Measurement of feature clustering in images

Author(s):  
John C. Russ

The spatial distribution of features in an image is often interesting, but not simple to characterize. Mapping of the image into a different space (e.g., Fourier or Hough) offers direct information on various regularities in feature spacing or alignment, but does not deal directly with the individual features. Two other approaches are available; each has advantages and drawbacks, which are discussed here.Schwarz & Exner determine the spatial coordinates of the centroids of features, and sort them to locate the nearest neighbor for each feature present, constructing a distribution plot of the frequency of nearest neighbor distances. Figures 1 and 2 show an example. The three fields in Figure 1 contain, respectively, features which are well-spaced from each other, randomly arranged on the plane, and clustered together. For the random distribution of points, the histogram of nearest neighbor distances is a Poisson distribution, and the mean value is 0.5/NA1/2, where NA is the number of features divided by the area of the image.

1974 ◽  
Vol 75 (2) ◽  
pp. 274-285 ◽  
Author(s):  
A. Gordin ◽  
P. Saarinen ◽  
R. Pelkonen ◽  
B.-A. Lamberg

ABSTRACT Serum thyrotrophin (TSH) was determined by the double-antibody radioimmunoassay in 58 patients with primary hypothyroidism and was found to be elevated in all but 2 patients, one of whom had overt and one clinically borderline hypothyroidism. Six (29%) out of 21 subjects with symptomless autoimmune thyroiditis (SAT) had an elevated serum TSH level. There was little correlation between the severity of the disease and the serum TSH values in individual cases. However, the mean serum TSH value in overt hypothyroidism (93.4 μU/ml) was significantly higher than the mean value both in clinically borderline hypothyroidism (34.4 μU/ml) and in SAT (8.8 μU/ml). The response to the thyrotrophin-releasing hormone (TRH) was increased in all 39 patients with overt or borderline hypothyroidism and in 9 (43 %) of the 21 subjects with SAT. The individual TRH response in these two groups showed a marked overlap, but the mean response was significantly higher in overt (149.5 μU/ml) or clinically borderline hypothyroidism (99.9 μU/ml) than in SAT (35.3 μU/ml). Thus a normal basal TSH level in connection with a normal response to TRH excludes primary hypothyroidism, but nevertheless not all patients with elevated TSH values or increased responses to TRH are clinically hypothyroid.


2011 ◽  
Vol 25 (12n13) ◽  
pp. 1041-1051 ◽  
Author(s):  
HO KHAC HIEU ◽  
VU VAN HUNG

Using the statistical moment method (SMM), the temperature and pressure dependences of thermodynamic quantities of zinc-blende-type semiconductors have been investigated. The analytical expressions of the nearest-neighbor distances, the change of volumes and the mean-square atomic displacements (MSDs) have been derived. Numerical calculations have been performed for a series of zinc-blende-type semiconductors: GaAs , GaP , GaSb , InAs , InP and InSb . The agreement between our calculations and both earlier other theoretical results and experimental data is a support for our new theory in investigating the temperature and pressure dependences of thermodynamic quantities of semiconductors.


2019 ◽  
Author(s):  
Kathryn Nicole Graves ◽  
James Antony ◽  
Nicholas Turk-Browne

While navigating the world, we pick up on patterns of where things tend to appear. According to theories of memory and studies of animal behavior, knowledge of these patterns emerges gradually over days or weeks, via consolidation of individual navigation episodes. Here we discover that navigation patterns can also be extracted online, prior to the opportunity for offline consolidation, as a result of rapid statistical learning. Human participants navigated a virtual water maze in which platform locations were drawn from a spatial distribution. Within a single session, participants increasingly navigated through the mean of the distribution. This behavior was better simulated by random walks from a model with only an explicit representation of the current mean, compared to a model with only memory for the individual platform locations. These results suggest that participants rapidly summarized the underlying spatial distribution and used this statistical knowledge to guide future navigation.


2019 ◽  
Vol 30 (4) ◽  
pp. 968-974 ◽  
Author(s):  
Alexander D M Wilson ◽  
Alicia L J Burns ◽  
Emanuele Crosato ◽  
Joseph Lizier ◽  
Mikhail Prokopenko ◽  
...  

Abstract Animal groups are often composed of individuals that vary according to behavioral, morphological, and internal state parameters. Understanding the importance of such individual-level heterogeneity to the establishment and maintenance of coherent group responses is of fundamental interest in collective behavior. We examined the influence of hunger on the individual and collective behavior of groups of shoaling fish, x-ray tetras (Pristella maxillaris). Fish were assigned to one of two nutritional states, satiated or hungry, and then allocated to 5 treatments that represented different ratios of satiated to hungry individuals (8 hungry, 8 satiated, 4:4 hungry:satiated, 2:6 hungry:satiated, 6:2 hungry:satiated). Our data show that groups with a greater proportion of hungry fish swam faster and exhibited greater nearest neighbor distances. Within groups, however, there was no difference in the swimming speeds of hungry versus well-fed fish, suggesting that group members conform and adapt their swimming speed according to the overall composition of the group. We also found significant differences in mean group transfer entropy, suggesting stronger patterns of information flow in groups comprising all, or a majority of, hungry individuals. In contrast, we did not observe differences in polarization, a measure of group alignment, within groups across treatments. Taken together these results demonstrate that the nutritional state of animals within social groups impacts both individual and group behavior, and that members of heterogenous groups can adapt their behavior to facilitate coherent collective motion.


2012 ◽  
Vol 15 (2) ◽  
pp. 253-257 ◽  
Author(s):  
R. Popielarczyk ◽  
S. Robak ◽  
K. Siwicki

Infection of European eel, Anguilla anguilla (L.), with the nematode Anguillicoloides crassus (Kuwahara, Niimi et Itagaki, 1974) in Polish waters The aim of this study was to determine the degree of Anguillicoloides crassus infection in European eel inhabiting Polish waters based on selected parasitic descriptors and on anatomical pathology of the swimbladder using macroscopic methods. In all, 154 European eel specimens were sampled from eleven sites in Poland and A. crassus was present in the swimbladder of 114 fish. The intensity of A. crassus infection in all the eel specimens ranged from 1 to 62 parasites at a mean value of 7.5. High values of mean infection intensity were noted in samples from Pomeranian lakes Bukowo, Łebsko, and Jamno. The health of the swimbladder was evaluated using the swimbladder degenerative index (SDI). The mean value of the SDI for all of the eel examined was 3.3, and extensively degenerated swimbladders were observed mainly in samples in the Szczecin Lagoon and from lakes. According to the individual SDI ratings, 9.1% of the eel specimens did not exhibit pathological symptoms of the swimbladder (SDI-0) and an extremely damaged (SDI-6) swimbladder was noted in 11.7% of the fish examined. In the case of eel infected with A. crassus, higher SDI values were reflected in initially increasing shares in subsequent categories. In fish that were not infected with the nematode, only 20% (8 individuals) of the swimbladders showed no symptoms of pathology (SDI-0).


1976 ◽  
Vol 54 (8) ◽  
pp. 688-698 ◽  
Author(s):  
J. R. Percy ◽  
M. E. Percy ◽  
R. Baumal

A mathematical model, based on second-order reaction kinetics, has been used to describe the covalent assembly of immunoglobulin G (IgG) in vitro from its heavy (H) and light (L) chains (Percy, M. E., Baumal, R., Dorrington, K. J. &Percy, J. (1976) Can. J. Biochem. 54, 675–687). In the present paper, the same model has now been applied to the steady-state assembly of IgG in vivo. This mathematical approach permits a quantitative comparison of the pathways of covalent assembly used by given immunoglobulins in vivo and in vitro. The assumptions in the model are: the species L, H, HL, HH, HHL and LHHL belong to a common pool; incompleted IgG intermediates may freely assemble to form HL, HH, HHL and LHHL; the reaction rate for covalent linkage between any two reacting species is proportional to the products of the number densities of the reactants and to a parameter P which takes the value PHH if the reaction joins two H chains, and PHL if it joins an H and L chain. In vivo values of PHH/PHL were determined for the 18 mouse myeloma tumours and cell lines studied by Baumal et al. (Baumal, R., Potter, M. &Scharff, M. (1971) J. Exp. Med. 134, 1316–1334). From these analyses, we have arrived at the following conclusions: (1) the three major IgG subclasses have distinctive values of PHH/PHL (mean value 53 for IgG1, 12 for IgG2a and 2.8 for IgG2b); (2) for IgGs of the same subclass, the values of PHH/PHL are similar; (3) the mean in vivo values of PHH/PHL are very close to those determined from in vitro assembly experiments. Finally, the individual values of PHH/PHL have been used to simulate pulse-chase experiments in the various tumours and cell lines. Considering the sources and magnitude of experimental error, the theoretical pathways of assembly agree with those determined qualitatively from the pulse-chase experiments.


2020 ◽  
Vol 31 (9) ◽  
pp. 1183-1190 ◽  
Author(s):  
Kathryn N. Graves ◽  
James W. Antony ◽  
Nicholas B. Turk-Browne

While navigating the world, we pick up on patterns of where things tend to appear. According to theories of memory and studies of animal behavior, knowledge of these patterns emerges gradually over days or weeks via consolidation of individual navigation episodes. Here, we discovered that navigation patterns can also be extracted on-line, prior to the opportunity for off-line consolidation, as a result of rapid statistical learning. Thirty human participants navigated a virtual water maze in which platform locations were drawn from a spatial distribution. Within a single session, participants increasingly navigated through the mean of the distribution. This behavior was better simulated by random walks from a model that had only an explicit representation of the current mean, compared with a model that had only memory for the individual platform locations. These results suggest that participants rapidly summarized the underlying spatial distribution and used this statistical knowledge to guide future navigation.


1932 ◽  
Vol 16 (1) ◽  
pp. 65-73 ◽  
Author(s):  
Pei-Sung Tang

The rate of anaerobic production of CO2 by germinating seeds of Lupinus albus was studied as a function of temperature between 7.5° and 18°C. The mean value for the temperature characteristic was found to be 21,500± calories, which is slightly lower than that for the same process under aerobic conditions (23,500± calories). The values for the individual µ's in the two cases overlap considerably. The possible identity of the processes underlying the production of CO2 aerobically and anaerobically is discussed.


1977 ◽  
Vol 9 (3) ◽  
pp. 281-289 ◽  
Author(s):  
T. Pentikäinen

Several “short cut” methods exist to approximate the total amount of claims ( = χ) of an insurance collective. The classical one is the normal approximationwhere and σx are the mean value and standard deviation of x. Φ is the normal distribution function.It is well-known that the normal approximation gives acceptable accuracy only when the volume of risk business is fairly large and the distribution of the amounts of the individual claims is not “too dangerous”, i.e. not too heterogeneous (cf. fig. 2).One way to improve the normal approximation is the so called NP-method, which provides for the standardized variable a correction Δzwhereis the skewness of the distribution F(χ). Another variant (NP3) of the NP-method also makes use of the moment μ4, but, in the following, we limit our discussion mainly to the variant (2) (= NP2).If Δz is small, a simpler formulais available (cf. fig. 2).Another approximation was introduced by Bohman and Esscher (1963). It is based on the incomplete gamma functionwhere Experiments have been made with both formulae (2) and (4); they have been applied to various F functions, from which the exact (or at least controlled) values are otherwise known. It has been proved that the accuracy is satisfactory provided that the distribution F is not very “dangerous”.


1963 ◽  
Vol 61 (3) ◽  
pp. 341-348 ◽  
Author(s):  
I. H. Bath ◽  
J. A. F. Rook

1. A study was made of the effects of feeding regimen and the composition of the diet on the ruminal production of V.f.a.'S in cattle.2. The day-to-day variations in the pattern of rumen fermentation in cows given a diet of hay and concentrates indicated that within-cow differences in the molar proportions of the acids from diet to diet are of significance if they exceed about 3% (of the mean value) for acetic acid, about 10% for propionic and butyric acids, and about 25% for valeric acid. The results emphasized also the important differences to be found between cows given the same diet.3. A change in the frequency of feeding from once to four times daily at a constant daily drymatter intake had little effect on the daily mean values for pH, concentration of total V.f.a.'S, or the molar percentages of the individual acids, but almost invariably decreased the range of values observed between feeding.4. With diets of hay and of hay and concentrates an increase in daily dry-matter intake was associated with a fall in pH and an increase in the concentration of total V.f.a.'S; with the diet of hay and concentrates there was a considerable decrease in the molar percentage of acetic acid and a corresponding increase in N-butyric, but there was little change in the molar percentages of the acids with the diet of hay.


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