Bluetooth low energy

On June 12, 2007, Nokia and Bluetooth SIG announced that Wibree will be a part of the Bluetooth specification, being an ultra-low power Bluetooth technology.Expected use cases include watches displaying Caller ID information, sports sensors monitoring your heart rate during exercise, plus medical devices. The Medical Devices Working Group is also creating a medical devices profile and associated protocols to enable this market. Battery life for devices using Bluetooth low energy technology is designed to last up to one year.

IPv6 private addresses

Just as IPv4 reserves addresses for private or internal networks, there are blocks of addresses set aside in IPv6 for private addresses. In IPv6, these are referred to as unique local addresses (ULA). RFC 4193 sets aside the routing prefix fc00::/7 for this block. The addresses include a 40-bit pseudorandom number that minimize the risk of address collisions if sites merge or packets are misrouted.

Early designs (RFC 3513) used a different block for this purpose (fec0::), dubbed site-local addresses. However, the definition of what constituted "sites" remained unclear, and the poorly defined address structure created ambiguities for routing. The address range specification was abandoned and must no longer be used in new systems.

Addresses starting with fe80: — called link-local addresses — are routable only in the local link area. The addresses are assigned automatically by the operating system's IP layer for each network interface. This provides instant network connectivity for any IPv6 host and means that if several hosts connect to a common hub or switch, they have an instant communication path via their link-local IPv6 address.

Kinesthetic sense

Proprioception, the kinesthetic sense, provides the parietal cortex of the brain with information on the relative positions of the parts of the body. Neurologists test this sense by telling patients to close their eyes and touch the tip of a finger to their nose. Assuming proper proprioceptive function, at no time will the person lose awareness of where the hand actually is, even though it is not being detected by any of the other senses. Proprioception and touch are related in subtle ways, and their impairment results in surprising and deep deficits in perception and action.

Pillbox

Dug-in guard posts (with loopholes through which to fire guns) and made from concrete are also known as 'pillboxes'. The originally jocular name arose from their perceived similarity to the cylindrical boxes in which medical pills were once sold.They are in effect a trench firing step hardened to protect against small-arms fire and grenades and raised to improve the field of fire.

Their use seems to have developed during the period of the First World War when defence in depth using the Machine Gun Corps was being perfected. However, most of those seen in Britain, having been left over from the 1940 invasion scare, are designed for use by riflemen rather than for machine gunners. The concrete nature of pillboxes means that they are a feature of prepared positions and their original use is likely to have been in the Hindenburg Line. This is likely to have been the time when they acquired their incongruous English name. The Oxford English Dictionary's earliest record of the use of the word pillbox in connection with a defensive post is from 13 September 1917, after the German withdrawal onto the Hindenburg Line.


Pillboxes are often camouflaged in order to conceal their location and to maximize the element of surprise. They may be part of a trench system, form an interlocking line of defence with other pillboxes by providing covering fire to each other (defence in depth), or they may be placed to guard strategic structures such as bridges and jetties.


Many pillboxes were built before WWII in the Czech Republic in defence against the German invasion of Czechoslovakia. None of these were actually used in the end, since the German military met no resistance when invading the country because it was effectively forced to capitulate as a result of Allies annexing the country's border areas and handing them to Germany. The Japanese also made use of pillboxes in their fortifications of Iwo Jima.

Human-computer interaction

Human–computer interaction (HCI) is the study of interaction between people (users) and computers. It is often regarded as the intersection of computer science, behavioral sciences, design and several other fields of study. Interaction between users and computers occurs at the user interface (or simply interface), which includes both software and hardware, for example, general-purpose computer peripherals and large-scale mechanical systems, such as aircraft and power plants. The following definition is given by the Association for Computing Machinery

"Human-computer interaction is a discipline concerned with the design, evaluation and implementation of interactive computing systems for human use and with the study of major phenomena surrounding them."

Because human-computer interaction studies a human and a machine in conjunction, it draws from supporting knowledge on both the machine and the human side. On the machine side, techniques in computer graphics, operating systems, programming languages, and development environments are relevant. On the human side, communication theory, graphic and industrial design disciplines, linguistics, social sciences, cognitive psychology, and human performance are relevant. Engineering and design methods are also relevant. Due to the multidisciplinary nature of HCI, people with different backgrounds contribute to its success. However, due to the different value systems of its diverse members, the collaboration can be challenging