ENTERTAINING MALTHUS: BREAD,CIRCUSES, AND ECONOMIC GROWTH

Motivated by the basic adage that man does not live by bread alone, we offer a theory of historical economic growth and population dynamics where human beings need food to survive, but enjoy other things, too. Our model imposes a Malthusian constraint on food, but introduces a second good to the analysis that affects living standards without affecting population growth. We show that technological change does a good job explaining historical consumption patterns and population dynamics, including the Neolithic Revolution, the Industrial Revolution, and the Great Divergence. Our theory stands in contrast to models that assume a single composite good and a Malthusian constraint. These models generate negligible growth prior to the Industrial Revolution. However, recent revisions to historical data show that historical living standards—though obviously much lower than today's—varied over time and space much more than previously thought. These revisions include updates to Maddison's dataset, which served as the basis for many papers taking long‐run stagnation as a point of departure. This new evidence suggests that the assumption of long‐run stagnation is problematic. Our model shows that when we give theoretical accounting of these new observations the Industrial Revolution is much less puzzling. (JEL B10, I31, J1, N1, O30)     

Optimum covariate designs in partially balanced incomplete block (PBIB) design set-ups

The use of covariates in block designs is necessary when the covariates cannot be controlled like the blocking factor in the experiment. In this paper, we consider the situation where there is some flexibility for selection in the values of the covariates. The choice of values of the covariates for a given block design attaining minimum variance for estimation of each of the parameters has attracted attention in recent times. Optimum covariate designs in simple set-ups such as completely randomised design (CRD), randomised block design (RBD) and some series of balanced incomplete block design (BIBD) have already been considered. In this paper, optimum covariate designs have been considered for the more complex set-ups of different partially balanced incomplete block (PBIB) designs, which are popular among practitioners. The optimum covariate designs depend much on the methods of construction of the basic PBIB designs. Different combinatorial arrangements and tools such as orthogonal arrays, Hadamard matrices and different kinds of products of matrices viz. Khatri–Rao product, Kronecker product have been conveniently used to construct optimum covariate designs with as many covariates as possible.     

Optimum designs for parameter estimation in a mixture experiment with two correlated responses

In this paper, we investigate a mixture problem with two responses, which are functions of the mixing proportions, and are correlated with known dispersion matrix. We obtain D- and A-optimal designs for estimating the parameters of the response functions, when none or some of the regression coefficients of the two functions are the same. It is shown that when no prior knowledge about the regression coefficients is available, the D-optimal design is independent of the dispersion matrix, while the A-optimal design depends on it, provided the response functions are of different degree. On the other hand, when some of the regression coefficients are known to be the same for both the functions, the D-optimal design depends on the dispersion matrix when the two response functions are not of the same degree.     

Work and breastfeeding decisions are jointly determined for higher socioeconomic status US mothers

We study postpartum decisions about paid work and breastfeeding using a simultaneous equations model. For our sample of higher socioeconomic status mothers, we find a joint decision process for three sets of decisions modeled: work leave duration and duration of any, as well as of exclusive, breastfeeding, and daily work hours and daily breastfeedings at infant age 3 months. We find that returning to paid work 1 week earlier reduces any breastfeeding duration by about two-thirds of a week while extending breastfeeding by a week delays work participation by about one-third of a week. We find larger elasticities for decisions involving daily work hours and number of breastfeedings at 3 months than for work leave duration and any breastfeeding duration and the smallest elasticities for duration of exclusive breastfeeding and work leave. This marks the first study to find a joint decision-making process for postpartum work and breastfeeding decisions and suggests that, in addition to increased leave impacting breastfeeding behaviors, successful breastfeeding promotion policies can have nontrivial impacts on the US labor market.     

Cell-to-switch level planning in mobile wireless networks for efficient management of radio resources

A major step in effectively managing radio resources in a cellular network is to design an appropriate scheme for assigning cells to a location area (LA), serviced by a switch, and allocate resources for individual switches. However, this assignment is already proven in the literature to be an NP-hard problem [Merchant A, Sengupta B. Assignment of cells to switches in PCS networks. IEEE/ACM Transactions on Networking 3(5) (1995) 521–6] that requires efficient heuristic search techniques for obtaining real-time solutions. This work presents a state-space search technique, which is a variant of best first search heuristic technique. The algorithm called the block depth first search (BDFS), allocates cells to switches during switch level resource planning. Under various simulated performance criteria, we compare the performance of the proposed technique with other similar procedures in the literature. Our results indicate that the BDFS outperforms the meta-heuristic procedures in terms of both efficiency and quality of solutions. Hence, we conclude that our proposed technique can be effectively used for switch level planning leading to an efficient management of scarce radio resource in cellular networks.     

Object Relations Family Therapy: Articulating the Inchoate

In recent years there has been a renewed interest in psychodynamic ideas within the family therapy literature. While some authors have explored the usefulness of psychodynamic concepts in the systemic context (Byng-Hall, 1995; Flaskas, 1993, 1996; Luepnitz, 1988, 1997), others have argued that psychodynamic models of family therapy should be given more credence in systemic work with families (Guttman, 1991). This paper describes Object Relations Family Therapy (ORFT), a psychoanalytic model of family therapy, in plain English in order to minimise the obscurity of some of the existing terminology and to emphasise the utility of more contemporary formulations. ORFT addresses the interface between psychoanalytic and systemic theories. It offers a way of conceptualising complex family dynamics at both the interpersonal and intrapsychic levels. It also integrates an understanding of nonverbal, unstated and often implicit processes in its formulation of problem development. The unique contribution of ORFT is elaborated using a clinical example.     

Combinatorial Equivalence of Fractional Factorial Designs

Two symmetrical fractional factorial designs are said to be combinatorially equivalent if one design can be obtained from another by reordering the runs, relabeling the factors and relabeling the levels of one or more factors. This article presents concepts of ordered distance frequency matrix, distance frequency vector, and reduced distance frequency vector for a design. Necessary conditions for two designs to be combinatorial equivalent based on these concepts are presented. A new algorithm based on the results obtained is proposed to check combinatorial non-equivalence of two factorial designs and several illustrating examples are provided.     

Optimum mixture designs in a restricted region

In a mixture experiment, the response depends on the proportions of the mixing components. Canonical models of different degrees and also other models have been suggested to represent the mean response. Optimum designs for estimation of the parameters of the models have been investigated by different authors. In most cases, the optimum design includes the vertex points of the simplex as support points of the design, which are not mixture combinations in the true non-trivial sense. In this paper, optimum designs have been obtained when the experimental region is an ellipsoidal subspace of the entire factor space which does not cover the vertex points of the simplex.     

Child sexual abuse in Leeds before and after Cleveland

We report a retrospective cohort study in which clinical and outcome features of 237 cases of child sexual abuse diagnosed by Leeds paediatricians after Cleveland in 1989 were compared with previously published characteristics of 337 children diagnosed by the same paediatricians before Cleveland in 1985 and 1986. Clinical and diagnostic features also were analysed in two subgroups of the 1989 cohort, those for whom there was no case conference and those in whom further abuse was detected at follow-up examination. The number of cases diagnosed annually remained high, and source of referrals and age and sex distribution were similar. Most suspected perpetrators were from within the home in both cohorts. Some clinical features of the 1989 cohort suggested more physically severe abuse. In 1989 fewer children were registered as sexually abused, or were taken into care, and fewer suspected perpetrators were convicted. From the 1989 cohort those children for whom there was no case conference tended to be older, to disclose and were abused less severely by someone outside their home as compared to those for whom a case conference was held. The children in whom further abuse was detected tended to be younger, to not disclose. to be more severely abused by a perpetrator within the home and to be taken into care as compared to those in whom further abuse was not detected. One or more case conferences were held for nearly all of the children in whom further abuse was detected. For most of the 1989 children no evidence was found indicating receipt of mental health services from other than the key social worker. Implications of these findings are discussed in terms of professional and public knowledge and attitudes regarding children's and parental rights and family preservation.     

IPPS Sampling Plans Excluding Adjacent Units

The concept of inclusion probability proportional to size sampling plans excluding adjacent units separated by at most a distance of m (≥ 1) units {IPPSEA plans} is introduced. IPPSEA plans ensure that the first-order inclusion probabilities of units are proportional to size measures of the units, while the second-order inclusion probabilities are zero for pairs of adjacent units separated by a distance of m units or less. IPPSEA plans have been obtained by making use of binary, proper, and unequireplicated block designs and linear programing approach. The performance of IPPSEA plans using Horvitz–Thompson estimator of population total has been compared with existing sampling plans such as simple random sampling without replacement (SRSWOR), balanced sampling plans excluding adjacent units {BSA (m) plans}, probability proportional to size with replacement, Hartley and Rao's plan (1962 Hartley , H. O. , Rao , J. N. K. ( 1962 ). Sampling with unequal probabilities and without replacement . Ann. Math. Statist. 33 : 350 – 374 .[Crossref] , [Google Scholar]), Rao et al.'s strategy (1962 Rao , J. N. K. , Hartley , H. O. , Cochran , W. G. ( 1962 ). On a simple procedure of unequal probability sampling without replacement . J. Roy. Statist. Soc. B 24 : 482 – 491 . [Google Scholar]), and Sampford's IPPS plan (1967 Sampford , M. R. ( 1967 ). On sampling without replacement with unequal probabilities of selection . Biometrika 54 ( 3 ): 499 – 513 .[Crossref], [PubMed] , [Google Scholar]) using a real life population. Unbiased estimation of Horvitz–Thompson estimator of population total is not possible in these types of plans because some of the second-order inclusion probabilities are zero. To resolve this problem, one approximate variance estimation technique has been suggested.