Mountain pass

A mountain pass is a route through a mountain range or over a ridge. If following the lowest possible route, a pass is locally the highest point on that route. Since many of the world's mountain ranges have presented formidable barriers to travel, passes have been important since before recorded history, and have played a key role in trade, war, and migration. At lower elevations it may be called a hill pass. The highest pass is Thorong La, located in the Damodar Himal, north of the Annapurna range, Nepal.

Overview

Mountain passes make use of a gap, saddle or col (also sometimes a notch, the low point in a ridge). A topographic saddle is analogous to the mathematical concept of a saddle surface, with a saddle point marking the highest point between two valleys and the lowest point along a ridge. On a topographic map, passes are characterized by contour lines with an hourglass shape, which indicates a low spot between two higher points.

Passes are often found just above the source of a river, constituting a drainage divide. A pass may be very short, consisting of steep slopes to the top of the pass, or may be a valley many kilometres long, whose highest point might only be identifiable by surveying.

Reading (legislature)

A reading of a bill is a debate on the bill held before the general body of a legislature, as opposed to before a committee or other group. In the Westminster system, there are usually several readings of a bill among the stages it passes through before becoming law as an Act of Parliament. Some of these readings are usually formalities rather than substantive debates.

First reading

A first reading is when a bill is introduced to a legislature. Typically, in the United States, the title of the bill is read and immediately assigned to a committee. The bill is then considered by committee between the first and second readings. In the United States Senate and most British-influenced legislatures, the committee consideration occurs between second and third readings.

In Ireland, the first reading is referred to as "First Stage" and is leave to introduce a bill into a House of the Oireachtas. It may be taken in either house, but it does not need to be taken in both.

In New Zealand, once a bill passes first reading it is normally referred to a Select Committee. However, a Government can have a bill skip the select committee stage by a simple majority vote in Parliament.

Pass (military)

A pass is permission to be away from one's military unit for a limited period of time. Time away on a pass is not counted against leave, the annual allotment of days off from duty.

Types of passes

By country variations

In the RAF, a "Permanent Pass" known as Form 557 would be issued to servicemen of good standing and six-months service allowing them to leave the quarters after duty until midnight and no further than eight miles (or as otherwise restricted on the form). It could be endorsed with permission to wear plain clothes.

Helix

A helix (pl: helixes or helices) is a type of smooth space curve, i.e. a curve in three-dimensional space. It has the property that the tangent line at any point makes a constant angle with a fixed line called the axis. Examples of helices are coil springs and the handrails of spiral staircases. A "filled-in" helix – for example, a spiral ramp – is called a helicoid. Helices are important in biology, as the DNA molecule is formed as two intertwined helices, and many proteins have helical substructures, known as alpha helices. The word helix comes from the Greek word ἕλιξ, "twisted, curved".

Types

Helices can be either right-handed or left-handed. With the line of sight along the helix's axis, if a clockwise screwing motion moves the helix away from the observer, then it is called a right-handed helix; if towards the observer, then it is a left-handed helix. Handedness (or chirality) is a property of the helix, not of the perspective: a right-handed helix cannot be turned to look like a left-handed one unless it is viewed in a mirror, and vice versa.

Phelix

Phelix is a high-speed stream cipher with a built-in single-pass message authentication code (MAC) functionality, submitted in 2004 to the eSTREAM contest by Doug Whiting, Bruce Schneier, Stefan Lucks, and Frédéric Muller. The cipher uses only the operations of addition modulo 2³², exclusive or, and rotation by a fixed number of bits. Phelix uses a 256-bit key and a 128-bit nonce, claiming a design strength of 128 bits. Concerns have been raised over the ability to recover the secret key if the cipher is used incorrectly.

Performance

Phelix is optimised for 32-bit platforms. The authors state that it can achieve up to eight cycles per byte on modern x86-based processors.

FPGA Hardware performance figures published in the paper "Review of stream cipher candidates from a low resource hardware perspective" are as follows:

Helix

Phelix is a slightly modified form of an earlier cipher, Helix, published in 2003 by Niels Ferguson, Doug Whiting, Bruce Schneier, John Kelsey, Stefan Lucks, and Tadayoshi Kohno; Phelix adds 128 bits to the internal state.

Helix (multimedia project)

Helix DNA is a project to produce computer software that can play audio and video media in various formats, aid in producing such media, and serve them over a network. It is intended as a largely free and open source digital media framework that runs on numerous operating systems and processors (including mobile phones) and was started by RealNetworks which contributed much of the code. The Helix Community is an open collaborative effort to develop and extend the Helix DNA platform.

Helix DNA Client is a software package for multi-platform multi-format media playback. Helix Player is a media player that runs on Linux, Solaris, Symbian and FreeBSD and uses the Helix DNA Client. The Helix DNA Producer application aids in the production of media files, and Helix DNA Server can stream media files over a network.

Licenses

The code is released in binary and source code form under various licenses, notably the proprietary RealNetworks Community Source License and the free and open source software RealNetworks Public Source License. Additionally, the Helix DNA Client and the Helix Player are licensed under the popular GNU General Public License (GPL) free and open source license.

Silo (library)

Silo is a computer data format and library developed at Lawrence Livermore National Laboratory (LLNL) for storing rectilinear, curvilinear, unstructured, or point meshes in 2D and 3D. It supports data upon those meshes, including scalar, vector, and tensor variables; volume fraction-based materials; and mass fraction-based species. It fully supports block structured adaptive mesh refinement (AMR) meshes by way of mesh blocks structured in a hierarchy. Silo sits on top of other low-level storage libraries such as PDB, NetCDF, and HDF5.

Currently, VisIt, an open source software package with its start at LLNL, supports the Silo format for visualization and analysis, among many other formats.

As of Version 4.8, July, 2010, the Silo source code is now available under the standard BSD Open Source License.

The source code for two compression libraries which have been part of previous releases of the Silo library is not available under the terms of the BSD Open Source license. These are the Hzip and FPzip compression libraries.