Box jellyfish

Box jellyfish are cnidarian invertebrates distinguished by their cube-shaped medusae. Some species of box jellyfish produce potent venom: Chironex fleckeri, Carukia barnesi and Malo kingi. Stings from these and a few other species in the class are painful and can be fatal to humans. At least 51 species of box jellyfish were known as of 2018; these are grouped into eight families. A few new species have since been described, it is that additional undescribed species remain. Class Cubozoa Order Carybdeida Family Alatinidae Family Carukiidae Family Carybdeidae Family Tamoyidae Family Tripedaliidae Order Chirodropida Family Chirodropidae Family Chiropsalmidae Family Chiropsellidae The medusa form of a box jellyfish has a squarish, box-like bell, from which its name is derived. From each of the four lower corners of this hangs a short pedalium or stalk which bears one or more long, hollow tentacles; the rim of the bell is folded inwards to form a shelf known as a velarium which restricts the bell's aperture and creates a powerful jet when the bell pulsates.

As a result, box jellyfish can move more than other jellyfish. In the center of the underside of the bell is a mobile appendage called the manubrium which somewhat resembles an elephant's trunk. At its tip is the mouth; the interior of the bell is known as the gastrovascular cavity. It is divided by four equidistant septa into four gastric pockets; the eight gonads are located in pairs on either side of the four septa. The margins of the septa bear bundles of small gastric filaments which house nematocysts and digestive glands and help to subdue prey; each septum is extended into a septal funnel that opens onto the oral surface and facilitates the flow of fluid into and out of the animal. The box jellyfish's nervous system is more developed than that of many other jellyfish, they possess a nerve ring around the base of the bell that coordinates their pulsing movements, a feature found elsewhere only in the crown jellyfish. Whereas some other jellyfish have simple pigment-cup ocelli, box jellyfish are unique in the possession of true eyes, complete with retinas and lenses.

Their eyes are set in clusters called rhopalia, located in pockets halfway up the outer, flat surfaces of the bell. Each contains two rhopalial ocelli with lenses, one directed upwards and the other downwards and inwards towards the manubrium; this enables the animal to see specific points of light, as opposed to distinguishing between light and dark. Box jellyfish have twenty ocelli that do not form images, but detect light and dark. Near the rhopalia are statoliths which detect gravitational pull and help the animal to orient itself. Box jellyfish display complex visually-guided behaviors such as obstacle avoidance and fast directional swimming. Research indicates that, owing to the number of rhopalial nerve cells and their overall arrangement, visual processing and integration at least happen within the rhopalia of box jellyfish; the complex nervous system supports a advanced sensory system compared to other jellyfish, box jellyfish have been described as having an active, fish-like behavior.

A grown box jellyfish can measure up to 20 cm along each box side, the tentacles can grow up to 3 m in length. Its weight can reach 2 kg. There are about 15 tentacles on each corner; each tentacle has about 500,000 cnidocytes, containing nematocysts, a harpoon-shaped microscopic mechanism that injects venom into the victim. Many different kinds of nematocysts are found in cubozoans. Although the notoriously dangerous species of box jellyfish are restricted to the tropical Indo-Pacific region, various species of box jellyfish can be found in tropical and subtropical oceans, including the Atlantic Ocean and the east Pacific Ocean, with species as far north as California, the Mediterranean Sea and Japan, as far south as South Africa and New Zealand, it has been found that the statoliths, which are composed of calcium sulfate hemihydrate, exhibit clear sequential incremental layers, thought to be laid down on a daily basis. This has enabled researchers to estimate growth rates and age to maturity.

Chironex fleckeri, for example, increases its inter-pedalia distance by 3 mm per day, reaching an IPD of 50 mm when 45 to 50 days old. The maximum age of any individual examined was 88 days by which time it had grown to an IPD of 155 mm; the box jellyfish hunts its prey, rather than drifting as do true jellyfish. They are capable of achieving speeds of up to 1.5 to 2 metres per about 4 knots. The venom of cubozoans is distinct from that of scyphozoans, is used to catch prey and for defence from predators, which include the butterfish, rabbitfish and various species of turtle including the hawksbill sea turtle and flatback sea turtle, it seems. Although the box jellyfish has been called "the world's most venomous creature", only a few species in the class have been confirmed to be involved in human deaths, some species pose no serious threat at all. In Australia, fatalities are most caused by the largest species of this class of jellyfish, Chironex fleckeri. Researchers at the University of Hawaii's Department of Tropic

Galois geometry

Galois geometry is the branch of finite geometry, concerned with algebraic and analytic geometry over a finite field. More narrowly, a Galois geometry may be defined as a projective space over a finite field. Objects of study include affine and projective spaces over finite fields and various structures that are contained in them. In particular, ovals, unitals, blocking sets, caps and all finite analogues of structures found in non-finite geometries. Vector spaces defined over finite fields play a significant role in construction methods. Although the generic notation of projective geometry is sometimes used, it is more common to denote projective spaces over finite fields by PG, where n is the "geometric" dimension, q is the order of the finite field GF, which must be an integer, a prime or prime power; the geometric dimension in the above notation refers to the system whereby lines are 1-dimensional, planes are 2-dimensional, points are 0-dimensional, etc. The modifier, sometimes the term projective instead of geometric is used, is necessary since this concept of dimension differs from the concept used for vector spaces.

Having two different concepts with the same name does not cause much difficulty in separate areas due to context, but in this subject both vector spaces and projective spaces play important roles and confusion is likely. The vector space concept is at times referred to as the algebraic dimension. Let V = V denote the vector space of dimension n + 1 defined over the finite field GF; the projective space PG consists of all the positive dimensional vector subspaces of V. An alternate way to view the construction is to define the points of PG as the equivalence classes of the non-zero vectors of V under the equivalence relation whereby two vectors are equivalent if one is a scalar multiple of the other. Subspaces are built up from the points using the definition of linear independence of sets of points. A vector subspace of algebraic dimension d + 1 of V is a subspace of PG of geometric dimension d; the projective subspaces are given common geometric names. The whole space is an n-dimensional subspace and an -dimensional subspace is called a hyperplane.

The number of vector subspaces of algebraic dimension d in vector space V is given by the Gaussian binomial coefficient, q = ⋯ ⋯. Therefore, the number of k dimensional projective subspaces in PG is given by q = ⋯ ⋯. Thus, for example, the number of lines in PG is 2 = = = 35. {\displaysty

Hillcrest Lutheran Academy

Hillcrest Lutheran Academy is a private Christian school in Fergus Falls, Minnesota. Established in 1916, Hillcrest is affiliated with the Church of the Lutheran Brethren of America. Hillcrest's mission is "to equip students in a Christ-centered Bible-based environment for a life of eternal significance." Hillcrest holds accreditation as a non-public high school through Cognia and the Minnesota Nonpublic School Accrediting Association. Hillcrest occupies an historic building constructed in 1901 by the Norwegian Lutheran Synod to house the Park Region Luther College; the four-story red brick and sandstone building, located on a hilltop overlooking the city, is in the Romanesque Revival style and was designed by Twin Cities architects Omeyer and Thori, who designed educational buildings at St. Olaf College, courthouses in Windom and Ada, the E. J. Webber house and Ole Hagen's Autograph Block in Fergus Falls, its construction, supervised by contractor John Lauritzen, required all of the brick masons available in the area.

The building is listed on the National Register of Historic Places. Park Region Luther College operated on the site until 1932, when the synod decided to concentrate its academic efforts on Concordia College in Moorhead. Three years the campus was sold to the Church of the Lutheran Brethren, which operates Hillcrest Academy. Hillcrest served as the high school department of Lutheran Brethren Schools from its founding until 2003, when it was incorporated as a separate school directly under the Church of the Lutheran Brethren, with its own president and school board. HLA continued to share the campus with Lutheran Brethren Seminary, the theological training institute of the Church of the Lutheran Brethren; that was until in 2015, the seminary building was given to Hillcrest, renovated to the new Student Union, the seminary moved across the street to a new addition attached to The Church of the Lutheran Brethren synod offices. Hillcrest won the Minnesota 9-Man State Football Title in 2001 under Head Coach Richard Risbrudt and participating at the state level in basketball and soccer as well.

Coach Risbrudt is enshrined in the Minnesota Highschool Football Coaches Association Hall of Fame. Hillcrest's mascot is Winkey the school colors are red and white. For the last two decades, Hillcrest has had a partnership with the Lutheran high school Danielsen Videregående Skole in Bergen, Norway; each year, 25 to 30 Norwegian students attend Hillcrest as juniors. In recent years, many Korean students have attended HLA as well. Hillcrest has had some notable alumni including former Chief of Chaplains of the United States Army, General Gaylord T. Gunhus. Official Website