Observation info for years before 1492 is completely unavailable because record keeping was non-existent in the pre-Columbian era, and any records that may have once existed have long since been lost. Even info from the early years of the Columbian era is suspect and incomplete because the difference between a hurricane and an extratropical system was not drawn by Renaissance scientists and sailors and because European exploration and colonization of the regions affected by hurricanes did not begin in earnest until the mid-16th century.
However, paleotempestological research allows reconstruction of pre-historic hurricane activity trends on timescales of centuries to millennia. A theory has been postulated that an anti-phase pattern exists between the Gulf of Mexico coast and the Atlantic coast. During the quiescent periods, a more northeasterly position of the Azores High would result in more hurricanes being steered towards the Atlantic coast. During the hyperactive period, more hurricanes were steered towards the Gulf coast as the Azores High—controlled by the North Atlantic Oscillation—was shifted to a more southwesterly position near the Caribbean. In fact, few major hurricanes struck the Gulf coast during 3000–1400 BC and again during the most recent millennium; these quiescent intervals were separated by a hyperactive period during 1400 BC and 1000 AD, when the Gulf coast was struck frequently by catastrophic hurricanes and their landfall probabilities increased by 3–5 times. On the Atlantic coast, chance of landfalling hurricanes has doubled in the recent millennium compared to the one and a half millennia before.
Valley Parade
Valley Parade, also known by its sponsored name of the Coral Windows Stadium is a football stadium in Bradford in England. It is home to the club Bradford City A.F.C. It was built in 1886. In 1985, a fire in one of the stands killed 56 people.
Levi Lincoln Sr.
Levi Lincoln, Sr. (May 15, 1749–April 14, 1820) was an American revolutionary. He was a Minuteman at the beginning of the American Revolutionary War, a state legislator in Massachusetts, Governor of Massachusetts, Lieutenant Governor of Massachusetts, a U.S. Representative, Attorney General for President Thomas Jefferson and Acting Secretary of State.
James R. Schlesinger
James Rodney Schlesinger (February 15, 1929 - March 27, 2014) was United States Secretary of Defense from 1973 to 1975 under presidents Richard Nixon and Gerald Ford. He became America's first Secretary of Energy under Jimmy Carter.
On March 27, 2014, Schlesinger died from complications of pneumonia at a Baltimore hospital. He was 85.
Simultaneous multithreading
Simultaneous multithreading, acronym SMT, is a technique for improving the overall efficiency of superscalar CPUs with Hardware multithreading. SMT permits multiple independent threads of execution to better utilize the resources provided by modern computer architectures.
Multithreading is similar in concept to multitasking but is implemented at the thread level of execution in modern superscalar processors.
In processor design, there are two ways to increase on-chip parallelism with less resource requirements:
There are many ways to support more than one thread inside a chip, namely:
The key factor to distinguish them is to look at how many instructions the processor can issue in one cycle and how many threads from which the instructions come.
Out-of-order execution
In computer engineering, out-of-order execution, OoOE, is a technique used in most high-performance microprocessors to make use of cycles that would otherwise be wasted by a certain type of costly delay. Most modern CPU designs include support for out of order execution.
The key concept of OoO processing is to allow the processor to avoid a class of delays (termed: ""stalls "") that occur when the data needed to perform an operation are unavailable.
OoO processors fill these "slots" in time with other instructions that are ready, then re-order the results at the end to make it appear that the instructions were processed as normal. The way the instructions are ordered in the original computer code is known as program order, in the processor they are handled in data order (the order in which the data, operands, become available in the processor's registers). Fairly complex circuitry is needed to convert from one ordering to the other and maintain a logical ordering of the output; the processor itself appears to be running the instructions in random order.
The benefit of OoO processing grows as the instruction pipeline expands and the speed difference between main memory (or cache memory) and the processor increases. On modern machines, the processor runs many times faster than the memory, so during the time an in-order processor spends waiting for data to arrive, it could have processed a large number of instructions.
In earlier In-order processors, the processing of instructions is normally done in these steps:
Out-of-order processors breaks up the processing of instructions into these steps:
In the examples outlined above, the OoO processor avoids the stall that occurs in step (2) of the in-order processor when the instruction is not completely ready to be processed due to missing data.
Speculative execution
In computer science, speculative execution is the execution of code, before being sure if the result will be needed.
The technique is used in most high-performance microprocessors to execute a complete instructions or parts of instructions before being sure whether this execution is required
In the context of functional programming, the term "speculative evaluation" is used instead.
Branch prediction
In computer architecture, a branch predictor is the part of a processor that determines whether a conditional branch (jump) in the instruction flow of a program is likely to be taken or not. This is called branch prediction.
Branch predictors are important in today's modern, superscalar processors for achieving high performance. They allow processors to fetch and execute instructions without waiting for a branch to be resolved.
Almost all pipelined processors do branch prediction of some form, because they must guess the address of the next instruction to fetch before the current instruction has been executed.
Many earlier microprogrammed CPUs did not do branch prediction because there was little or no performance requirements; for this reason there is no need for altering the flow of the instruction stream.
Aka
A.K.A, AKA, Aka or aka may refer to:
Key exchange
Key exchange is any method in cryptography by which cryptographic keys are exchanged between users, allowing use of a cryptographic system.
If two parties wish to exchange encrypted messages, each needs to know how to decrypt received messages and to encrypt sent messages. The information they require to do so depends on the encryption technique they might use. If they use a code, both will require a copy of the same codebook. If they use a cipher, they will need appropriate keys. If the cipher is a symmetric key cipher, both will need a copy of the same key. If an asymmetric key cipher with the public/private key property, both will need the other's public key.
The key exchange problem is how to exchange whatever keys or other information needed so, in such a way, that no one else can obtain a copy. Usually, this required trusted secure channel. With the arrival of (public key / private key) cipher algorithms, the encrypting key (aka, the public key) could be made public, since (at least for ""high quality"" ciphers) no one without the decrypting key (aka, the private key) could decrypt the message.
In principle, then, the only remaining problem was to be sure that a public key actually belonged to its claimed owner, this is not a problem easy to solve; specially when the two users involved have never met and know nothing about each other.