The massive increase in the size of deep neural networks (DNNs) is accompanied by a significant increase in energy consumption of their hardware implementations which is critical for their widespread deployment in low-power mobile devices. In our previous work, an abstract hardware-independent model of energy complexity for convolutional neural networks (CNNs) has been proposed and experimentally validated. Based on this model, we provide a theoretical analysis of energy complexity related to the computation of a fully-connected layer when its inputs, outputs, and weights are transferred between two kinds of memories (DRAM and Buffer). First, we establish a general lower bound on this energy complexity. Then, we present two dataflows and calculate their energy costs to achieve the corresponding upper bounds. In the case of a partitioned Buffer, we prove by the weak duality theorem from linear programming that the lower and upper bounds coincide up to an additive constant, and therefore establish the optimal energy complexity. Finally, the asymptotically optimal quadratic energy complexity of fully-connected layers is experimentally validated by estimating their energy consumption on the Simba and Eyeriss hardware.

• Klíčová slova
• Convolutional neural networks, Dataflow, Deep neural networks, Energy complexity, Energy consumption, Fully-connected layer,
• MeSH
• algoritmy MeSH
• deep learning MeSH
• neuronové sítě * MeSH
• počítače MeSH
• programování lineární MeSH
• Publikační typ
• časopisecké články MeSH

The energy efficiency of hardware implementations of convolutional neural networks (CNNs) is critical to their widespread deployment in low-power mobile devices. Recently, a number of methods have been proposed for providing energy-optimal mappings of CNNs onto diverse hardware accelerators. Their estimated energy consumption is related to specific implementation details and hardware parameters, which does not allow for machine-independent exploration of CNN energy measures. In this letter, we introduce a simplified theoretical energy complexity model for CNNs, based on only a two-level memory hierarchy that captures asymptotically all important sources of energy consumption for different CNN hardware implementations. In this model, we derive a simple energy lower bound and calculate the energy complexity of evaluating a CNN layer for two common data flows, providing corresponding upper bounds. According to statistical tests, the theoretical energy upper and lower bounds we present fit asymptotically very well with the real energy consumption of CNN implementations on the Simba and Eyeriss hardware platforms, estimated by the Timeloop/Accelergy program, which validates the proposed energy complexity model for CNNs.

• Publikační typ
• časopisecké články MeSH

Recently a new so-called energy complexity measure has been introduced and studied for feedforward perceptron networks. This measure is inspired by the fact that biological neurons require more energy to transmit a spike than not to fire, and the activity of neurons in the brain is quite sparse, with only about 1% of neurons firing. In this letter, we investigate the energy complexity of recurrent networks, which counts the number of active neurons at any time instant of a computation. We prove that any deterministic finite automaton with m states can be simulated by a neural network of optimal size [Formula: see text] with the time overhead of [Formula: see text] per one input bit, using the energy O(e), for any e such that [Formula: see text] and e=O(s), which shows the time-energy trade-off in recurrent networks. In addition, for the time overhead [Formula: see text] satisfying [Formula: see text], we obtain the lower bound of [Formula: see text] on the energy of such a simulation for some constant c>0 and for infinitely many s.

• MeSH
• akční potenciály fyziologie   MeSH
• algoritmy MeSH
• mozek fyziologie   MeSH
• neuronové sítě * MeSH
• neurony fyziologie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The question remains whether high geopolitical risk and economic policy uncertainty will have a dampening or enhancing effect on pollution factors. In this regard, the study empirically investigates the effects of economic complexity, geopolitical risk, economic policy uncertainty, renewable energy consumption and economic growth on environmental pollution for G-20 countries from 1997 to 2018. The long-term coefficient estimates, derived from the FMOLS estimator, support the inverted U-shaped EKC linkages between economic complexity and ecological footprint, carbon footprint and carbon dioxide emissions. Furthermore, over the long term, geopolitical risks, renewable energy use, and the interaction between economic complexity and policy uncertainty have a positive impact on environmental quality in the G-20 economies. Conversely, economic growth and the interaction between economic complexity and geopolitical risk are negatively associated with environmental quality. Additionally, economic policy uncertainty has a positive effect on ecological footprint carbon footprint and carbon dioxide emissions. Finally, causality results revealed that explanatory variables are the cause of environmental pollution indicators. Hence, in order to advance environmental quality in these nations, precautions must be taken to mitigate the effects of economic policy uncertainty and boost the accessibility of renewable energy sources. Additionally, while not advised as a policy measure, the feasible economic fallout of geopolitical risk should also be considered.

• Klíčová slova
• Ecological footprint, Economic complexity, Economic policy uncertainty, G-20 countries, Geopolitical risk, Renewable energy consumption,
• MeSH
• ekonomický rozvoj * MeSH
• nejistota MeSH
• obnovitelná energie MeSH
• oxid uhličitý * MeSH
• uhlíková stopa MeSH
• znečištění životního prostředí MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• oxid uhličitý * MeSH

As the largest carbon emitter in the world, with its transportation sector contributing the largest shares of its emission, the need for a low-carbon transition economy has become a policy agenda for China because in order to reach carbon neutrality by 2050, lowering the intensity of carbon emissions in the transportation sector will be crucial. In this regard, we used the "bootstrap autoregressive distributed lag model" to explore the impact of clean energy and oil prices on the intensity of carbon emissions in China's transportation sector. The study found that an increase in oil prices decreases the intensity of carbon emissions in the short and long run. Similarly, an increase in the level of renewable energy and economic complexity declines the intensity of carbon emissions in the transportation sector. On the contrary, the research demonstrates that non-renewable energy contributes positively to carbon emission intensity. Therefore, the authorities must promote green technology to neutralize the transportation system's detrimental effects on China's environmental quality. The implications for successfully promoting carbon emission intensity mitigation in the transportation sector are examined in the conclusion.

• Klíčová slova
• Autoregressive distributed lag model, Economic complexity, Oil price, Renewable energy, Transport sector,
• MeSH
• doprava MeSH
• ekonomický rozvoj * MeSH
• obnovitelná energie MeSH
• oxid uhličitý analýza   MeSH
• uhlík * analýza   MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Čína MeSH
• Názvy látek
• oxid uhličitý MeSH
• uhlík * MeSH

Carotenoids are crucial for photosynthesis, playing key roles in light harvesting and photoprotection. In this study, spheroidene and bacteriochlorophyll a (Bchl a) were reconstituted into the chromatophores of the carotenoidless mutant Rhodobacter sphaeroides R26.1, resulting in the preparation of high-quality LH2 complexes. Global and target analyses of transient absorption data revealed that incorporating B800 Bchl a significantly enhances excitation energy transfer (EET) efficiency from carotenoids to Bchl a. EET predominantly occurs from the carotenoid S2 state, with additional pathways from the S1 state observed in native LH2. Unique relaxation dynamics were identified, including the generation of the carotenoid S* state in reconstituted LH2 with both spheroidene and B800 Bchl a and the formation of the carotenoid T1 state in reconstituted LH2. These findings underscore the critical influence of pigment composition and spatial organization on energy transfer mechanisms. They provide valuable insights into the molecular interplay that governs excitation energy transfer in photosynthetic light-harvesting systems.

• Klíčová slova
• B800 bacteriochlorophyll a, carotenoid, light-harvesting, photoprotection, purple photosynthetic bacteria, reconstitution,
• MeSH
• bakteriální proteiny * chemie   metabolismus   MeSH
• bakteriochlorofyl A * chemie   metabolismus   MeSH
• fotosyntéza MeSH
• karotenoidy * metabolismus   chemie   MeSH
• přenos energie * MeSH
• Rhodobacter sphaeroides * metabolismus   chemie   MeSH
• světlosběrné proteinové komplexy * metabolismus   chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• bakteriální proteiny * MeSH
• bakteriochlorofyl A * MeSH
• karotenoidy * MeSH
• spheroidene MeSH Prohlížeč
• světlosběrné proteinové komplexy * MeSH

This study investigates the impact of environmental technological innovation, economic complexity, energy productivity, the use of renewable electricity generation, and environmental taxes on carbon dioxide (CO2) emissions in the G-10 countries for the timeframe from 1995 to 2020. The purpose of the study is to examine the need for a clear plan or strategy to achieve environmental objectives in G-10 countries. In both short-term and long-term projections, the increased use of environment-based technology, economic complexity, and renewable electricity generation has a major positive impact on carbon emission reduction. Moreover, the results demonstrate both unidirectional and bidirectional causality from carbon emissions to renewable energy, electrical generation, and environment-based technologies, respectively. Based on the results, the study proposes a number of concrete policies, such as updating modernized tax systems, increasing tax collection, providing individuals with the means to finance the Sustainable Development Goals through incentive regulations, and making grants from international organizations and the private sector available to finance investments toward the Sustainable Development Goals (SDGs) and carbon neutrality environment targets. This is the study's most significant contribution in order to attain a sustainable and low-carbon future in the G-10 countries, which has policy implications for governments and policymakers.

• Klíčová slova
• Economic complexity, Energy productivity, Environmental taxes, G-10 countries, Renewable electricity, SDGs,
• Publikační typ
• časopisecké články MeSH

The fate of the energy released during the formation of the enzyme-substrate complexes is discussed in connection with energetic aspects of the one-substrate enzyme-catalysed reaction. Assuming a free and rapid intramolecular energy flow in the complex, the high enzyme catalytic activity cannot be explained. It is suggested that a metal ion near the active site can serve as a barrier to the energy flow from the binding sites of the complex into the enzyme molecule. The effective vibrational temperature of the bonded substrate molecule is then higher than the temperature of the reaction system.

• MeSH
• biologické modely MeSH
• energetický metabolismus * MeSH
• enzymy metabolismus   MeSH
• katalýza MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• enzymy MeSH

Photosynthetic organisms had to evolve diverse mechanisms of light-harvesting to supply photosynthetic apparatus with enough energy. Cryptophytes represent one of the groups of photosynthetic organisms combining external and internal antenna systems. They contain one type of immobile phycobiliprotein located at the lumenal side of the thylakoid membrane, together with membrane-bound chlorophyll a/c antenna (CAC). Here we employ femtosecond transient absorption spectroscopy to study energy transfer pathways in the CAC proteins of cryptophyte Rhodomonas salina. The major CAC carotenoid, alloxanthin, is a cryptophyte-specific carotenoid, and it is the only naturally-occurring carotenoid with two triple bonds in its structure. In order to explore the energy transfer pathways within the CAC complex, three excitation wavelengths (505, 590, and 640 nm) were chosen to excite pigments in the CAC antenna. The excitation of Chl c at either 590 or 640 nm proves efficient energy transfer between Chl c and Chl a. The excitation of alloxanthin at 505 nm shows an active pathway from the S2 state with efficiency around 50%, feeding both Chl a and Chl c with approximately 1:1 branching ratio, yet, the S1-route is rather inefficient. The 57 ps energy transfer time to Chl a gives ~25% efficiency of the S1 channel. The low efficiency of the S1 route renders the overall carotenoid-Chl energy transfer efficiency low, pointing to the regulatory role of alloxanthin in the CAC antenna.

• Klíčová slova
• Carotenoids, Cryptophyte, Energy transfer, Light harvesting, Photosynthesis, Ultrafast spectroscopy,
• MeSH
• chlorofyl metabolismus   MeSH
• Cryptophyta fyziologie   MeSH
• fykobiliproteiny metabolismus   MeSH
• přenos energie * MeSH
• xanthofyly metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• alloxanthin MeSH Prohlížeč
• chlorofyl MeSH
• fykobiliproteiny MeSH
• xanthofyly MeSH

The functions of both (bacterio) chlorophylls and carotenoids in light-harvesting complexes have been extensively studied during the past decade, yet, the involvement of BChl a high-energy Soret band in the cascade of light-harvesting processes still remains a relatively unexplored topic. Here, we present transient absorption data recorded after excitation of the Soret band in the LH2 complex from Rhodoblastus acidophilus. Comparison of obtained data to those recorded after excitation of rhodopin glucoside and B800 BChl a suggests that no Soret-to-Car energy transfer pathway is active in LH2 complex. Furthermore, a spectrally rich pattern observed in the spectral region of rhodopin glucoside ground state bleaching (420-550 nm) has been assigned to an electrochromic shift. The results of global fitting analysis demonstrate two more features. A 6 ps component obtained exclusively after excitation of the Soret band has been assigned to the response of rhodopin glucoside to excess energy dissipation in LH2. Another time component, ~ 450 ps, appearing independently of the excitation wavelength was assigned to BChl a-to-Car triplet-triplet transfer. Presented data demonstrate several new features of LH2 complex and its behavior following the excitation of the Soret band.

• Klíčová slova
• Antenna complex, Carotenoids, Electrochromic shift, Energy transfer, Excess energy, LH2,
• MeSH
• bakteriochlorofyly metabolismus   MeSH
• Beijerinckiaceae MeSH
• glukosidy MeSH
• karotenoidy * metabolismus   MeSH
• světlosběrné proteinové komplexy * metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• bakteriochlorofyly MeSH
• glukosidy MeSH
• karotenoidy * MeSH
• rhodopin glucoside MeSH Prohlížeč
• světlosběrné proteinové komplexy * MeSH