Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Migration”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,405 records · Page 78Linked to original sources
PubMed1998

Postoperative migration of the osteotomy segment stabilized by titanium miniplate osteosynthesis following Le Fort I osteotomy: an x-ray stereometric study.

The aim of the present study was to evaluate whether titanium miniplate fixation prevents postoperative migration of the osteotomy segment following Le Fort I osteotomy and, if not, to evaluate whether postoperative migration varies with the direction and amount of surgical repositioning. In 10 consecutive patients who received Le Fort I osteotomies, postoperative migration of the osteotomy segment was studied in a three-dimensional system by means of x-ray stereometry. Surgical repositioning was recorded by cephalometry in lateral head films obtained before surgery and at 2 days postoperatively. X-ray stereograms were obtained at intervals from 2 days to 1 year after surgery. During the 1-year observation period, significant postoperative migration of the osteotomy segment was found at some stage in nine patients. No correlation between the amount of surgical repositioning and postoperative migration was found. However, a tendency toward superiorly directed postoperative migration of the osteotomy segment, independent of the direction of surgical repositioning, was observed. It is thus concluded that titanium miniplates do not prevent postoperative migration of the osteotomy segment. The weak correlation between the amount of surgical repositioning and postoperative migration of the osteotomy segment indicates that predictions of individual outcomes of surgical corrections are uncertain.

Adolescent↗
PubMed1988

Labour migration as a response to relative deprivation.

The relationship between labor migration and relative deprivation is examined. "We model migration from one reference group to another as a response to relative deprivation and satisfaction: We say that a strong incentive to migrate exists if relative deprivation decreases while satisfaction rises with migration and that a weak incentive exists if the individual increases or decreases his satisfaction and deprivation at the same time by migrating. We derive conditions under which different incentives, weak or strong, hold for different individuals.... Our analysis enables us to explain several perplexing migratory phenomena, identify income inequality as a distinct explanatory variable of migration and establish an incentive to migrate in situations where the utility-social welfare approach does not."

Behavior↗
PubMed1978

An economic analysis of migration in Mexico.

This paper analyzes internal migration in Mexico over the 1960-70 period. A model of the determinants of migration is specified and estimated for aggregated interstate migration flows. Results show that distance serves as a significant deterrent to migration, that higher destination earning levels are attractive to migrants, and that regions with high unemployment rates experience lower rates of inmigration. An unanticipated finding is that regions with higher earning levels have greater rates of outmigration. The data are disaggregated to examine separate migration relationships for each state. The results are that distance is a lesser deterrent for those migrants with more accessible alternatives, that higher earning levels reduce the deterring effects of distance, and that regions with higher earning levels have lower associated elasticities of migration. It is concluded that economic factors have played a crucial role in internal migration and thus in the changing occupational and geographic structure of the Mexican labor force.

Americas↗
PubMed1975

[A simplified macrophage migration inhibition test to measure T-cell derived immunity in man].

A macrophage migration inhibition test using heterologous cells (DMMTH) is performed in an agarose-droplet technique. A suspension consisting of peritoneal exsudate cells from Guinea pig and human lymphocytes, mixed with 0,2 percent agarose is dispensed in droplets with a dispenser into culture chambers used for the leukocyte migration inhibition test. Macrophages migrate out of the gelified droplets. Migration areas can be measured by planimetry. Migration areas are exact to 8.6 percent. A significant migration inhibition, caused by migration inhibitory factors is observed after the reaction of the specific antigen with sensitized lymphocytes in the agarose droplet. The sensitivity of the test has been demonstrated in Mantoux positive persons.

Cell Migration Inhibition↗
PubMed1993

Trade, aid and migrations: some basic policy issues.

The link between trade policy and international migration is explored using data from the United States and Europe. "We conclude that restrictive trade policies in industrialised countries have most likely added to migration pressures. We then turn to the broader question of the effects of income growth in the sending countries on the propensity to migrate. We argue that, in relatively poor countries, an increase in income will be associated with higher migration flows. For middle income countries, however, income growth will lead to lower migrations. In the medium run, therefore, the relationship between development levels, as measured by GDP per capita, and the propensity to migrate follows an inverse-U pattern. Econometric analysis of aggregate migration flows from Southern Europe provides considerable support for such conjecture."

Americas↗
PubMed1982

Migration inhibition of normal rat thymocytes as an in vitro method for detecting cell-mediated immunity in rat and mouse.

Normal rat thymocytes were used as a migrating population to study the effect of migration inhibition factor (MIF) released by sheep red blood cell (SRBC) immune lymphocytes. Normal thymocytes (migrating cells), SRBC (target antigen) and SRBC immune lymphocytes (effector cells) were packed in capillary tubes and their migration studied. This migration inhibition assay proved to be a very good in vitro correlate of specific delayed type hypersensitivity against SRBC, a particulate antigen, in rats. Normal rat thymocytes could also be used to study the specific immune reactivity of murine lymphocytes sensitised to SRBC. SRBC immune rat thymocytes functioned as both the migrating cell population and MIF producing cells. This assay permitted study of the interaction between thymocytes and lymphocytes from rats in producing enhanced inhibition of cellular migration. A major advantage of the technique is the possibility of assaying a large number of replicates from abundant normal thymocytes.

Animals↗
PubMed1984

A method using [3H]leucine-labeled granulocytes or macrophages for migration inhibition assay.

The migration inhibitory activity of supernatants of Con A-Sepharose stimulated MNC cultures was tested by measuring the migration of [3H]leucine-labeled granulocytes or macrophages from agarose-containing capillary tube fragments. The migrated cells were harvested with an automated cell harvester on glass fiber filters and counted in a beta counter. Suspension of the target cells in agarose improves the accuracy of the method since migration from packed capillary tube fragments is sometimes not significantly different as between control and assay preparations. The concentration of agarose may inversely influence results, lower concentrations correlating with higher migration inhibition in the presence of assay supernatants. Different migration inhibition results are obtained when allogeneic granulocytes are used in parallel. For this reason a 10 times concentrated supernatant from a Con A-Sepharose-stimulated MNC culture, exhibiting the highest LIF activity at any mitogen concentration, was used as standard considered arbitrarily to contain 100 U. On the parallel regression lines of the dilution curves of the standard and assay preparations, reference with the standard is made at 25% migration inhibition as the comparison point.

Animals↗
PubMed1997

Occupational change, employer change, internal migration, and earnings.

"In this paper I use microdata from the [U.S.] Panel Study of Income Dynamics to measure the financial returns to intercounty and interstate migration for individuals in a temporal framework accounting for gains that accrue over time.... To account for the indirect effects of migration on earnings, explanatory variables are created by interacting migration status with: (1) occupational change, (2) employer change and (3) changes in both occupation and employer. These interaction terms are then included in the earnings functions. Earnings are estimated for three years subsequent to the migration decision to account for the financial returns to migration accruing over time. Results indicate that, when estimating earnings, the use of a simple migration dummy variable will mask the indirect effects of migration on earnings."

Americas↗
PubMed1996

Urban to urban migration: Soviet patterns and post-Soviet implications.

"In spite of extensive literature on migration in the Soviet Union, we know little about household-level decisions. This study specifies and estimates those variables important to understanding the migration decision. Using data from the Soviet Interview Project (SIP), we examine the forces influencing the decision to migrate or not to migrate, and in addition, for those who did migrate, the forces influencing the locational choices made. The results indicate that, while some of the traditional factors influencing migration are important, others are not, suggesting that in the post-Soviet era, differentiating the persistence of Soviet-type forces from emerging market-type forces will be important for an understanding of urban to urban migration."

Behavior↗
PubMed1982

Volatility in the geographical structure of short-run US interstate migration.

"Migration is often thought to be a long-run phenomenon. However, it is shown here by means of labor-force migration estimates derived from the Continuous Work History Sample over the period 1958-1975, that US interstate migration is quite volatile over the short run with respect both to its adjustment to macroeconomic fluctuations and to its geographic structure. A hierarchical clustering routine is utilized to analyse yearly estimates of interstate gross in-migration and out-migration so as to identify the temporal stability and characteristics of the geographical patterns of migration. States enter the national migration linkage tree at different levels for different years, depending upon the level of short-run economic activity." It is also shown that "when national economic conditions worsen, labor-supply adjustments are more localized and the degree of interstate interdependence is less than in times of economic boom."

Americas↗
PubMed1985

Structural-equation models of migration: an example from the Upper Midwest USA.

"To date, most migration models have been specified in terms of a single equation, whereby a set of regional characteristics are used to predict migration rates for various kinds of spatial units. These models are inadequate in at least two respects. First, they omit any causal links between the explanatory variables, thus ignoring indirect effects between these variables and migration. Second, they ignore the possibility of reciprocal causation, or feedback effects, between migration and the explanatory variables...." The author uses data for State Economic Areas to construct a path model and simultaneous-equation model to identify both indirect and feedback effects on migration in the Upper Midwestern United States. "On the basis of the path model, it is suggested that the direct effects of many variables on migration are at least partially offset by the indirect effects, whereas the simultaneous-equation model emphasizes the reciprocal relationship between income and migration."

Americas↗
PubMed1998

Poor people on the move: county-to-county migration and the spatial concentration of poverty.

"Poverty rates in high-poverty and low-poverty rural [U.S.] counties, and, thus, the spatial concentration of poverty, are affected by poverty-specific differences in in-migration and out-migration patterns. These patterns are investigated using 1985-90 county-to-county migration data from the decennial census. Effects on poverty rates of four migration flows (in- and out-migration of poor, in- and out-migration of nonpoor) are quantified, and their impacts on spatial concentration of poverty are assessed. The effect of selected county characteristics on the migration of the poor and nonpoor in nonmetro counties [is] estimated."

Americas↗
PubMed1975

Migration inhibition of human leukocytes mixed with phytohemagglutinin-preincubated mononuclear leukocytes.

An in vitro test able to demonstrate phytohemagglutinin (PHA)-induced migration inhibition of human peripheral blood leukocytes was investigated. The migration inhibition was demonstrated by the agarose migration technique. Purified mononuclear leukocytes which had been incubated for 30 min with PHA, then washed and added to non-separated leukocytes induced migration inhibition of the mixed cell population. Since no PHA was added to the non-separated leukocytes, a direct PHA effect on polymorph migration was avoided. If the PHA-preincubated mononuclear leukocytes were heated at 56 degrees C for 30 min, their ability to cause migration inhibition was abolished. This suggests that the inhibition was caused by migration inhibitory factor (MIF) produced by the PHA-stimulated lymphocytes.

Cell Migration Inhibition↗
PubMed1996

Using moving-industry data to depict U.S. migration patterns.

"Migration analysis is hindered by the lack of up-to-date migration data. This paper examines the feasibility of using information from the American Moving Conference (AMC), the trade organization of the moving industry, to develop timely estimates of gross in- and out-migration and net migration rates at the state level. When adjusted for the spatially varying size of migrant households and the spatially varying market share of the professional moving industry, the number of AMC inbound and outbound shipments provides useful, but slightly imperfect, estimates of migration in 1990 and 1991. Viewed as a time series, adjusted AMC shipment data accurately reveal the major migration stories of the last decade. AMC-based estimates for 1992, 1993, and 1994 provide a picture of state in- and out-migration for years in which official data are not yet available."

Americas↗
PubMed1977

Canine migration inhibitory factor: effect of Corynebacterium parvum administration.

Peripheral blood lymphocytes from dogs sensitized to streptolysin O (SLO) were assayed for migration inhibitory factor (MIF) production by the indirect MIF test, using guinea pig peritoneal exudate cells as the source of macrophages. A specific direct correlation was established between the degree of inhibition of migration and the concentration of SLO-stimulated supernatants from lymphocyte cultures (SLO-S) of untreated normal dogs. Undiluted SLO-S inhibited migration by 66.8%, whereas a dilution of 1:64 elicited a 3% inhibition. In parallel tests, purified protein derivative stimulation of lymphocytes from BCG-vaccinated dogs produced 92.6% inhibition. The effect of Corynebacterium parvum on SLO-specific MIF production was evaluated in three groups of dogs administered a single intramuscular injection of C. parvum at 5 or 50 mg/m(2) or 50 mg/m(2) in suspension with 10 mg of methylprednisolone. Inhibition of migration of macrophages exposed to a 1:4 dilution of SLO-S from dogs inoculated with C. parvum (5 mg/m(2)) was 33% greater (mean inhibition, 75%) than the same SLO-S dilution from uninoculated normal dogs (mean inhibition, 42%) (P < 0.0002). Similarly, lymphocytes from dogs administered 50 mg/m(2) caused an enhancement of migration inhibition, with a mean increase of 26% over controls (P < 0.002), whereas a dose of 50 mg/m(2) with methylprednisolone produced a 16% increase in migration inhibition (P < 0.05). The administration of C. parvum resulted in a three- to fourfold increase in the SLO-S dilution, which would reduce migration by 20% (MIF titer). This increase peaked between days 20 and 30 and lasted over 50 days post-C. parvum inoculation. These findings indicate that C. parvum specifically increases MIF production by canine lymphocytes in a linear correlation with SLO concentration and suggest its use as a stimulant of canine immunity.

Animals↗
PubMed1975

Migration inhibition with various cell fractions in human colorectal cancer.

The unseparated leucocytes, separated mononuclear cells and granulocytes of six control subjects and nine patients with colorectal cancer have been studied by a direct cell migration inhibition technique. A migratory index was calculated from the migration in the presence and absence of a perchloric acid extract of large bowel tumours. In 10% homologous AB serum, no significant migration inhibition occurred with any of the cells from control subjects. Five of the nine cancer patients showed significant inhibition with their unseparated leucocytes, seven of seven with their mononuclear cells, and none of nine with their granulocytes. In 10% autologous serum, some controls exhibited migration inhibition with their unseparated leucocytes and their granulocyte fraction, but not with the mononuclear cell fraction. Migration inhibition was also now apparent in the granulocyte fraction of the cancer patients. It is concluded that, with a soluble tumour antigen preparation, a mononuclear cell population increases the sensitivity of the direct migration inhibition test and that autologous serum may interfere directly with the migration of granulocytes, by an action not dependent upon the release of inhibitory factors from sensitized lymphocytes. This could explain some of the inconsistencies of the assay when using an unseparated leucocyte population.

ABO Blood-Group System↗
PubMed1997

Population growth impacts of zero net international migration.

"In a country such as the United States, the contribution of net international migration to overall population change overshadows the contribution of natural increase.... Some analysts have assumed that if the same number of people leave and enter the country each year, then the effect of net international migration will be zero. This article examines that assumption and shows that it is fallacious. Examining the direct, indirect, total, and negative demographic impacts of zero net international migration through simulations with demographic data, we demonstrate that zero net international migration is not the same and therefore does not have the same demographic results and implications as zero international migration. We conclude that zero net international migration should not be confused with zero international migration."

Americas↗
PubMed1991

[[Regional differences of age-specific migration rates in Japan]].

Changing patterns of age-specific migration rates for the 47 prefectures of Japan are compared for the period 1975-1980 using data from the 1980 census and the migration schedule model developed by Andrei Rogers. "The following four sets of migration rates by five-year age group were handled as observed values: male out-migration, male in-migration, female out-migration, [and] female in-migration." (SUMMARY IN ENG)

Age Factors↗