In optics, the numerical aperture of an optical system is a dimensionless number that characterizes the range of angles over which the system can accept or emit light. By incorporating index of refraction in its definition, NA has the property that it is constant for a beam as it goes from one material to another, provided there is no refractive power at the interface; the exact definition of the term varies between different areas of optics. Numerical aperture is used in microscopy to describe the acceptance cone of an objective, in fiber optics, in which it describes the range of angles within which light, incident on the fiber will be transmitted along it. In most areas of optics, in microscopy, the numerical aperture of an optical system such as an objective lens is defined by N A = n sin ⁡ θ, where n is the index of refraction of the medium in which the lens is working, θ is the maximal half-angle of the cone of light that can enter or exit the lens. In general, this is the angle of the real marginal ray in the system.

Because the index of refraction is included, the NA of a pencil of rays is an invariant as a pencil of rays passes from one material to another through a flat surface. This is shown by rearranging Snell's law to find that n sin θ is constant across an interface. In air, the angular aperture of the lens is twice this value; the NA is measured with respect to a particular object or image point and will vary as that point is moved. In microscopy, NA refers to object-space NA unless otherwise noted. In microscopy, NA is important; the size of the finest detail that can be resolved is proportional to λ/2NA, where λ is the wavelength of the light. A lens with a larger numerical aperture will be able to visualize finer details than a lens with a smaller numerical aperture. Assuming quality optics, lenses with larger numerical apertures collect more light and will provide a brighter image, but will provide shallower depth of field. Numerical aperture is used to define the "pit size" in optical disc formats.

Increasing the magnification and the numerical aperture of the objective reduces the working distance, i.e. the distance between front lens and specimen. Numerical aperture is not used in photography. Instead, the angular aperture of a lens is expressed by the f-number, written f/ or N, defined as the ratio of the focal length f to the diameter of the entrance pupil D: N = f D; this ratio is related to the image-space numerical aperture. Based on the diagram at the right, the image-space numerical aperture of the lens is: NA i = n sin ⁡ θ = n sin ⁡ ≈ n D 2 f, thus N ≈ 1/2NAi, assuming normal use in air; the approximation holds when the numerical aperture is small, but it turns out that for well-corrected optical systems such as camera lenses, a more detailed analysis shows that N is exactly equal to 1/2NAi at large numerical apertures. As Rudolf Kingslake explains, "It is a common error to suppose that the ratio is equal to tan θ, not sin θ... The tangent would, of course, be correct if the principal planes were plane.

However, the complete theory of the Abbe sine condition shows that if a lens is corrected for coma and spherical aberration, as all good photographic objectives must be, the second principal plane becomes a portion of a sphere of radius f centered about the focal point". In this sense, the traditional thin-lens definition and illustration of f-number is misleading, defining it in terms of numerical aperture may be more meaningful; the f-number describes the light-gathering ability of the lens in the case where the marginal rays on the object side are parallel to the axis of the lens. This case is encountered in photography, where objects being photographed are far from the camera; when the object is not distant from the lens, the image is no longer formed in the lens's focal plane, the f-number no longer describes the light-gathering ability of the lens or the image-side numerical aperture. In this case, the numerical aperture is related to what is sometimes called the "working f-number" or "effective f-number".

The working f-number is defined by modifying the relation above, taking into account the magnification from object to image: 1 2 NA i = N w = N, where Nw is the working f-number, m is the lens's magnification for an object a particular distance away, P is the pupil magnification, the NA is defined in terms of the angle of the marginal ray as before

Siddha Baba Temple is a Hindu temple of Lord Shiva located near the city of Butwal, Dobhan-5, Palpa district of Nepal. The temple is visited by the people all over Nepal and by the Hindus of Palpa and Rupandehi and neighboring districts, it is believed. There is a tradition to release a pigeon; this tradition has contributed to large number of pigeon population around the temple. Hindu people worship at the temple of Siddha Baba during the days of Saturday and various religious festivals directly and indirectly connected to god Shiva. During the festivals of Shivaratri, a large numbers of Hindus go to the temple for worship; the temple of Siddha Baba lies in Dobhan-5, Palpa district, Nepal at a distance of about 2 km from Butwal Sub-metro city. The temple is located at left bank of Tinau Riveron the way to Pokhara via Siddhartha Highway. A small river named Chidiya Khola flows near the temple

Samuel Fiddian M. A. was a schoolteacher, remembered as the first principal of Prince Alfred College in Adelaide, South Australia. He founded a Grammar School in Creswick, Victoria, of which he was principal and proprietor from 1872 to 1903. Fiddian was born in Castle Donington, a son of English Wesleyan Methodist Rev. Samuel Fiddian and his wife Grace Burall Fiddian née Paull and was educated at Woodhouse Grove, the school for sons of the Methodist clergy at Huddersfield, he spent 1859–1862 in Tasmania, where he taught at Horton College, before acquiring his MA at Cambridge University, where he was wrangler of St. John's College, he was for a short time mathematics master at Wesley College, Sheffield was brought out to South Australia in 1869 to take up an appointment as foundation headmaster of Prince Alfred College, which operated from a schoolroom behind the Pirie Street Methodist Church, the Kent Town campus not yet ready for occupation. He arrived in Melbourne aboard Essex early in January 1869.

The Aldinga, taking Fiddian to Adelaide, had not yet arrived when classes started but he was able to take up his duties shortly after he landed. While in Adelaide he was appointed to the board of governors of the South Australian Institute, he resigned in December 1870 and left Adelaide early in January 1871. For a year he taught mathematics at Geelong College before founding Creswick Grammar School, of which he was proprietor and headmaster from 1872 to 1903, he may have been assisted by his sister Mary Paull Fiddian. His service to the community is recognised by an obelisk in Cambridge Street, Victoria. Fiddian Range in the Northern Territory may have been named for him. Samuel Fiddian married Sophia Robin, eldest daughter of James Robin on 9 January 1872, they lived in Victoria. Their children included: Rev. James Rowland Fiddian MSc was minister of St. Andrews Presbyterian Church, South Australia 1909–1917 before returning to Victoria, was Moderator of the Presbyterian Church of Victoria from 1938 to 1940.

Samuel Fiddian, jr. married his cousin, Margaret N. Robin, eldest daughter of Henry Nicholas Robin, on 21 March 1906, he was a teacher in Geelong, became part-owner of James Robin & Co. in 1909 William de Jersey Fiddian with the Bank of New South Wales at Sydney Charlotte Marguerite'Rita' Fiddian drowned with her cousin Maurice Robin at Ocean Grove, Victoria on 28 December 1896. Samuel Fiddian died in Liverpool, England, as he was about to return to Australia

Koilkonda is a Mandal in Mahbubnagar district, Telangana. Koilkonda is located at 16.7500°N 77.7833°E / 16.7500. It has an average elevation of 464 metres. Situated nearby perched on a hilltop is the Koilkonda Fort, the erstwhile outpost of the Qutb Shahi dynasty, it is on the NH 125 km from Hyderabad. To reach the top, one needs to trudge across a deep canyon on the west or a series of streams if coming through east before reaching a plight of steps that leads to the fort. There are seven gates leading to the fort; the first one has an inscription of Ibrahim Qutb Shah that dates back to 1550. The fourth gate leads to a dilapidated palace. Along with the fort, which itself is a magnificent structure, there is a mosque and an eidgah. There is a Fort in Koilkonda built by one of the Golkonda kings. Zilla Parishad High School. Guru Raghavendra Vidyalaya State Bank of Hyderabad; the villages in Koilkonda mandal include: Abhangapatnam Acharyapur Ankilla Burugupally Chandapur Chandraspalle Dammaipally Garlapad Ibrahimnagar Jamalpur Keshavapoor Khazipur Koilkonda Kothlabad Malkapur Manikonda Modipur Parpalle Perikiveedu Rampur Sanganonipally Serivenkatapur Suraram Thirumulampalle Veerampally Vinjamur Yellareddi Pally Lingupally

"Jeans On" is a song by British musician David Dundas from his 1977 self-titled debut album. Released as a single the previous year, it was first featured as a television advertising jingle for Brutus Jeans; the popularity of the commercial led to the recording of "Jeans On" as a full-length song, with some lyrical changes. The single became Dundas's biggest hit, peaking at number 3 on the UK Singles Chart and number 17 on the U. S. Billboard Hot 100. Dundas recorded a French language version of the song, titled "Blue Jeans"; the opening piano riff of the song was looped and sampled for British electronic musician Fatboy Slim's 1998 track "Sho Nuff". The song is covered by Keith Urban in the 2002 album Golden Road

Glan Llyn is the name of a mixed-use community development, in the east of Newport, south Wales on the heavy end of the former Llanwern steelworks, at the edge of the Caldicot Moors. The moors have a wealth of buried archaeology of international importance, including prehistoric and Roman landscapes which have been protected and preserved over the years by alluvial deposits; the steel production section of Llanwern steel works closed in 2001, leading to the loss of 1,300 jobs. A finishing plant still remains in operation today. After the closure of steel production, Corus Group started the process of finding a redevelopment partner, choosing St. Modwen Properties, who in 2004 bought a 600-acre package of land; the redevelopment process started with the clearing of the former steel works buildings, making the site environmentally safe. This allowed the site to act as a Park & Ride facility for the 2010 Ryder Cup event at the Celtic Manor Resort. Up to 400,000 tonnes of concrete from the former steel works will be used in the redevelopment of the site.

St Modwen have set out a £1Bn mixed-use redevelopment plan for the site, which it is envisaged will take 20 years to complete, in circa 2026–28. The new community plan includes the construction of 4,000 homes, with a supporting infrastructure that includes schools, a police station, pub/restaurant, community centre as well as a number of open spaces that will include two new lakes and a water theme park, new access roads, a GPs' surgery plus health and leisure facilities; the first phase was approved in April 2010 by Newport City Council, which will create 1,330 homes, the district centre, a primary school and the west lake. After gaining specific planning permission in April 2011, Persimmon plc started work on the construction of the first 307 homes in September 2011; the Persimmon/Charles Church developments were completed in 2016. St Modwen is building houses around the Pools and Lakeside Parks areas of the development, Bellway Homes commenced work on building further houses adjacent to the St Modwen site at Monk's Meadow in autumn 2016.

There are plans for a small railway halt at the far end of the development. Due to its proximity to the M4 and the Second Severn Crossing, low property prices it has proved to be popular with commuters working in Bristol, its popularity has risen in recent years following the abolition of the tolls on both motorway bridges at the end of 2018. Glan Llyn is home to the mechanical clock known as "In the Nick of Time" created by sculptor Andy Plant; the clock was commissioned and paid for by Newport Council at a cost of £100,000, as part of Ebbw Vale Garden Festival. On the hour, the structure would open to reveal the hidden characters inside. After the festival event the clock was relocated to John Frost Square, where it remained until the redevelopment of the area into Friars Walk. After seven years in storage it was relocated to the "Mynedfa" roundabout at Glan Llyn; the clock is a popular landmark in the area. The development has two main parks - Pools Park and Lakeside Park, both of which include man made lakes, are home to an extensive range of wildfowl.

Pools Park was original home to the Spencer Steel Works Angling Club, was located just inside the main entrance to the steel works. The parks are popular with local residents, as well as visitors to the nearby Newport Retail Park. Central Park, a smaller park for younger children, is located in the centre of the development at Sgwâr Brinell; the development is close to a number of popular tourist attractions, including the RSPB reserve at the Newport Wetlands and the world-famous Newport Transporter Bridge. Glan Llyn is part of the Llanwern electoral ward, which itself is part of the Newport East UK parliamentary constituency. Glan Llyn is situated within the catchment area for Lliswerry High School. A new English medium primary school is under development at the western end of the site, it is anticipated that this will be opened and established by the mid 2020s. Llanwern Llanwern A. F. C. Glan Llyn development website Celtic Business Park www.geograph.co.uk: photos of Llanwern and surrounding area BBC Wales video report on master plan approval, April 2010