An Investigation of Firm Heterogeneity in the Constraints to Development and Growth in Pakistan

This study considers the importance of firm characteristics in explaining the degree of business constraints facing Pakistani firms in the Investment Climate Survey. We quantify how firms with differing characteristics experience particular problems. After controlling for other factors, the largest differences in responses to business constraints occur among firms that vary by manufacturing industry, and among firms operating under different ownership structures or selling in different markets. In some cases, firm size and firm location also play an important role. The age of the firm generally does not lead to significant differences. These results account for the heterogeneity of firms better than others, and may be important for policy-makers to develop more specific approaches to fostering the investment climate.Pakistan, Investment Climate, Business Constraints

Effect of a unilateral hind limb orthotic lift on upper body movement symmetry in the trotting horse

In trotting horses, movement asymmetry is associated with ground reaction force asymmetry. In humans, limb length differences influence contralateral force production. Here we investigate whether horses, in immediate reaction to limb length changes, show movement asymmetry adaptations consistent with reported force differences. Aim of this study was to quantify pelvic and compensatory head and withers movement asymmetry as a function of limb length changes after application of orthotic lifts. In this experimental study movement asymmetry of eleven trotting horses was calculated from vertical displacement of poll, withers, sacrum and left and right tuber coxae with inertial sensors. Horses were assessed in-hand under 5 conditions (all with hind limb boots): without orthotic lifts, and with a 15mm or 30mm orthotic lift applied to the left hind or right hind. A linear mixed model investigated the influence of orthotic lift condition (P<0.05, pairwise posthoc Bonferroni correction). Pelvic movement asymmetry showed increased pelvic downward movement during stance of the shorter limb and increased pelvic upward movement during and after stance of the longer limb (P<0.001) with asymmetry changes of 3-7mm (4-10mm) for 15mm (30mm) lifts. Hip hike (tuber coxae movement asymmetry) was unaffected (P = 0.348). Head and withers movement asymmetry were affected less consistently (2 of 3 respectively 1 of 3 head or withers parameters). The small sample size of the study reduced generalizability, no direct force measurements were conducted and only immediate effects of orthotic lifts were assessed with no re-assessments days or weeks after. Conclusions about mechanical consequences (weight bearing, pushoff) are based on published movement-force associations. Pelvic movement asymmetry with an artificial change in limb length through application of an orthotic lift indicates increased weight support with the shorter limb and increased pushoff with the longer limb. This may be of relevance for the management of horses with different hoof shapes between contralateral limbs, for example some chronically lame horse

An Investigation of Firm Heterogeneity in the Constraints to Development and Growth in Pakistan

This study considers the importance of firm characteristics in explaining the degree of business constraints facing Pakistani firms in the Investment Climate Survey. We quantify how firms with differing characteristics experience particular problems. After controlling for other factors, the largest differences in responses to business constraints occur among firms that vary by manufacturing industry, and among firms operating under different ownership structures or selling in different markets. In some cases, firm size and firm location also play an important role. The age of the firm generally does not lead to significant differences. These results account for the heterogeneity of firms better than others, and may be important for policy-makers to develop more specific approaches to fostering the investment climate

Low Returns and Optimal Retirement Savings

Lifetime financial outcomes relate closely to the sequence of investment returns earned over the lifecycle. Higher return assumptions allow individuals to save at a lower rate, withdraw at a higher rate, retire with a lower wealth accumulation, and enjoy a higher standard of living throughout their lifetimes. Often analysis of this topic is based on the investment performance found in historical market returns. However, at the present bond yields are historically lower and equity prices are quite high, suggesting that individuals will likely experience lower returns in the future. Increases in life expectancy, especially among higher-income workers who must also rely more heavily on their private savings to smooth spending, further increases the cost of funding retirement income today. The implications are higher savings rates, lower withdrawal rates, the need for a larger nest egg at retirement, and a lower lifetime standard of living. We demonstrate this using a basic life cycle framework, and provide a more complex analysis of optimal savings rates that incorporates Social Security, tax rates before and after retirement, actual retirement spending patterns, and differences in expected longevity by income. We find that lower-income workers will need to save about 50 percent more if low rates of return persist in the future, and higher-income workers will need to save nearly twice as much in a low return environment compared to the optimal savings using historical returns

Ab-initio solution of the many-electron Schrödinger equation with deep neural networks

Given access to accurate solutions of the many-electron Schr\"odinger equation, nearly all chemistry could be derived from first principles. Exact wavefunctions of interesting chemical systems are out of reach because they are NP-hard to compute in general, but approximations can be found using polynomially-scaling algorithms. The key challenge for many of these algorithms is the choice of wavefunction approximation, or Ansatz, which must trade off between efficiency and accuracy. Neural networks have shown impressive power as accurate practical function approximators and promise as a compact wavefunction Ansatz for spin systems, but problems in electronic structure require wavefunctions that obey Fermi-Dirac statistics. Here we introduce a novel deep learning architecture, the Fermionic Neural Network, as a powerful wavefunction Ansatz for many-electron systems. The Fermionic Neural Network is able to achieve accuracy beyond other variational quantum Monte Carlo Ans\"atze on a variety of atoms and small molecules. Using no data other than atomic positions and charges, we predict the dissociation curves of the nitrogen molecule and hydrogen chain, two challenging strongly-correlated systems, to significantly higher accuracy than the coupled cluster method, widely considered the most accurate scalable method for quantum chemistry at equilibrium geometry. This demonstrates that deep neural networks can improve the accuracy of variational quantum Monte Carlo to the point where it outperforms other ab-initio quantum chemistry methods, opening the possibility of accurate direct optimisation of wavefunctions for previously intractable molecules and solids

Occurrence of Blarina brevicauda in Arkansas and Notes on the Distribution of Blarina carolinensis and Cryptotis parva

We provide an update on the species and distribution of shrews occurring in Arkansas. Shrews were collected within Arkansas Game and Fish Commission Wildlife Management Areas and along the Buffalo National River. We also searched mammal collections at several institutional museums to provide additional locality records for Cryptotis parva. Specimens of Blarina were identified to species by DNA sequencing of the mitochondrial cytochrome b gene. Previously, Blarina hylophaga was believed to occur in the northwest corner of Arkansas and B. carolinensis throughout the rest of the state. However, our genetic analysis revealed that it is B. brevicauda that occupies the northwestern portion of the state. We also document several new county records for B. carolinensis and C. parva in Arkansas