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10 authors named L.A. Times Critics at Large, will contribute to Books section

The Times has assembled a panel of distinguished and diverse writers who will regularly contribute to the Books section. 




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Kings pay tribute to Kobe Bryant at Staples Center: 'It's going to sting for a while'

The Kings let the Tampa Bay Lightning come back for a 4-2 win on the night Kobe Bryant is remembered.




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Unmasking the artist behind John Gibson's tribute to Kobe Bryant

When Kobe Bryant died in a helicopter crash, Ducks goalie John Gibson wanted to honor the Lakers legend with his mask. He knew just who to contact.




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Angels to distribute $1.2 million to stadium workers per agreement with MLB

The Angels will pay at least $1.2 million to workers who would have staffed games at Angel Stadium, including those contracted by third parties.




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Philipp Plein's fashion tribute to Kobe Bryant garners mixed reaction

Retailing for $2,070 and $3,150, respectively, the Philipp Plein tank top and hoodie are being sold to support the Mamba & Mambacita Sports Foundation, which was started by Lakers legend Kobe Bryant.




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L.A.'s theater community pays tribute to its ultimate fan, Kerry English

Kerry English was a beloved "professional audience member," a fan who saw up to five shows a week and provided the support theaters so critically need.




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Alicia Keys was 'freaking out' before her Grammys tribute to Kobe Bryant

Appearing on "The Ellen DeGeneres Show," Grammys host Alicia Keys detailed the backstage frenzy that preceded her poignant tribute to Kobe Bryant.




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Priyanka Chopra, Riz Ahmed pay tribute to Irrfan Khan, 'a thoughtful man'

Hollywood and Bollywood stars honor Indian actor Irrfan Khan ('Slumdog Millionaire,' 'Life of Pi'), who died Wednesday at 53.




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Peter Whittingham tributes: Football world pays respects to former Cardiff star



Peter Whittingham's death has taken the world of football by shock.




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Even during lockdown, Britain paid tribute to WW2 heroes, says LEO McKINSTRY



THE commemoration was heartfelt, the nostalgia moving, the gratitude profound.




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Queen VE Day speech: Queen shares 'vivid' WW2 memories and 'pride' in tribute to UK heroes



THE QUEEN's powerful VE Day speech touched the hearts of Britons around the country as she reflected on her personal memories of World War 2 and sent her "warmest good wishes" to everyone celebrating in lockdown.




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Even during lockdown, Britain paid tribute to WW2 heroes, says LEO McKINSTRY



THE commemoration was heartfelt, the nostalgia moving, the gratitude profound.




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Even during lockdown, Britain paid tribute to WW2 heroes, says LEO McKINSTRY



THE commemoration was heartfelt, the nostalgia moving, the gratitude profound.




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F-35 jets fly over Utah as tribute to workers on frontline of COVID-19 fight

F-35 jets fly over Utah as tribute to workers on frontline of COVID-19 fight

       




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Blue Angels may fly over Indy in tribute to frontline workers battling coronavirus

Officials would direct the Navy's Blue Angels and Air Force's Thunderbirds to fly over Indianapolis, Washington, New York and others

       




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Indiana will distribute new federal unemployment benefits. It will just take time.

Indiana will issue unemployment benefits to workers who do not typically qualify. But distributing new federal stimulus money will take time.

       




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Doughnuts from reopened Long's Bakery inspire tasty hip-hop tribute

Indianapolis rapper Tevin Studdard celebrates the return of Long's Bakery with "Long's Bakery Music Video," a tribute to glazed yeast doughnuts.

       




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Distributed Node.js

Node.js is used by many companies for building performant backend services without sacrificing developer efficiency. In this hands-on guide, author Thomas Hunter II proves that Node.js is just as capable as traditional enterprise platforms for building services that are observable, scalable, and resilient. Intermediate to advanced Node.js developers will find themselves integrating application code with a breadth of tooling from each layer of a modern service stack.




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Pro-515 of the dynamin-like GTPase MxB contributes to HIV-1 inhibition by regulating MxB oligomerization and binding to HIV-1 capsid [Microbiology]

Interferon-regulated myxovirus resistance protein B (MxB) is an interferon-induced GTPase belonging to the dynamin superfamily. It inhibits infection with a wide range of different viruses, including HIV-1, by impairing viral DNA entry into the nucleus. Unlike the related antiviral GTPase MxA, MxB possesses an N-terminal region that contains a nuclear localization signal and is crucial for inhibiting HIV-1. Because MxB previously has been shown to reside in both the nuclear envelope and the cytoplasm, here we used bioinformatics and biochemical approaches to identify a nuclear export signal (NES) responsible for MxB's cytoplasmic location. Using the online computational tool LocNES (Locating Nuclear Export Signals or NESs), we identified five putative NES candidates in MxB and investigated whether their deletion caused nuclear localization of MxB. Our results revealed that none of the five deletion variants relocates to the nucleus, suggesting that these five predicted NES sequences do not confer NES activity. Interestingly, deletion of one sequence, encompassing amino acids 505–527, abrogated the anti-HIV-1 activity of MxB. Further mutation experiments disclosed that amino acids 515–519, and Pro-515 in particular, regulate MxB oligomerization and its binding to HIV-1 capsid, thereby playing an important role in MxB-mediated restriction of HIV-1 infection. In summary, our results indicate that none of the five predicted NES sequences in MxB appears to be required for its nuclear export. Our findings also reveal several residues in MxB, including Pro-515, critical for its oligomerization and anti-HIV-1 function.




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Pro-515 of the dynamin-like GTPase MxB contributes to HIV-1 inhibition by regulating MxB oligomerization and binding to HIV-1 capsid [Microbiology]

Interferon-regulated myxovirus resistance protein B (MxB) is an interferon-induced GTPase belonging to the dynamin superfamily. It inhibits infection with a wide range of different viruses, including HIV-1, by impairing viral DNA entry into the nucleus. Unlike the related antiviral GTPase MxA, MxB possesses an N-terminal region that contains a nuclear localization signal and is crucial for inhibiting HIV-1. Because MxB previously has been shown to reside in both the nuclear envelope and the cytoplasm, here we used bioinformatics and biochemical approaches to identify a nuclear export signal (NES) responsible for MxB's cytoplasmic location. Using the online computational tool LocNES (Locating Nuclear Export Signals or NESs), we identified five putative NES candidates in MxB and investigated whether their deletion caused nuclear localization of MxB. Our results revealed that none of the five deletion variants relocates to the nucleus, suggesting that these five predicted NES sequences do not confer NES activity. Interestingly, deletion of one sequence, encompassing amino acids 505–527, abrogated the anti-HIV-1 activity of MxB. Further mutation experiments disclosed that amino acids 515–519, and Pro-515 in particular, regulate MxB oligomerization and its binding to HIV-1 capsid, thereby playing an important role in MxB-mediated restriction of HIV-1 infection. In summary, our results indicate that none of the five predicted NES sequences in MxB appears to be required for its nuclear export. Our findings also reveal several residues in MxB, including Pro-515, critical for its oligomerization and anti-HIV-1 function.




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The heme-regulatory motifs of heme oxygenase-2 contribute to the transfer of heme to the catalytic site for degradation [Protein Structure and Folding]

Heme-regulatory motifs (HRMs) are present in many proteins that are involved in diverse biological functions. The C-terminal tail region of human heme oxygenase-2 (HO2) contains two HRMs whose cysteine residues form a disulfide bond; when reduced, these cysteines are available to bind Fe3+-heme. Heme binding to the HRMs occurs independently of the HO2 catalytic active site in the core of the protein, where heme binds with high affinity and is degraded to biliverdin. Here, we describe the reversible, protein-mediated transfer of heme between the HRMs and the HO2 core. Using hydrogen-deuterium exchange (HDX)-MS to monitor the dynamics of HO2 with and without Fe3+-heme bound to the HRMs and to the core, we detected conformational changes in the catalytic core only in one state of the catalytic cycle—when Fe3+-heme is bound to the HRMs and the core is in the apo state. These conformational changes were consistent with transfer of heme between binding sites. Indeed, we observed that HRM-bound Fe3+-heme is transferred to the apo-core either upon independent expression of the core and of a construct spanning the HRM-containing tail or after a single turnover of heme at the core. Moreover, we observed transfer of heme from the core to the HRMs and equilibration of heme between the core and HRMs. We therefore propose an Fe3+-heme transfer model in which HRM-bound heme is readily transferred to the catalytic site for degradation to facilitate turnover but can also equilibrate between the sites to maintain heme homeostasis.




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CBD Communiqué: G-77 Ministers Pay Special Tribute to CBD Secretariat's Leading Role in South-South Cooperation.




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CBD News: The Secretariat of the Convention on Biological Diversity (CBD) has welcomed the Warsaw Framework for REDD+ for its potential to contribute both to climate change mitigation and biodiversity conservation.




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CBD News: Montreal/Paris, 26 May 2016 - More and more people are aware of biodiversity. If credible information and reputable brands are available, consumers are ready to purchase biodiversity-friendly products and contribute to the conservation and susta




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CBD News: The booming illegal trade in wildlife products contributes to the continued erosion of Earth's precious biodiversity. The unsustainable rate of loss of animals robs us of our national heritage, and cultural ties, and can drive whole species




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CBD Notification SCBD/SSSF/AS/ML/GD/88414 (2019-114): Tracking Economic Instruments and Finance for Biodiversity: Invitation to contribute data on positive incentives relevant to Aichi Biodiversity Target 3 to the OECD PINE database




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CBD Notification SCBD/IMS/JMF/NVW/86292 (2019-117): Follow-up invitation to participate in and/or contribute to the piloting and further development of a methodology for the voluntary peer review of national biodiversity strategies and action plans




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Gov’t to distribute reusable masks

The Government will distribute free reusable face masks to all Hong Kong citizens, the Innovation & Technology Bureau announced today.

 

The CuMask, made with six layers and special ergonomic features, was developed by the Hong Kong Research Institute of Textiles & Apparel.

 

Two of its layers contain copper which is capable of immobilising bacteria, common viruses and other harmful substances.

 

The mask complies with the American Society for Testing & Materials F2100 Level 1 Standard in terms of particle and bacterial filtration efficiency, resistance to penetration by synthetic blood, and flammability and pressure resistance.

 

It is also reusable for up to 60 washes.

 

The bureau said, except for babies and infants, all holders of valid Hong Kong identity cards are eligible to obtain a mask.

 

Citizens can register online from 7am tomorrow till June 6. Each registration can cater for a maximum of six persons.

 

Upon successful registration, the mask will be delivered to the door by Hongkong Post within two weeks.

 

Primary and kindergarten students will each be given two masks, which will be delivered directly to children's schools. Parents do not have to register.

 

The Government has also arranged to deliver over 140,000 of the masks to residential homes and social welfare institutions for their distribution to those including elderly and the homeless.

 

Click here for registration details.




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The heme-regulatory motifs of heme oxygenase-2 contribute to the transfer of heme to the catalytic site for degradation [Protein Structure and Folding]

Heme-regulatory motifs (HRMs) are present in many proteins that are involved in diverse biological functions. The C-terminal tail region of human heme oxygenase-2 (HO2) contains two HRMs whose cysteine residues form a disulfide bond; when reduced, these cysteines are available to bind Fe3+-heme. Heme binding to the HRMs occurs independently of the HO2 catalytic active site in the core of the protein, where heme binds with high affinity and is degraded to biliverdin. Here, we describe the reversible, protein-mediated transfer of heme between the HRMs and the HO2 core. Using hydrogen-deuterium exchange (HDX)-MS to monitor the dynamics of HO2 with and without Fe3+-heme bound to the HRMs and to the core, we detected conformational changes in the catalytic core only in one state of the catalytic cycle—when Fe3+-heme is bound to the HRMs and the core is in the apo state. These conformational changes were consistent with transfer of heme between binding sites. Indeed, we observed that HRM-bound Fe3+-heme is transferred to the apo-core either upon independent expression of the core and of a construct spanning the HRM-containing tail or after a single turnover of heme at the core. Moreover, we observed transfer of heme from the core to the HRMs and equilibration of heme between the core and HRMs. We therefore propose an Fe3+-heme transfer model in which HRM-bound heme is readily transferred to the catalytic site for degradation to facilitate turnover but can also equilibrate between the sites to maintain heme homeostasis.




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Timing of immune response to COVID-19 may contribute to disease severity

(Keck School of Medicine of USC) A new USC study suggests that temporarily suppressing the body's immune system during the early stages of COVID-19 could help a patient avoid severe symptoms. That's because the research shows that an interaction between the body's two main lines of defense may be causing the immune system to go into overdrive in some patients.




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Effects of recommender systems in e-commerce vary by product attributes and review ratings

(Carnegie Mellon University) A new study sought to determine how the impact of recommender systems (also called recommenders) is affected by factors such as product type, attributes, and other sources of information about products on retailers' websites. The study found that recommenders increased the number of consumer views of product pages as well as the number of products consumers consider, but that the increase was moderated by product attributes and review ratings.




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JCF distribute PSOJ COVID-19 food packages

Members of the Jamaica Constabulary Force on Thursday, distributed more than 300 food packages to individuals and families impacted by COVID-19 in St. James, under the Private Sector Organisation of Jamaica (PSOJ)-led COVID-19 Response Fund...




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Phosphatidylinositol Metabolism, Phospholipases, Lipidomics, and Cancer:In Memoriam of Michael J. O. Wakelam (1955-2020) [Tribute]




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In Memoriam: Lina M. Obeid (1957-2019) [Tribute]




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The heme-regulatory motifs of heme oxygenase-2 contribute to the transfer of heme to the catalytic site for degradation [Protein Structure and Folding]

Heme-regulatory motifs (HRMs) are present in many proteins that are involved in diverse biological functions. The C-terminal tail region of human heme oxygenase-2 (HO2) contains two HRMs whose cysteine residues form a disulfide bond; when reduced, these cysteines are available to bind Fe3+-heme. Heme binding to the HRMs occurs independently of the HO2 catalytic active site in the core of the protein, where heme binds with high affinity and is degraded to biliverdin. Here, we describe the reversible, protein-mediated transfer of heme between the HRMs and the HO2 core. Using hydrogen-deuterium exchange (HDX)-MS to monitor the dynamics of HO2 with and without Fe3+-heme bound to the HRMs and to the core, we detected conformational changes in the catalytic core only in one state of the catalytic cycle—when Fe3+-heme is bound to the HRMs and the core is in the apo state. These conformational changes were consistent with transfer of heme between binding sites. Indeed, we observed that HRM-bound Fe3+-heme is transferred to the apo-core either upon independent expression of the core and of a construct spanning the HRM-containing tail or after a single turnover of heme at the core. Moreover, we observed transfer of heme from the core to the HRMs and equilibration of heme between the core and HRMs. We therefore propose an Fe3+-heme transfer model in which HRM-bound heme is readily transferred to the catalytic site for degradation to facilitate turnover but can also equilibrate between the sites to maintain heme homeostasis.




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Actor Boy Awards pays tribute to those we lost - Event goes online Saturday

Choreographer and designer Barry Moncrieffe; actress Lois Kelly Miller; New York-based broadcaster Gil Bailey; and actor and teacher Carl Samuels will all be remembered with a special tribute at Saturday’s staging of the annual Actor Boy Awards....




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Tribute to Prof Fred Hickling

THE EDITOR, Madam: Words cannot describe my feeling of loss on hearing that prominent psychiatrist Professor Fred Hickling has died. Professor Hickling was one of Jamaica’s treasures through his work in the field of community mental health. His...




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How the New Indonesia-EU FLEGT Licence Can Contribute to the Sustainable Development Agenda

15 November 2016

Alison Hoare

Senior Research Fellow, Energy, Environment and Resources Programme
The FLEGT timber licence marks a breakthrough in the battle against illegal logging and has the potential to help towards achieving the SDGs in the forest sector and beyond.

2016-11-15-Indonesia-logging.jpg

Collected logs along a river in West Kalimantan province, Indonesia. Photo by Getty Images.

Today Indonesia begins issuing the first ever FLEGT licenses for timber exports bound for the EU market. A major step in the battle against illegal logging and trade in illegal timber, these licenses are issued under a national system to verify the legality of all timber and timber products. A commitment to licensing its timber exports to Europe was made in the country’s Voluntary Partnership Agreement (VPA) with the EU, although the licensing system applies to all exports and to the domestic market. The scale of this achievement can not be underestimated given the size of the country and of its forest sector – there are hundreds of thousands of forest enterprises ranging from large-scale concession holders and processing industries, to smallholders and micro-scale loggers, saw-millers and manufacturers.

It is also remarkable given the state of Indonesia’s forest sector at the turn of the century. Looking back to 2000, rule of law was all but absent and corruption was rife - with the allocation of concessions and timber industries closely tied with the country’s ruling elite. Widespread logging contributed to the high rates of deforestation seen at the turn of the century, which stood at over one per cent per year.

In 2016, the forest sector is vastly different – there are much higher levels of accountability and legal compliance, the result of the considerable effort and resources that have been put into enforcement and anti-corruption efforts. The sector is also much more open, reflected both in the significant improvements in the availability of forest data and legislation as well as the increased space that has been made available to civil society to participate both in policy processes and in monitoring of the sector.

These improvements are the result in large part of the reform processes that have been enabled and supported by the VPA process, for which negotiations began in 2007. However, the process is far from complete and the issuance of FLEGT licences is best viewed as a marking point in an ongoing trajectory towards establishing a legal and sustainable sector.

If we take 2000 as the starting point of this trajectory, with FLEGT licensing as the midway point, this brings us to just beyond 2030, the target date for the UN’s global agenda for sustainable development of which the Sustainable Development Goals (SDG) are an integral part. The SDGs provide a broader framework for considering what further progress is needed in the coming years both to improve legality and to ensure that the forest sector makes a positive contribution towards achieving widespread sustainable development in Indonesia.

There are a number of factors that risk the achievement of these aims. Key challenges that remain in the country’s forest sector include the high levels of informality in the small-scale sector, corruption, limited transparency and pressure on forests from other sectors (as highlighted in the report 'Illegal Logging and Related Trade. The Response in Indonesia').

As noted, there are hundreds of thousands of forest enterprises in the country, many of which – particularly small-scale businesses – operate informally. Further concerted efforts are needed to ensure that these enterprises are not excluded from the formal market, but are able to contribute to a thriving economy – for example, through continued support for certification, as well as much greater investment in the provision of extension services and further reforms to establish a policy framework that facilitates the growth of small businesses (see 'Improving Legality Among Small-Scale Forest Enterprises'). This will make an important contribution to the achievement of SDG 8, to enable ‘decent work and economic growth’, this including the target [8.3] to encourage the growth of small enterprises.

Both corruption and limited transparency also need to be addressed if widespread legality and sustainability are to be achieved in the forest sector. Transparency has improved greatly in the forest sector, with significant improvements to the availability of information and the establishment of independent monitoring by civil society. However, further progress is needed to improve the accessibility of information, not least to ensure that NGOs are able to fulfil this monitoring role. In relation to corruption, the anti-corruption agency has made good progress, but it remains under threat and needs to be strengthened. Improving governance is a priority under the SDGs, Goal 16 (peace, justice and strong institutions) including targets to reduce corruption, develop transparent institutions and ensure public access to information.  

The progress made in these areas also needs to be replicated outside the forest sector. A major threat to Indonesia’s forests comes from conversion to other land-uses, in particular agricultural plantations. Effective land-use planning, including transparent and participatory decision-making, is needed if the sustainable management and efficient use of natural resources is to be achieved and deforestation slowed – as set out under SDG 12 (responsible consumption and production) and SDG 15 (life on land).

An important means to drive progress is to ensure close monitoring of progress as well as the evaluation of the measures being adopted. A framework for monitoring the impact of FLEGT licences, as well as the related measures being implemented under the VPA, is under development. This will need to link up to national efforts to monitor progress towards the SDGs – both to contribute towards the monitoring of these goals and to facilitate communication of the progress and lessons being learnt in the forest sector.

To comment on this article, please contact Chatham House Feedback




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A Tribute to My Colleagues and All Those Working in Mental Health

During a time when the world is focused on the current COVID-19 pandemic, a physical health crisis, and all those treating the physical symptoms of this pandemic, we must not...




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[ Religion & Spirituality ] Open Question : How come there are different writers attributed to the Gospel of Mark.... why would Mark need different people to write his Gospel.?




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A tribute to Katherine

I have never watched Hidden Figures. Was that a bad way to start off an article concerning the late Katherine Johnson, the NASA legend whose persistence, precision, and proclivity for mathematics sent America to space in the 1960s? Maybe it was. … Continue reading




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Fortitude with her attributes. Engraving by J. Frey, 1725, after D. Zampieri, il Domenichino.

[Rome], [1725]




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Justice with her attributes. Engraving by J. Frey, 1725, after D. Zampieri, il Domenichino.

[Rome], [1725]




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The winged head of a demon (?). Drawing attributed to J. Vanderbank.




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Role of doctors for youth and smoking in international youth year / [distributed by Cleanair]

Calcutta, India : Cleanair, Campaign for Smoke-free Environment, [198-?]




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Distributed Feature Screening via Componentwise Debiasing

Feature screening is a powerful tool in processing high-dimensional data. When the sample size N and the number of features p are both large, the implementation of classic screening methods can be numerically challenging. In this paper, we propose a distributed screening framework for big data setup. In the spirit of 'divide-and-conquer', the proposed framework expresses a correlation measure as a function of several component parameters, each of which can be distributively estimated using a natural U-statistic from data segments. With the component estimates aggregated, we obtain a final correlation estimate that can be readily used for screening features. This framework enables distributed storage and parallel computing and thus is computationally attractive. Due to the unbiased distributive estimation of the component parameters, the final aggregated estimate achieves a high accuracy that is insensitive to the number of data segments m. Under mild conditions, we show that the aggregated correlation estimator is as efficient as the centralized estimator in terms of the probability convergence bound and the mean squared error rate; the corresponding screening procedure enjoys sure screening property for a wide range of correlation measures. The promising performances of the new method are supported by extensive numerical examples.




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Graph-Dependent Implicit Regularisation for Distributed Stochastic Subgradient Descent

We propose graph-dependent implicit regularisation strategies for synchronised distributed stochastic subgradient descent (Distributed SGD) for convex problems in multi-agent learning. Under the standard assumptions of convexity, Lipschitz continuity, and smoothness, we establish statistical learning rates that retain, up to logarithmic terms, single-machine serial statistical guarantees through implicit regularisation (step size tuning and early stopping) with appropriate dependence on the graph topology. Our approach avoids the need for explicit regularisation in decentralised learning problems, such as adding constraints to the empirical risk minimisation rule. Particularly for distributed methods, the use of implicit regularisation allows the algorithm to remain simple, without projections or dual methods. To prove our results, we establish graph-independent generalisation bounds for Distributed SGD that match the single-machine serial SGD setting (using algorithmic stability), and we establish graph-dependent optimisation bounds that are of independent interest. We present numerical experiments to show that the qualitative nature of the upper bounds we derive can be representative of real behaviours.




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WONDER: Weighted One-shot Distributed Ridge Regression in High Dimensions

In many areas, practitioners need to analyze large data sets that challenge conventional single-machine computing. To scale up data analysis, distributed and parallel computing approaches are increasingly needed. Here we study a fundamental and highly important problem in this area: How to do ridge regression in a distributed computing environment? Ridge regression is an extremely popular method for supervised learning, and has several optimality properties, thus it is important to study. We study one-shot methods that construct weighted combinations of ridge regression estimators computed on each machine. By analyzing the mean squared error in a high-dimensional random-effects model where each predictor has a small effect, we discover several new phenomena. Infinite-worker limit: The distributed estimator works well for very large numbers of machines, a phenomenon we call 'infinite-worker limit'. Optimal weights: The optimal weights for combining local estimators sum to more than unity, due to the downward bias of ridge. Thus, all averaging methods are suboptimal. We also propose a new Weighted ONe-shot DistributEd Ridge regression algorithm (WONDER). We test WONDER in simulation studies and using the Million Song Dataset as an example. There it can save at least 100x in computation time, while nearly preserving test accuracy.




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GADMM: Fast and Communication Efficient Framework for Distributed Machine Learning

When the data is distributed across multiple servers, lowering the communication cost between the servers (or workers) while solving the distributed learning problem is an important problem and is the focus of this paper. In particular, we propose a fast, and communication-efficient decentralized framework to solve the distributed machine learning (DML) problem. The proposed algorithm, Group Alternating Direction Method of Multipliers (GADMM) is based on the Alternating Direction Method of Multipliers (ADMM) framework. The key novelty in GADMM is that it solves the problem in a decentralized topology where at most half of the workers are competing for the limited communication resources at any given time. Moreover, each worker exchanges the locally trained model only with two neighboring workers, thereby training a global model with a lower amount of communication overhead in each exchange. We prove that GADMM converges to the optimal solution for convex loss functions, and numerically show that it converges faster and more communication-efficient than the state-of-the-art communication-efficient algorithms such as the Lazily Aggregated Gradient (LAG) and dual averaging, in linear and logistic regression tasks on synthetic and real datasets. Furthermore, we propose Dynamic GADMM (D-GADMM), a variant of GADMM, and prove its convergence under the time-varying network topology of the workers.




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Distributed estimation of principal eigenspaces

Jianqing Fan, Dong Wang, Kaizheng Wang, Ziwei Zhu.

Source: The Annals of Statistics, Volume 47, Number 6, 3009--3031.

Abstract:
Principal component analysis (PCA) is fundamental to statistical machine learning. It extracts latent principal factors that contribute to the most variation of the data. When data are stored across multiple machines, however, communication cost can prohibit the computation of PCA in a central location and distributed algorithms for PCA are thus needed. This paper proposes and studies a distributed PCA algorithm: each node machine computes the top $K$ eigenvectors and transmits them to the central server; the central server then aggregates the information from all the node machines and conducts a PCA based on the aggregated information. We investigate the bias and variance for the resulting distributed estimator of the top $K$ eigenvectors. In particular, we show that for distributions with symmetric innovation, the empirical top eigenspaces are unbiased, and hence the distributed PCA is “unbiased.” We derive the rate of convergence for distributed PCA estimators, which depends explicitly on the effective rank of covariance, eigengap, and the number of machines. We show that when the number of machines is not unreasonably large, the distributed PCA performs as well as the whole sample PCA, even without full access of whole data. The theoretical results are verified by an extensive simulation study. We also extend our analysis to the heterogeneous case where the population covariance matrices are different across local machines but share similar top eigenstructures.