Alex Bäcker

There is a lot of controversy about the effect of temperature on Coronavirus transmission and Covid-19 infection rates. This is a very important question, for a number of reasons. First, it will determine whether rising temperatures with spring and summer will change the course of the epidemic. Second, it will determine the course of the epidemic in different locations, and thus the recommendations on where people should weather this out, or if it matters. Third, it can have implications for… Show more

There is a lot of controversy about the effect of temperature on Coronavirus transmission and Covid-19 infection rates. This is a very important question, for a number of reasons. First, it will determine whether rising temperatures with spring and summer will change the course of the epidemic. Second, it will determine the course of the epidemic in different locations, and thus the recommendations on where people should weather this out, or if it matters. Third, it can have implications for the temperature at which to keep hospitals, homes and buildings.

Using data on daily infection growth rates across different countries and average temperatures in each, I showed that higher irradiance and higher temperatures correlate with a slower infection growth rate of Covid-19.

Press coverage:
https://www.diepresse.com/5790874/hohe-temperaturen-bremsen-offenbar-sars-cov-2
https://www.krone.at/2124386
https://www.wienerzeitung.at/nachrichten/wissen/mensch/2055731-Waerme-koennte-Entlastung-bringen.html
https://www.salzburg24.at/news/oesterreich/coronavirus-hoehere-temperaturen-koennten-verbreitung-bremsen-85405648
https://boerse-express.com/news/articles/apa-n-a-c-h-r-i-c-h-t-e-n-ue-b-e-r-b-l-i-c-k-197162
https://www.kleinezeitung.at/international/corona/5790882/Hoffnung-auf-Fruehling_Hohe-Temperaturen-sollen-CoronaVirus-bremsen
https://telewizjarepublika.pl/przelomowe-badania-nt-koronawirusa-w-austrii,93408.html
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Video and image datasets can often be described by a small number of parameters, even though each image usually consists of hundreds or thousands of pixels. This observation is often exploited in computer vision and pattern recognition by the application of dimensionality reduction techniques. In particular, there has been recent interest in the application of a class of nonlinear dimensionality reduction algorithms which assume that an image dataset has been sampled from a manifold. From this… Show more

Video and image datasets can often be described by a small number of parameters, even though each image usually consists of hundreds or thousands of pixels. This observation is often exploited in computer vision and pattern recognition by the application of dimensionality reduction techniques. In particular, there has been recent interest in the application of a class of nonlinear dimensionality reduction algorithms which assume that an image dataset has been sampled from a manifold. From this assumption, it follows that estimating the dimension of the manifold is the first step in analyzing an image dataset. Typically, this estimate is obtained either by using a priori knowledge, or by applying one of the various statistical and geometrical methods available. Once an estimate is obtained, it is used as a parameter for the nonlinear dimensionality reduction algorithm. In this paper, we consider reversing this approach. Show less

It is a cliché that the pace of scientific advance is accelerating. All other things equal, this belief would lead to the prediction that, on average, scientific papers build on the findings of ever younger papers. In addition, changes in the distribution of scientific literature may have shifted the network of papers used by the average scientist towards those papers available electronically. We examined the net effect of these forces on a macro scale by looking at the evolution of the age… Show more

It is a cliché that the pace of scientific advance is accelerating. All other things equal, this belief would lead to the prediction that, on average, scientific papers build on the findings of ever younger papers. In addition, changes in the distribution of scientific literature may have shifted the network of papers used by the average scientist towards those papers available electronically. We examined the net effect of these forces on a macro scale by looking at the evolution of the age distribution of references over time. We found that mean reference ages have grown steadily over the last 20 years, and that this growth can be explained by changes in the growth dynamics of science. We show that the presumed exponential growth of scientific output ended before 1960. This growth suffered an abrupt increase in slope ca. 1960, and has followed roughly linear growth since. Both this change and linear growth track growth in academic R&D investment closely. After growth is accounted for, our findings reveal a decrease in the memory of science starting in 1982 that has reversed in the last 10 years. Finally, we show that the aging of 80+-year-old literature seems to have ceased, implying that classics endure indefinitely in the collective memory of science. Show less

Sliding-window cross-correlation is a common method to esimate time-varying correlations between signals (Laurent and Davidowitz, 1994; Laurent et al., 1996; Macleod and Laurent, 1996; Stopfer and Laurent, 1997; Wehr, 1999 (p. 96)). It produces a correlation value betwen two signals (positive or negative) for every (time, lag) pair of values. In principle, the expected value of the correlation for any pair of (time, lag) values must be computed by averaging x (t). y (t+ lag) over many… Show more

Sliding-window cross-correlation is a common method to esimate time-varying correlations between signals (Laurent and Davidowitz, 1994; Laurent et al., 1996; Macleod and Laurent, 1996; Stopfer and Laurent, 1997; Wehr, 1999 (p. 96)). It produces a correlation value betwen two signals (positive or negative) for every (time, lag) pair of values. In principle, the expected value of the correlation for any pair of (time, lag) values must be computed by averaging x (t). y (t+ lag) over many realizations of the stochastic process. This is called an``ensemble average''across realizations of a stochastic process. Lacking a large enough number of realization over which to average, one must resort to other methods. If the correlations are stationary (ie time-invariant), then we may average across time to estimate the expected value. If the correlations are not stationary, we may divide the signals into sliding windows of a size such that the correlations can be considered stationary on the timescale of the window width, and calculate the cross-correlation, as a function of lag, for each window, sliding the window along the signal to obtain correlations for different time values. This is what is called a sliding-window cross-correlogram. Show less

Object recognition requires both specificity, to ensure that stimuli with distinct behavioral relevance are distinguished, and invariance, to ensure that different instances of the same stimulus are recognized as the same under varied conditions (intensity, pitch, position,...). Psychophysical studies show that an odor can be perceived as identical over significant ranges of concentrations. Whether concentration invariance results, at least in part, from low-level neural phenomena rather than… Show more

Object recognition requires both specificity, to ensure that stimuli with distinct behavioral relevance are distinguished, and invariance, to ensure that different instances of the same stimulus are recognized as the same under varied conditions (intensity, pitch, position,...). Psychophysical studies show that an odor can be perceived as identical over significant ranges of concentrations. Whether concentration invariance results, at least in part, from low-level neural phenomena rather than cognitive grouping is so far unknown. I explore, firstly, the contribution of projection neurons (PNs) in the antennal lobe of the locust, the analog of the vertebrate olfactory bulb, to the recognition of odor identity across concentrations; and secondly, what role spike timing, neuronal identity, and synchronization among neuronal assemblies play in the encoding and decoding of odor information by downstream neurons. I show the following: A novel computerized odor delivery system capable of delivering binary mixtures in arbitrary ratios and with arbitrary timecourses selected in real-time. The locust can recognize odors, and shows innate olfactory preferences. PNs solve the task of encoding both odorant concentration and odorant identity, independently of concentration, in three ways. First, by multiplexing information in different response dimensions using a code that involves neuronal identity, spike timing (on a timescale slower than previously believed) and synchronization across a neuronal assembly. Second, via a novel phenomenon of experience-dependent plasticity that contributes to PNs’ invariance to concentration and sensitizes PNs after exposure to an … Show less

First paper to show the function of oscillatory synchronization on the decoding of information by downstream neurons. This seminal paper has been cited over 300 times and continues to be cited to this day more than 20 years after publication.

The corporation is one of the most important inventions in history. Through it, countless teams have aligned their incentives to achieve what would otherwise might well have been impossible. Thanks to the modern corporation, we have cars, search engines, social networks (for good or for bad), airlines, refrigerators and microwave ovens, medicine and plentiful food.

Despite popular perception that it is CEOs that are the top of the corporate ladder, corporations are actually ruled by… Show more

The corporation is one of the most important inventions in history. Through it, countless teams have aligned their incentives to achieve what would otherwise might well have been impossible. Thanks to the modern corporation, we have cars, search engines, social networks (for good or for bad), airlines, refrigerators and microwave ovens, medicine and plentiful food.

Despite popular perception that it is CEOs that are the top of the corporate ladder, corporations are actually ruled by their Boards of Directors. A bad Board of Directors can easily kill off an otherwise great and successful company, even if it has a great CEO. I have seen it happen. And yet there are no qualifications required to become a Director, nor any training usually taken. And while there are thick books on the legal duties of a Director, I know of no easy-to-read book that simply tells Directors how to do a good job. Or at least how to not do a terrible one. That is why I wrote this book.

It is short enough so Directors have no excuse not to read it. I have seen Directors who ignored the wisdom in this book destroy companies that were otherwise healthy, with the subsequent losses in shareholder value, jobs, value for customers and good to society. It is my hope that one day, a book like this will be required reader for anybody aspiring to direct the fates of that wonderful vehicle of progress, the corporation.

The guide for anybody considering joining a board of directors or trying to understand how the governing bodies of corporations work.

Here is an interview Jack Canfield, best-selling author of Chicken Soup for the Soul and The Success Principles did on the book: https://tinyurl.com/jackonblunders

You may learn more in the TEDx talk about it I delivered to a group of McKinsey alumni: https://tinyurl.com/boardblunderstalk Show less

One of the central goals of ecology is to identify mechanisms that maintain biodiversity (Kerr et al., 2002; Chesson, 2000). The stability of biodiversity over millions of years of evolution has been one of the most persistent puzzles of ecology and evolution {Hutchinson, 1961# 723}{Wilson, 1992# 722}. This problem has two separate incarnations that, albeit traditionally treated in different literatures, share fundamental features: species coexistence and genetic polymorphisms. We postulate… Show more

One of the central goals of ecology is to identify mechanisms that maintain biodiversity (Kerr et al., 2002; Chesson, 2000). The stability of biodiversity over millions of years of evolution has been one of the most persistent puzzles of ecology and evolution {Hutchinson, 1961# 723}{Wilson, 1992# 722}. This problem has two separate incarnations that, albeit traditionally treated in different literatures, share fundamental features: species coexistence and genetic polymorphisms. We postulate that these two problems are instances of one general problem and present a model that can explain both puzzles. Show less

A full decade and a half after the first identification of the genes that distinguish glomeruli from each other, how the neurons that express each receptor type manage to find each other to converge onto glomeruli remains a profound mystery. The first processing stage in olfactory systems creates a mapping of olfactory sensory neurons (OSN) to glomeruli. In the adult animal, each glomerulus receives connections from only one OSN species (ie all OSN expressing the same olfactory receptor), and… Show more

A full decade and a half after the first identification of the genes that distinguish glomeruli from each other, how the neurons that express each receptor type manage to find each other to converge onto glomeruli remains a profound mystery. The first processing stage in olfactory systems creates a mapping of olfactory sensory neurons (OSN) to glomeruli. In the adult animal, each glomerulus receives connections from only one OSN species (ie all OSN expressing the same olfactory receptor), and each OSN species connects to at least one glomerulus. The topology of glomerular specialization is conserved across individuals. This elegant mapping sorts out the complex arrangement of OSN on the epithelium into an orderly projection pattern. Yet a full decade and a half after the first identification of the genes that distinguish each OSN and glomeruli type, how the map is established, and maintained throughout life in the face of constant neuronal replacement, remains enigmatic after many years, perhaps the most hotly contested question in olfaction today. Show less

The efficiency of neuronal encoding in sensory and motor systems has been proposed as a first principle governing response properties within the central nervous system. We present a continuation of a theoretical study presented by Zhang and Sejnowski, where the influence of neuronal tuning properties on encoding accuracy is analyzed using information theory. When a finite stimulus space is considered, we show that the encoding accuracy improves with narrow tuning for one- and twodimensional… Show more

The efficiency of neuronal encoding in sensory and motor systems has been proposed as a first principle governing response properties within the central nervous system. We present a continuation of a theoretical study presented by Zhang and Sejnowski, where the influence of neuronal tuning properties on encoding accuracy is analyzed using information theory. When a finite stimulus space is considered, we show that the encoding accuracy improves with narrow tuning for one- and twodimensional stimuli. For three dimensions and higher, there is an optimal tuning width. Show less