It has been estimated that over 20% of the annual gross domestic product in the United States is the result of innovation backed at some point by venture capital investors. But what is innovation? One traditional view of innovation is that it is a systematic business process occurring within an organization required to secure ongoing financial growth. But much of the most acclaimed and influential innovation has started with an individual's idea and only somewhat later followed with an organization to execute on that idea, so the organizational definition is of limited relevance.      A more practical definition of innovation is that it is the creation of anything new intended to be commercialized. Under such a definition, the efforts of a lone individual developing a radical idea and those of a department within a large company to explore a new adjacent market are both examples of innovation. This somewhat loose definition, however, fails to address explicitly what makes an innovation truly new, successful, or authentic, although it may imply that all innovation is equally valid in a sense. Otherwise, the oft-repeated challenge to uses of the term innovation may put too little emphasis on the activity and too much on its results. Quite possibly, 80% of the value of innovation has been contributed by 20% of the activity, but whether that 20% of activity could have manifested itself without a culture and economy to support the whole is less clear. In this regard, policy- and strategy-oriented attempts to refine this loose definition of innovation further are without merit.    

     The study of climate change has established retreating glaciers and rising global temperatures from a number of data sources. Establishing the influence of mankind upon these effects has been more difficult, because the climate is subject to oscillations that are much longer in duration than our record of direct temperature measurements, which extends back only about 150 years.      By drilling and conducting chemical and physical studies of ice cores on six of the seven continents, scientists have developed a method of estimating climatic information that had previously been thought inaccessible. Ice cores removed from the earth's crust and studied in order to draw such inferences are termed paleo-proxies. The values of various climatic variables at a particular time and place can be inferred through some form of proxy analysis in a given ice core sample. For example, deuterium excess indicates humidity levels, electrical conductivity indicates volcanic activity, beryllium levels indicate solar activity, and particle size and concentration indicate wind speeds. Temperature, in particular, can be inferred from the ratios of water molecules composed of stable isotopes of oxygen and hydrogen, namely 1H2H16O and 1H218O. Because molecules consisting of these isotopes have slightly different weights than their more common counterparts, their concentration in the ice core in a given epoch depends on the condensation temperature prevailing at the time. This technique enables scientists to estimate the air temperature of condensation when the snow fell and establish variations in temperature over a series of multiple samples.      One advantage of using ice cores as a paleo-proxy is that ice core samples can be extracted from across the world using different drilling techniques, for analysis either on-site or in a laboratory, with results that can be compared to each other and stitched into a coherent global picture. The primary sources of ice cores are the ice sheets of Antarctica and Greenland, whose thickness allows scientists to extract long cores representing time spans of up to 100,000 or even 400,000 years. Nevertheless, samples representing spans of multiple centuries have been extracted more recently at low latitudes--for example, at Mt. Kilimanjaro, in the Andes Mountains, and on the Himalayan plateau. Depending on the objectives of the project and the nature of the ice core, scientists use a variety of types of drill ranging from hand-powered auger drill to electro-mechanical drills. A limitation of using ice cores is that they represent data for conditions during snowfall only. Periods bereft of snowfall will fail to leave a record in the ice and can even disrupt the essential step of dating the samples. To mitigate this problem, multiple cores are typically extracted from nearby locations. A more critical limitation of the ice core method, one indicative of the larger problem at hand, is that as ice fields continue to retreat, the ability to measure in some locations will disappear entirely.  

     The diversity of species in bacterial communities is often studied by phenotypic characterization. A problem with this method is that phenotypic methods can be used only on bacteria which can be isolated and cultured, and most soil bacteria that have been observed by fluorescence microscope cannot be isolated and cultured.     DNA can be isolated from bacteria in soil to obtain genetic information about the nonculturable bacteria therein. The heterogeneity of this DNA is a measure of the total number of genetically different bacteria, or the number of species. DNA heterogeneity can be determined by thermal denaturation and reassociation. In general, renaturation of homologous single-stranded DNA follows second-order reaction kinetics. In other words, the fraction of DNA that has renatured within a given time period is proportional to the genome size or the complexity of DNA, defined as the number of nucleotides in the DNA of a haploid cell, without repetitive DNA. The genetic diversity of a bacterial community can be inferred in a similar manner.     Vigdis Torsvik, Jostein Goksyr, and Frida Lise Daae used this process to analyze soil samples taken from the soil from a beech forest north of Bergen, Norway. The reassociation curves for the main DNA fraction did not follow ideal second-order reaction kinetics, so the half-life values gave only approximate, underestimated values for the number of genomes present. Nevertheless, the soil bacterium DNA was very heterogeneous; the diversity corresponded to about 4,000 distinct genomes of a size typical of standard soil bacteria. This diversity was about 200 times as many species as could have been isolated and cultured.     Various procedures for isolating DNA from river sediments and seawater are known. This opens up the possibility of applying the thermal denaturation method to systems other than soil. The results of the Norway study indicated that the genetic diversity of the total bacterial community in a deciduous-forest soil is so high that heterogeneity can be determined only approximately. In environments with pollution or extreme conditions, the genetic diversity might be easier to determine precisely.  

     How aquatic vertebrates evolved into land vertebrates has been difficult for evolutionary biologists to study, in part because the shift from water to land appears to have occurred rapidly and has thus has yielded a scarce fossil record. Prior to the advent of DNA sequencing, the primary guideposts in tracing the emergence of tetrapods had been morphological considerations, which highlighted the coelacanth and the lungfish as species of interest.      Coelacanths and lungfish are distinct from other fish in that they are lobe-finned species. Lobe-finned species, like ray-finned fishes such as tuna and trout, possess not cartilage but a bony skeleton, a key prerequisite for survival on land. Lobe-finned fish species are distinguished from ray-finned species by fins that are joined to a single bone, and which thus have the potential to evolve into limbs. Coelacanths and lungfish are two of the only lobe-finned species that are not extinct, and since they have evolved minimally since the time of the appearance of tetrapods, they are sometimes referred to as "living fossils." In fact, the first live coelacanth was discovered more than 100 years after the species had been discovered in fossilized form.      Whether the coelacanth in particular is rightly called a living fossil and whether it is the closest living relative of the original tetrapods are two questions that have been illuminated recently by genetic analysis. The coelacanth's sequenced genome, and this analysis has led to the conclusion that the lungfish is the closer relative of tetrapods. Moreover, coelacanth DNA has shown evolution over time, although at a rate much slower than that of most animals. The fish's morphology and its environment deep in the Indian Ocean may have created favorable conditions, allowing a more slowly evolving species to have survived for the last 400 million years.    

     Physical theory implies that the existence of astronomical entities above a certain mass is evidence for the existence of black holes. The Earth does not itself collapse upon itself under gravitational force because gravity is countered by the outward pressure generated by the electromagnetic repulsion between the atoms making up the planet. But if these forces are overpowered, gravity will always lead to the formation of a black hole. Assuming the validity of general relativity, we can calculate the upper bound for a star, the Tolman-Oppenheimer-Volkoff limit, to be 3.6 solar masses; any object heavier than this will be unable to resist collapse under its own mass and must be a black hole.     The search for entities more massive than the Tolman-Oppenheimer-Volkoff limit brings us to the examination of X-ray binary systems. In an X-ray binary, two bodies rotate around their center of mass, a point between them, while one component, usually a normal star, sheds matter to the other more massive component known as the accretor. The shedding matter is released as observable X-ray radiation. Since binary stars rotate around a common center of gravity, the mass of the accetor can be calculated from the orbit of the visible one. By 2004, about forty X-ray binaries that contained candidates for black holes had been discovered. The accretors in these binary systems did not appear visible, as is to be expected of black holes, but that fact alone does not distinguish them from very dense and hence less luminescent stars, such as neutron stars. More to the point is that these accretors were of mass far in excess of 3.6 solar masses. Famously, Cygnus X-1, an X-ray binary in the constellation Cygnus, has an accretor whose mass has been calculated to be 14 solar masses, plus or minus 4 solar masses. While it does not rule out other phenomena without further interpretation, it provides strong proof that black holes exist.     The conclusion that black holes exist depends on the reliability of the general-relativistic calculations involved. If more generous assumptions are made, the Tolman-Oppenheimer-Volkoff limit can be calculated to be as high as 10 solar masses. The finding also establishes plausibility, if not direct evidence, for the existence of supermassive black holes hypothesized to exist at the center of some galaxies.  

     In the realm of the psychology of decision-making, the role of expert intuition is under attack. People's inclination is to trust intuition and to point to many examples, across various disciplines, in which experts are able to make difficult judgments in seemingly negligible amounts of time. But this trust of intuition has been undermined by the research of other psychologists who have taken care to expose and document thoroughly the cognitive biases that can impede both our use of intuition and our ability to judge the use of intuition in a broader sense. How, then, can we know when expert intuition is to be trusted?      Gary Klein's research has provided a basis on which to establish how expert intuition, also known as naturalistic decision making, works at its best, which it does according to a recognition-primed decision model. One of his studies examined the thought process of experienced fireground commanders, the leaders of firefighter teams. One finding was that fireground commanders do not only consider a small number of options in deciding how to approach a firefighting situation; they tend to consider only one option. When presented with a situation, the commander was observed to think of one option spontaneously and then mentally simulate acting on that proposed course of action to see whether it would work. More specifically, Klein formulated the recognition-primed decision model as occurring in two steps. In the first step, a tentative plan comes to the mind of the expert by an automatic function of associative memory; the situation provides one or more clues recognized by the expert. Second, the plan is mentally simulated to see whether it will work.      When, then, can expert intuition be tested? Klein's model implies that the successful application of expert intuition will be limited to circumstances in which situational clues are reproduced and can be recognized over time. Situational regularity and individual memory are critical components of success. Reliable intuition is primarily — and, arguably, nothing more than — recognition. By this somewhat controversial inference, intuition is essentially memory. Consequently, all cases in which we might anticipate expert intuition to be valid are not equally conquerable by this faculty. Some environments may not be sufficiently regular to be predictable, and, of course, even in regular environments, the presumed expert must draw on a sufficient depth of practice. We can conclude, for example, that if a dedicated stock picker is to make judgments as skilled as those of a dedicated chess player, that person will do so not by relying primarily on intuition. One might note that, with or without intuition, it is incumbent on any true expert to know the limits of his or her knowledge.    

     Birds of various species, from pigeons to swallows to larger birds, can navigate long distances on Earth, across continents and hemispheres. That they can traverse these distances thanks to a magnetic sense has been demonstrated through tests in which birds fitted with magnets have lost their navigational capability. Precisely what biological mechanism enables birds to orient in this way is still something of a mystery, however, with two theories prevailing.      One theory is that birds possess magnetic sensors in the form of grains of magnetite, which is an easily magnetized form of iron oxide. Such magnetite grains are common not only in animals but even in bacteria, where they have been established as a component enabling magnetic orientation. In the case of birds, magnetite grains are numerous in beaks, as dissections of pigeons have confirmed. Moreover, in another experiment, the trigeminal nerve, which connects the beak to the brain, was severed in reed warblers; the affected birds lost their sense of magnetic dip, which is critical to navigation.      Critics of the theory have pointed out that the abundance of grains in the beak are not concentrated, as would be expected in a sensory organ, but rather found in wandering macrophages. And while an alternative explanation for birds' sensory abilities might posit magnetite grains outside of the beak, such an explanation would be supported neither by the beak dissections nor by the tests of severed trigeminals. Critics of magnetite-centric theories suggest a second theory: that the magnetic field of the Earth has an influence on a chemical reaction in birds, specifically in a bird's retina. Experiments have demonstrated that destroying the portion of a robin's retina known as cluster N eliminates the bird's ability to detect north. Birds' eyes do not contain magnetite grains, however. Rather, some advocates of the theory that birds navigate by retinal interaction believe that a retinal protein known as cryptochrome processes magnetic information within the cluster N. Surprisingly, the mechanism by which cryptochrome could detect magnetic orientation depends on quantum mechanics: when hit by light, the cryptochrome would create a pair of particles, one of which subsequently presents information to the eye, in the form of a spot, when it is triggered a corresponding particle after that particle has traveled some distance.