Aggregate Implications Research Articles

Nonnative structure in a peptide model of the unfolded state of superoxide dismutase 1 (SOD1): Implications for ALS-linked aggregation

Dozens of mutations throughout the sequence of the gene encoding superoxide dismutase 1 (SOD1) have been linked to toxic protein aggregation in the neurodegenerative disease amyotrophic lateral sclerosis (ALS). A parsimonious explanation for numerous genotypes resulting in a common phenotype would be mutation-induced perturbation of the folding free-energy surface that increases the populations of high-energy states prone to aggregation. The absence of intermediates in the folding of monomeric SOD1 suggests that the unfolded ensemble is a potential source of aggregation. To test this hypothesis, here we dissected SOD1 into a set of peptides end-labeled with FRET probes to model the local behavior of the corresponding sequences in the unfolded ensemble. Using time-resolved FRET, we observed that the peptide corresponding to the Loop VII-β8 sequence at the SOD1 C terminus was uniquely sensitive to denaturant. Utilizing a two-dimensional form of maximum entropy modeling, we demonstrate that the sensitivity to denaturant is the surprising result of a two-state-like transition from a compact to an expanded state. Variations of the peptide sequence revealed that the compact state involves a nonnative interaction between the disordered N terminus and the hydrophobic C terminus of the peptide. This nonnative intramolecular structure could serve as a precursor for intermolecular association and result in aggregation associated with ALS. We propose that this precursor would provide a common molecular target for therapeutic intervention in the dozens of ALS-linked SOD1 mutations.

Comparative effects of trehalose and 2-hydroxypropyl-β-cyclodextrin on aggregation of UV-irradiated muscle glycogen phosphorylase b

Chemical chaperones are a class of small molecules which enhance folding and prevent aggregation of proteins. Investigation of their effects on the processes of protein aggregation is of importance for further understanding of implication of protein aggregation in neurodegenerative diseases, as well as for solving biotechnological tasks. The effects of chemical chaperones trehalose and 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) on the kinetics of aggregation of UV-irradiated muscle glycogen phosphorylase b (UV-Phb) at 37 °C have been studied. The process of thermal aggregation of UV-Phb includes a slow stage of structural reorganization of the UV-Phb molecule, nucleation stage and fast attachment of structurally reorganized UV-Phb molecules to nuclei formed during the nucleation stage. It was shown that both trehalose and HP-β-CD increased the duration of the nucleation phase and slowed down the rate of structural reorganization of the UV-Phb molecule. This conclusion has been confirmed by the circular dichroism data. In the absence of chaperones, 82% UV-Phb aggregates, whereas in the presence of HP-β-CD or trehalose the portion of aggregated protein decreases to 70 and 66%, respectively. The data on analytical ultracentrifugation demonstrated that in the presence of these additives the size of protein aggregates decreased. Analysis of the combined effect of trehalose and HP-β-CD on UV-Phb aggregation showed that protein aggregation was independently affected by trehalose and HP-β-CD.

Overreaction in Credit Spreads: The Role of Lenders' Personal Economic Experiences

Do changes in lender optimism lead to excessive fluctuations in credit spreads across the credit cycle? Using data on the real estate properties of loan officers originating large corporate loans, we analyze the role of lenders’ personal economic experiences as a mechanism driving such fluctuations. We provide evidence that lenders overweight their recent locally experienced economic conditions, captured by local housing growth, and this systematically shapes credit spreads for borrowers that own real estate assets and riskier loans. Our analysis suggests that these effects are driven by lenders’ beliefs about real estate values and can have important aggregate implications.

Size-dependent tax enforcement and compliance: Global evidence and aggregate implications

This paper studies how tax enforcement and tax compliance varies with firm size and its macroeconomic consequences. The identification strategy uses the ranking of industries' average firm size in the United States as an instrument for the size ranking of the same industries in developing countries. Data on 125,000 firms in 140 countries shows that tax enforcement and compliance increase with firm size. When quantified in a general equilibrium model, removing size dependent taxation leads to gains in Total Factor Productivity of 1–2%.

Aggregate Implications of Changing Sectoral Trends

Aggregate Implications of Changing Sectoral Trends

Employer Size and Spinout Dynamics

Most new firms are founded by former employees of existing firms – spinouts. This paper documents how employer size shapes the entry and post-entry dynamics of spinouts. Using micro-data from Mexico, I show that employees from small firms are more likely to form spinouts than employees of large firms. In addition, spinouts from large employers start at a larger scale and grow faster than spinouts from small employers. I argue that this results from employees learning from their employers and develop a model of occupational choice and firm dynamics which operationalizes this theory. Using a calibrated version of the model, I analyze the aggregate implications of the link between employer size and spinout dynamics for macroeconomic outcomes both within and across economies. First, I argue that learning efficiency – interpreted as management quality – not only accounts for differences in spinout formation between the U.S. and Mexico, but also explains a sizeable share of the variation in the firm size distribution and output per worker. Second, I show that employee learning has meaningful and long-term implications on the creation of new firms in response to policies that target existing firms. Taken together, this paper establishes a connection between incumbent and entrant firms and shows that it is important for aggregate outcomes.

Product Revenue and Price Setting: Evidence and Aggregate Implications

Using retail scanner data, we find that the probability of price adjustment increases with a product's revenue, and the average absolute size of price adjustment decreases with the product's revenue. Furthermore, the responsiveness of prices to monetary shocks increases with product revenue. These facts are consistent with menu cost models in which the menu cost increases less than one-to-one with revenue, and inconsistent with models in which the menu cost increases one-to-one with revenue. In a calibrated menu cost model, the real effect of monetary policy is smaller in economies in which the price response to monetary policy shocks increases with revenue than in economies where no such relationships exist. Together with cyclical shifts in the revenue distribution, the increase in price responsiveness with revenue introduces a counter-cyclical effect that strengthens the real effect of monetary policy during recessions.

The aggregate implications of changes in the labour force composition

Labour composition by gender, age, and education has undergone dramatic changes over the last half century in the United States. Furthermore, the volatility of total market hours differs systematically between genders, age, and education groups. I develop a large scale business cycle model where these demographic patterns and their transitional dynamics are taken into account and find that demographic change accounts for 30% of the observed changes in aggregate volatility over this period of time. Additionally, these demographic changes are responsible for a significant fraction of the GDP growth observed in the considered period of time.

The New Keynesian cross

The New Keynesian (NK) cross is a graphical and analytical apparatus for heterogeneous-agent (HANK) models expressing key aggregate demand objects—MPC and multipliers—as functions of heterogeneity parameters. It affords analytical insights into monetary, fiscal, and forward guidance multipliers, and replicates the aggregate implications of quantitative HANK. The key parameter—the constrained agents’ income elasticity to aggregate income—depends on fiscal redistribution: when it is larger (smaller) than one, the effects of policies and shocks are amplified (dampened). With uninsurable idiosyncratic uncertainty, this translates intertemporally—through compounding (discounting) in the aggregate Euler equation—into further amplification (dampening) of future shocks.

A “Meta” Analysis of the Fractions Skill Score: The Limiting Case and Implications for Aggregation

AbstractThe fractions skill score (FSS) is arguably one of the most popular spatial verification metrics in use today. The fraction of grid points exceeding a threshold within a forecast and observed field neighborhood are examined to compute a score. By definition a perfect forecast has an FSS of 1, and a “no skill” forecast has a score of 0. It is shown that the denominator defines the score’s characteristics. The FSS is undefined for instances in which both the forecast and the observed field do not exceed a threshold. In the limiting case, the FSS for a perfect null (zero) forecast is also undefined, unless a threshold of 0 is used, in which case it would be 1 (i.e., perfect). Furthermore the FSS is 0 if either the forecast or the observed field does not exceed a threshold. This symmetry means it cannot differentiate between what are traditionally referred to as false alarms or misses. Additional supplementary information is required. The FSS is greater than 0 if and only if there are values exceeding a given threshold in both the forecast and the observed field. The magnitude of an overall score computed over many forecasts is sensitive to the pooling method. Zero scores are nontrivial. Excluding them implies excluding all situations associated with false alarms or misses. Omitting near-zero scores is a more credible decision, but only if it can be proven that these are related to spurious artifacts in the observed field. To avoid ambiguity the components of the FSS should be aggregated separately for computing an overall score for most applications and purposes.

Temporal Aggregation of Seasonally Near‐Integrated Processes

We investigate the implications that temporally aggregating, either by average sampling or systematic (skip) sampling, a seasonal process has on the integration properties of the resulting series at both the zero and seasonal frequencies. Our results extend the existing literature in three ways. First, they demonstrate the implications of temporal aggregation for a general seasonally integrated process with S seasons. Second, rather than only considering the aggregation of seasonal processes with exact unit roots at some or all of the zero and seasonal frequencies, we consider the case where these roots are local‐to‐unity such that the original series is near‐integrated at some or all of the zero and seasonal frequencies. These results show, among other things, that systematic sampling, although not average sampling, can impact on the non‐seasonal unit root properties of the data; for example, even where an exact zero frequency unit root holds in the original data it need not necessarily hold in the systematically sampled data. Moreover, the systematically sampled data could be near‐integrated at the zero frequency even where the original data is not. Third, the implications of aggregation on the deterministic kernel of the series are explored.‐142

Agency Frictions, Managerial Compensation, and Disruptive Innovations

Whether a manager leads the innovation efforts of a firm in line with shareholder preferences is key for firm value and growth. This, in turn, influences aggregate productivity growth and welfare. Data on US public firms reveals that (i) firms with better corporate governance tend to adopt highly incentivized contracts rich in stock options and (ii) such contracts are more likely to lead to disruptive innovations -- patented inventions that are in the upper tail of the distribution in terms of quality and originality. Motivated by these empirical results, we develop and estimate a new dynamic general equilibrium model of firm-level innovation with agency frictions and endogenous determination of executive contracts. The model is used to study the joint dynamics of corporate governance, managerial compensation, and disruptive innovations, as well as the consequent aggregate implications on growth and welfare. Better corporate governance can reduce the influence of the manager in determining the compensation structure. This leads to more incentivized contracts and boosts innovation, with substantial benefits for the shareholders as well as the broader economy through knowledge spillovers. Removing agency frictions leads to contracts richer in stock options, boosting growth by 0.51pp, and welfare by 7.3% in consumption-equivalent terms. These findings are robust to incorporating short-termism. Short-termism itself is also detrimental, the removal of which increases welfare by 1.5%. Alleviating both frictions at the same time leads to amplified gains in growth and welfare.

Lateral water structure connects metal oxide nanoparticle faces

Abstract

Facet-mediated interaction between humic acid and TiO2 nanoparticles: implications for aggregation and stability kinetics in aquatic environments

Humic acid improves TiO2 nanocrystal stability in a facet dependent manner due to the facet-specific SRHA coordination on the TiO2 surface.

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Heterogeneous Real Estate Agents and the Housing Cycle

The real estate market is highly intermediated, with 90% of buyers and sellers hiring an agent to help them transact a house. However, low barriers to entry and fixed commission rates result in a market where inexperienced intermediaries have a large market share, especially following house price booms. Using rich micro-level data on 10.4 million listings, we first show that seller agents’ experience is an important determinant of client outcomes, particularly during real estate busts. Houses listed for sale by inexperienced agents spend more time on the market and have a lower probability of selling. We then study the aggregate implications of the agents’ experience distribution on real estate market liquidity by building a theoretical entry and exit model of real estate agents with aggregate shocks. Several policies that raise the barriers to entry for agents are considered: 1) increased entry costs; 2) lower commission rates; and 3) more informed clients. Across each counterfactual, increasing barriers to entry shift the distribution of agents across experience to the right, improves liquidity, and reduces the amplitude of liquidity cycles in the housing market.

The Aggregate Implications of Regional Business Cycles

Making inferences about aggregate business cycles from regional variation alone is difficult because of economic channels and shocks that differ between regional and aggregate economies. However, we argue that regional business cycles contain valuable information that can help discipline models of aggregate fluctuations. We begin by documenting a strong relationship across U.S. states between local employment and wage growth during the Great Recession. This relationship is much weaker in U.S. aggregates. Then, we present a methodology that combines such regional and aggregate data in order to estimate a medium‐scale New Keynesian DSGE model. We find that aggregate demand shocks were important drivers of aggregate employment during the Great Recession, but the wage stickiness necessary for them to account for the slow employment recovery and the modest fall in aggregate wages is inconsistent with the flexibility of wages we observe across U.S. states. Finally, we show that our methodology yields different conclusions about the causes of aggregate employment and wage dynamics between 2007 and 2014 than either estimating our model with aggregate data alone or performing back‐of‐the‐envelope calculations that directly extrapolate from well‐identified regional elasticities.

The Aggregate Implications of Regional Business Cycles

The Aggregate Implications of Regional Business Cycles

Aggregate implications of occupational inheritance in China and India

Abstract This paper documents occupational inheritance – that is, children’s inheritance of their parents’ occupations – in China, India, and other countries. Among the causes of the prevalence of occupational inheritance, we target two broad categories that impede growth: labor market frictions and barriers to human capital acquisition. Counterfactual experiments based on a tractable occupational choice model suggest that if the impediments mentioned above were reduced to the US levels, labor productivity would grow by 60–75% in China and 107–178% in India. China realized 74–89% of this growth potential from the 1980s to 2009. In addition, this productivity gain is accompanied by a decrease in the correlation of intergenerational incomes.

Cyclical Dynamics of Shopping: Aggregate Implications of Goods and Labor Markets

In this paper, I study the effects of consumers’ shopping effort behavior on aggregate business cycle dynamics. Literature shows that employed individuals search less and pay higher prices for identical goods than unemployed individuals. In addition to this result, using micro-level data, I find that shopping effort of consumers is procyclical, and the procyclicality is more pronounced for the unemployed individuals than employed ones. To explain these empirical facts and study the effects of them on the dynamics of aggregate variables, I build a model of endogenous price hunting in decentralized labor and product markets. I show that an individual buyer exerts less effort in looking for lower prices if the buyer i) has a higher income or ii) is less likely to find lower prices when facing lower price dispersion. Since the return to shopping is procyclical, unemployed buyers exhibit greater procyclicality. The procyclical shopping effort makes firms post relatively greater vacancies in recession than the model with fixed effort as they can post relatively higher prices. I find that while differential shopping behavior of the unemployed and employed amplify the volatilities of aggregate variables, procyclical shopping effort dampens this effect. The model also predicts that price rigidity depends on wage rigidity. I provide empirical evidence for these effects using the time use survey and the scanner data.