John Ray

John Ray FRS was an English naturalist regarded as one of the earliest of the English parson-naturalists. Until 1670, he wrote his name as John Wray. From on, he used'Ray', after "having ascertained that such had been the practice of his family before him", he published important works on botany and natural theology. His classification of plants in his Historia Plantarum, was an important step towards modern taxonomy. Ray rejected the system of dichotomous division by which species were classified according to a pre-conceived, either/or type system, instead classified plants according to similarities and differences that emerged from observation, he was among the first to attempt a biological definition for the concept of species. John Ray was born in the village of Black Notley in Essex, he is said to have been born in his father having been the village blacksmith. After studying at Braintree school, he was sent at the age of sixteen to Cambridge University: studying at Trinity College. At Catharine Hall, his tutor was Daniel Duckfield, transferred to Trinity where his tutor was James Duport, his intimate friend and fellow-pupil the celebrated Isaac Barrow.

Ray was chosen minor fellow of Trinity in 1649, major fellow. He held many college offices, becoming successively lecturer in Greek and humanity, praelector and college steward. Among these sermons were his discourses on The wisdom of God manifested in the works of the creation, Deluge and Dissolution of the World. Ray was highly regarded as a tutor and he communicated his own passion for natural history to several pupils. Ray's student, Isaac Barrow, helped Francis Willughby learn mathematics and the Ray collaborated with Willughby later, it was at Trinity that he came under the influence of John Wilkins, when the latter was appointed master of the college in 1659. After leaving Cambridge in 1663 he spent some time travelling both in the continent. In 1673, Ray married Margaret Oakley of Launton in Oxfordshire. In 1679, he removed to his birthplace at Black Notley, where he afterwards remained, his life there was uneventful, although he had poor health, including chronic sores. Ray kept writing books and corresponded on scientific matters, collaborating with his doctor and contemporary Samuel Dale.

He lived, to the age of seventy-seven, dying at Black Notley. He is buried in the churchyard of St Paul where there is a memorial to him, he is regarded as one of the earliest of the English parson-naturalists. At Cambridge, Ray spent much of his time in the study of natural history, a subject which would occupy him for most of his life, from 1660 to the beginning of the eighteenth century; when Ray found himself unable to subscribe as required by the ‘Bartholomew Act’ of 1662 he, along with 13 other college fellows, resigned his fellowship on 24 August 1662 rather than swear to the declaration that the Solemn League and Covenant was not binding on those who had taken it. Tobias Smollett quoted the reasoning given in the biography of Ray by William Derham: "The reason of his refusal was not as some have imagined, his having taken the solemn league and covenant, his religious views were in accord with those imposed under the restoration of Charles II of England, he continued as a layman in the Established Church of England.

From this time onwards he seems to have depended chiefly on the bounty of his pupil Francis Willughby, who made Ray his constant companion while he lived. Willughby arranged that after his death, Ray would have 6 shillings a year for educating Willughby's two sons. In the spring of 1663 Ray started together with Willughby and two other pupils on a tour through Europe, from which he returned in March 1666, parting from Willughby at Montpellier, whence the latter continued his journey into Spain, he had in three different journeys travelled through the greater part of Great Britain, selections from his private notes of these journeys were edited by George Scott in 1760, under the title of Mr Ray's Itineraries. Ray himself published an account of his foreign travel in 1673, entitled Observations topographical and physiological, made on a Journey through part of the Low Countries, Germany and France. From this tour Ray and Willughby returned laden with collections, on which they meant to base complete systematic descriptions of the animal and vegetable kingdoms.

Willughby undertook the former part, dying in 1672, left only an ornithology and ichthyology for Ray to edit. The plants gathered on his British tours had been described in his Catalogus plantarum Angliae, which formed the basis for English floras. In 1667 Ray was elected Fellow of the Royal Society, in 1669 he and Willughby published a paper on Experiments concerning the Motion of Sap in Trees. In 1671, he presented the research of Francis Jessop on formic acid t

Shared memory

In computer science, shared memory is memory that may be accessed by multiple programs with an intent to provide communication among them or avoid redundant copies. Shared memory is an efficient means of passing data between programs. Depending on context, programs may run on multiple separate processors. Using memory for communication inside a single program, e.g. among its multiple threads, is referred to as shared memory. In computer hardware, shared memory refers to a block of random access memory that can be accessed by several different central processing units in a multiprocessor computer system. Shared memory systems may use: uniform memory access: all the processors share the physical memory uniformly. A shared memory system is easy to program since all processors share a single view of data and the communication between processors can be as fast as memory accesses to a same location; the issue with shared memory systems is that many CPUs need fast access to memory and will cache memory, which has two complications: access time degradation: when several processors try to access the same memory location it causes contention.

Trying to access nearby memory locations may cause false sharing. Shared memory computers cannot scale well. Most of them have ten or fewer processors; such cache coherence protocols can, when they work well, provide high-performance access to shared information between multiple processors. On the other hand, they can sometimes become a bottleneck to performance. Technologies like crossbar switches, Omega networks, HyperTransport or front-side bus can be used to dampen the bottleneck-effects. In case of a Heterogeneous System Architecture, the memory management unit of the CPU and the input–output memory management unit of the GPU have to share certain characteristics, like a common address space; the alternatives to shared memory are distributed memory and distributed shared memory, each having a similar set of issues. In computer software, shared memory is either a method of inter-process communication, i.e. a way of exchanging data between programs running at the same time. One process will create an area in RAM.

This is most used for shared libraries and for Execute in place. Since both processes can access the shared memory area like regular working memory, this is a fast way of communication. On the other hand, it is less scalable, as for example the communicating processes must be running on the same machine, care must be taken to avoid issues if processes sharing memory are running on separate CPUs and the underlying architecture is not cache coherent. IPC by shared memory is used for example to transfer images between the application and the X server on Unix systems, or inside the IStream object returned by CoMarshalInterThreadInterfaceInStream in the COM libraries under Windows. Dynamic libraries are held in memory once and mapped to multiple processes, only pages that had to be customized for the individual process are duplicated with a mechanism known as copy-on-write that transparently copies the page when a write is attempted, lets the write succeed on the private copy. POSIX provides a standardized API for using POSIX Shared Memory.

This uses the function shm_open from sys/mman.h. POSIX interprocess communication includes the shared-memory functions shmat, shmctl and shmget. Unix System V provides an API for shared memory as well; this uses shmget from sys/shm.h. BSD systems provide "anonymous mapped memory"; the shared memory created by shm_open is persistent. It stays in the system; this has a drawback that if the process crashes and fails to clean up shared memory it will stay until system shutdown. POSIX provides the mmap API for mapping files into memory. Linux distributions based on the 2.6 kernel and offer /dev/shm as shared memory in the form of a RAM disk, more as a world-writable directory, stored in memory. Both the RedHat and Debian based. Support for this type of RAM disk is optional within the kernel configuration file. On Windows, one can use CreateFileMapping and MapViewOfFile functions to map a region of a file into memory in multiple processes; some C++ libraries provide a object-oriented access to shared memory functionality.

For example, Boost contains the Boost. Interproces

Museum of the Armed Forces (Angola)

The Museum of the Armed Forces is located in Fortaleza de São Miguel de Luanda, in Luanda, Angola. Founded in 1975, following the independence of Angola, the museum includes bi-motor airplanes, combat vehicles, diverse arms and artifacts used during the Angolan War of Independence, the South African Border War, the Angolan Civil War; the museum contains statuary which ornamented the avenues and plazas of colonial Luanda, which were removed after independence. These include the statue of Diogo Cão, the first European to set foot in Angola, of Paulo Dias de Novais, founder of the city of São Paulo da Assunção de Luanda, of Vasco da Gama, of famous Portuguese poet Luís de Camões, among others; the museum grounds and outdoor exhibits, long in a delipidated state, underwent an extensive restoration project at some point between 1997 and 2013. BRDM-2 BTR-152 Buffel Eland-90 GAZ-66 Panhard AML-90 Renault 6 UAZ-469 Withings Recovery Vehicle 15 cm sFH 18 9K38 Igla Ox-wagon T-6 Texan Wreckage of downed South African Air Force Puma and Mirage IIIRZ Museum of the Armed Forces, short English description Roteiros Turísticos Museu das Forças Armadas