. The main lobe and side lobes occur for both transmitting and receiving. The concepts of main and side lobes, radiation pattern, aperture shapes, and aperture weighting, apply to optics (another branch of electromagnetics) and in acoustics fields such as loudspeaker and sonar design, as well as antenna design. Because an antenna's far field radiation pattern is a Fourier Transform of its aperture distribution, most antennas will generally have sidelobes, unless the aperture distribution is a Gaussian, or if the antenna is so small as to have no sidelobes in the visible space. Larger antennas have narrower main beams, as well as narrower sidelobes. Hence, larger antennas have more sidelobes in the visible space (as the antenna size is increased, sidelobes move from the evanescent space to the visible space).
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  • 28 Nov 2022
Topic Review
GuideStar
GuideStar USA, Inc. is an information service specializing in reporting on U.S. nonprofit companies. In 2016, its database provided information on 2.5 million organizations. GuideStar was one of the first central sources of information on U.S. nonprofits and is the world's largest source of information about nonprofit organizations. GuideStar was founded in Williamsburg, Virginia in September 1994 and received tax-exempt status in 1996, the same year the company began posting nonprofit organizations' financial reports to the World Wide Web. GuideStar also serves to verify that a recipient organization is established and that donated funds go where the donor intended for individuals looking to give in the wake of disasters. In 2013, GuideStar announced major changes to its GuideStar Exchange program, which allows nonprofits to supplement the public information that is available from the IRS. GuideStar Nonprofit Profiles implemented three seals based on the information a nonprofit provides in its profile: Bronze, Silver, and Gold. In 2016, a new seal that allowed nonprofits to share progress and results for their mission, GuideStar Platinum, was introduced.
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  • 28 Nov 2022
Topic Review
Chrysler Minivan (AS)
The second-generation Chrysler minivans are a series of minivans that were manufactured and marketed by Chrysler Corporation in North America and Europe from 1991 to 1995. Officially designated the AS platform by Chrysler, the second-generation minivans were again sold in passenger and cargo configurations by the Chrysler, Plymouth, and Dodge divisions. Launched in late 1990 for the 1991 model year, the second-generation minivans were an extensive revision of the first-generation chassis and body. The model range became the first minivans offered with driver-side airbags (1991) and with optional integrated child safety seats (1992). While adding all-wheel drive as an option for the first time, the AS platform would also mark the last offering of a manual transmission. As with its predecessor, Chrysler assembled second-generation minivans at Windsor Assembly in Windsor, Ontario, Canada, with additional production at Saint Louis (North) Assembly in Fenton, Missouri from 1990 to 1994. In 1992, to supplement exports from the United States, the Chrysler Voyager began production in Graz, Austria (in the Eurostar joint venture factory between Chrysler and Steyr-Daimler-Puch). For the 1996 model year, the AS-generation minivans were replaced by the NS platform, marking the first complete redesign of the Chrysler minivans since their introduction.
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Topic Review
Catholic Theology of Scripture
The theology of Scripture in the Roman Catholic church has evolved much since the Second Vatican Council of Catholic Bishops ("Vatican II", 1962-1965). This article explains the theology (or understanding) of Scripture that has come to dominate in the Catholic Church today. It focuses on the Church’s response to various areas of study into the original meaning of texts.
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Topic Review
List of Unnumbered Minor Planets: 2003 A–R
This is a partial list of unnumbered minor planets for principal designations assigned between 1 January 2003 and 15 September 2003 (A–R).
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  • 28 Nov 2022
Topic Review
Bt Brinjal
The Bt brinjal is a suite of transgenic brinjals (also known as an eggplant or aubergine) created by inserting a crystal protein gene (Cry1Ac) from the soil bacterium Bacillus thuringiensis into the genome of various brinjal cultivars. The insertion of the gene, along with other genetic elements such as promoters, terminators and an antibiotic resistance marker gene into the brinjal plant is accomplished using Agrobacterium-mediated genetic transformation. The Bt brinjal has been developed to give resistance against lepidopteron insects, in particular the Brinjal Fruit and Shoot Borer (Leucinodes orbonalis)(FSB). Mahyco, an Indian seed company based in Jalna, Maharashtra, has developed the Bt brinjal. The genetically modified brinjal event is termed Event EE 1, and Mahyco have also applied for approval of two brinjal hybrids. The Event EE 1 was introgressed by plant breeding into various local varieties by University of Agricultural Sciences, Dharwad and Tamil Nadu Agricultural University, Coimbatore. Some of the cultivars of brinjal include: Malpur local, Manjari gota, Kudachi local, Udupi local, 112 GO, and Pabkavi local. It was approved for commercialization in India in 2009, but - after an apparent public outcry and rounds of debates in which representatives from Mahyco, the scientific community, and NGO's spoke on the topic - the then Indian Environment Minister, Jairam Ramesh, facilitated a moratorium on its release until further, unspecified, tests were conducted. Bt brinjal was approved for commercial release in Bangladesh in 2013.
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  • 28 Nov 2022
Topic Review
Wireless Electronic Devices and Health
The World Health Organization (WHO) has researched electromagnetic fields (EMFs) and their alleged effects on public health, concluding that such exposures within recommended limits do not produce any known adverse health effect. In response to public concern, the WHO established the International EMF Project in 1996 to assess the scientific evidence of possible health effects of EMF in the frequency range from 0 to 300 GHz. They have stated that although extensive research has been conducted into possible health effects of exposure to many parts of the frequency spectrum, all reviews conducted so far have indicated that, as long as exposures are below the limits recommended in the ICNIRP (1998) EMF guidelines, which cover the full frequency range from 0–300 GHz, such exposures do not produce any known adverse health effect. Stronger or more frequent exposures to EMF can be unhealthy, and in fact serve as the basis for electromagnetic weaponry. International guidelines on exposure levels to microwave frequency EMFs such as ICNIRP limit the power levels of wireless devices and it is uncommon for wireless devices to exceed the guidelines. These guidelines only take into account thermal effects, as nonthermal effects have not been conclusively demonstrated. The official stance of the British Health Protection Agency is that “[T]here is no consistent evidence to date that WiFi and WLANs adversely affect the health of the general population”, but also that “...it is a sensible precautionary approach...to keep the situation under ongoing review...”. In 2011, International Agency for Research on Cancer (IARC), an agency of the World Health Organization, classified wireless radiation as Group 2B – possibly carcinogenic. That means that there "could be some risk" of carcinogenicity, so additional research into the long-term, heavy use of wireless devices needs to be conducted.
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Topic Review
Hepacivirus C
Hepacivirus C (HCV) is a small (55–65 nm in size), enveloped, positive-sense single-stranded RNA virus of the family Flaviviridae. The Hepacivirus C is the cause of hepatitis C and some cancers such as liver cancer (hepatocellular carcinoma, abbreviated HCC) and lymphomas in humans.
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  • 15 Dec 2022
Topic Review
Kouvola
Kouvola (Finnish pronunciation: [ˈkou̯ʋolɑ]) is a city and municipality in southeastern Finland. It is located along the Kymijoki River in the region of Kymenlaakso, 62 kilometres (39 mi) kilometers east of Lahti, 87 kilometres (54 mi) west of Lappeenranta and 134 kilometres (83 mi) northeast of the capital, Helsinki. With Kotka, Kouvola is one of the capital centers and is the largest city in the Kymenlaakso region. Kouvola is bordered by the municipalities of Hamina, Heinola, Iitti, Kotka, Lapinjärvi, Loviisa, Luumäki, Miehikkälä, Mäntyharju, Pyhtää and Savitaipale. Kouvola, which had population growth as late as the 1980s, has suffered a loss of migration since the 1990s. Over time, the loss has only deepened, so that at the end of the 2010s Kouvola was Finland's worst migration loss area. Natural demographics have also trended downward; in 2017, more than 450 more people died in the city than new ones were born. The reasons for the emigration are thought to be largely due to job losses in the region.
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Topic Review
Climate of the Alps
The climate of the Alps is the climate, or average weather conditions over a long period of time, of the exact middle Alpine region of Europe. As air rises from sea level to the upper regions of the atmosphere the temperature decreases. The effect of mountain topography on prevailing winds is to force warm air from the lower region into an upper zone where it expands in volume at the cost of a proportionate loss of heat, often accompanied by the precipitation of moisture in the form of snow, rain or hail. The position of the Alps in the central European continent profoundly affects the climate of all the surrounding regions. The accumulation of vast masses of snow, which have gradually been converted into permanent glaciers, maintains a gradation of very different climates within the narrow space that intervenes between the foot of the mountains and their upper ridges; it cools breezes that waft to the plains on either side, but its most important function is to regulate the water supply of the large region which is traversed by the streams of the Alps. Nearly all the moisture that is precipitated during fall, winter, and spring is stored in the form of snow and gradually diffused in the course of the succeeding summer; even in the hottest and driest seasons the reserves accumulated during a long preceding period of years in the form of glaciers are available to maintain the regular flow of the greater streams. Nor is this all; the lakes that fill several of the main valleys on the southern side of the Alps are somewhat above the level of the plains of Lombardy and Venetia, and afford an inexhaustible supply of water, which, from a remote period, has been used for that system of irrigation to which they owe their proverbial fertility. Six regions or zones, which are best distinguished by their characteristic vegetation, are found in the Alps. It is an error to suppose that these are indicated by absolute height above sea level. Local conditions of exposure to the Sun, protection from cold winds, or the reverse, are of primary importance in determining the climate and the corresponding vegetation.
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