•A theory of motor representations is proposed here.•According to this theory, a motor representation is an ensemble of sub-representations.•Each sub-representation has a specific neural underpinning ...and a specific function.•My theory is able to avoid several issues emerging from the literature.
Following neuroscience, and using different labels, several philosophers have addressed the idea of the presence of a single representational mechanism lying in between (visual) perceptual processes and motor processes involved in different functions and useful for shaping suitable action performances: a motor representation (MR). MRs are the naturalized mental antecedents of action. This paper presents a new, non-monolithic view of MRs, according to which, contrarily to the received view, when looking at in between (visual) perceptual processes and motor processes, we find not only a single representational mechanism with different functions, but an ensemble of different sub-representational phenomena, each of which with a different function. This new view is able to avoid several issues emerging from the literature and to address something the literature is silent about, which however turns out to be crucial for a theory of MRs.
This paper addresses the idea of geopolitics of hunger as proposed by a Brazilian geographer, Josué de Castro, whose originality and international impact in the fields of critical geography and ...development studies still merit fuller acknowledgement both within and beyond the discipline of geography. Drawing upon archival research on de Castro's correspondences and scholarly networks and on the editorial history of his key book Geopolitics of Hunger, first I argue that de Castro was a forerunner of the definition of geopolitics in a critical sense and that this nonconformist attitude has been one of the primary reasons for his persistent scholarly neglect. Second, I argue that de Castro's anti-colonial geopolitics, based on subaltern agency, furnishes powerful arguments to present-day critics of 'food security', who challenge the revival of Malthusian concepts, Euro-centric views and neo-colonial recipes in development debates, a clear geopolitical matter for contemporary scholarly and political conversations. Finally, de Castro's international networking and his biography as a political dissident and exile provide some useful practical examples of performing geopolitical discourses outside institutional and statist frameworks.
We present a study on portfolio investments in financial applications. We describe a general modeling and simulation framework and study the impact on the use of different metrics to measure the ...correlation among assets. In particular, besides the traditional Pearson’s correlation, we employ the Detrended Cross-Correlation Analysis (DCCA) and Detrended Partial Cross-Correlation Analysis (DPCCA). Moreover, a novel portfolio allocation scheme is introduced that treats assets as a complex network and uses modularity to detect communities of correlated assets. Weights of the allocation are then distributed among different communities for the sake of diversification. Simulations compare this novel scheme against Critical Line Algorithm (CLA), Inverse Variance Portfolio (IVP), the Hierarchical Risk Parity (HRP). Synthetic times series are generated using the Gaussian model, Geometric Brownian motion, GARCH, ARFIMA and modified ARFIMA models. Results show that the proposed scheme outperforms state of the art approaches in many scenarios. We also validate simulation results via backtesting, whose results confirm the viability of the proposal.
This paper presents a new numerical method for multiscale modeling of composite materials. The new numerical model, called DECM, consists of a DEM (Discrete Element Method) approach of the Cell ...Method (CM) and combines the main features of both the DEM and the CM. In particular, it offers the same degree of detail as the CM, on the microscale, and manages the discrete elements individually such as the DEM-allowing finite displacements and rotations-on the macroscale. Moreover, the DECM is able to activate crack propagation until complete detachment and automatically recognizes new contacts. Unlike other DEM approaches for modeling failure mechanisms in continuous media, the DECM does not require prior knowledge of the failure position. Furthermore, the DECM solves the problems in the space domain directly. Therefore, it does not require any dynamic relaxation techniques to obtain the static solution. For the sake of example, the paper shows the results offered by the DECM for axial and shear loading of a composite two-dimensional domain with periodic round inclusions. The paper also offers some insights into how the inclusions modify the stress field in composite continua.
Using a relativized diquark model Hamiltonian, we calculate the masses of
J
PC
=
0
+
+
ground-state tetraquarks in the following systems:
b
s
b
¯
s
¯
,
b
b
n
¯
n
¯
(
n
=
u
,
d
),
b
b
s
¯
s
¯
,
c
c
c
...¯
c
¯
,
b
b
b
¯
b
¯
,
b
c
b
¯
c
¯
and
b
b
c
¯
c
¯
. We also compute extensive spectra for the fully-heavy quark flavour combinations. Finally, as a test of the diquark model approach, we compute the masses of fully-heavy baryons in the diquark model. Our results may be compared soon to the forthcoming experimental data for fully-heavy three-quark systems.
Microglial cells play essential volume-related actions in the brain that contribute to the maturation and plasticity of neural circuits that ultimately shape behavior. Microglia can thus be expected ...to have similar cell sizes and even distribution both across brain structures and across species with different brain sizes. To test this hypothesis, we determined microglial cell densities (the inverse of cell size) using immunocytochemistry to Iba1 in samples of free cell nuclei prepared with the isotropic fractionator from brain structures of 33 mammalian species belonging to males and females of five different clades. We found that microglial cells constitute ∼7% of non-neuronal cells in different brain structures as well as in the whole brain of all mammalian species examined. Further, they vary little in cell density compared with neuronal cell densities within the cerebral cortex, across brain structures, across species within the same clade, and across mammalian clades. As a consequence, we find that one microglial cell services as few as one and as many as 100 neurons in different brain regions and species, depending on the local neuronal density. We thus conclude that the addition of microglial cells to mammalian brains is governed by mechanisms that constrain the size of these cells and have remained conserved over 200 million years of mammalian evolution. We discuss the probable consequences of such constrained size for brain function in health and disease.
Microglial cells are resident macrophages of the CNS, with key functions in recycling synapses and maintaining the local environment in health and disease. We find that microglial cells occur in similar densities in the brains of different species and in the different structures of each individual brain, which indicates that these cells maintain a similar average size in mammalian evolution, suggesting in turn that the volume monitored by each microglial cell remains constant across mammals. Because the density of neurons is highly variable across the same brain structures and species, our finding implies that microglia-dependent functional recovery may be particularly difficult in those brain structures and species with high neuronal densities and therefore fewer microglial cells per neuron.
This paper discusses the story of a generous popular mobilisation that made possible a peculiar experience of transnational cooperation since the early 1970s. That is, the campaigns in solidarity ...with Mozambican anticolonial resistance that made the small town of Reggio Emilia (Italy) a key place in the processes of Lusophone Africa decolonization, to the point that an oftentold anecdote reports that many Mozambican people sympathetic with anti-colonialist organisation Frelimo believed that Reggio Emilia was the 'capital' of Italy. Indeed, it was mostly from the Emilian town that concrete aid arrived from Italy to Frelimo's clandestine guerrilla bases between Tanzania and Northern Mozambique. Based on the exceptional archives surviving in Reggio, which abundantly document the Reggio-Africa solidarity experience showing that it was not limited to Mozambique, and on original interviews with surviving protagonists, this paper extends and connects for the first time literature on city diplomacy with scholarship on critical, subaltern and liminal geopolitics of decolonization. I especially argue for giving more consideration to a 'radical city diplomacy', which provides examples for constructing geopolitical challenges form below to the state and the territorial models that have dominated mainstream geopolitics hitherto.
This article addresses histories and geographies of the northeast of Brazil in the works of radical Pernambuco geographer Manuel Correia de Andrade and his main intellectual inspirations, such as ...Euclides da Cunha and Josué de Castro. Drawing on current literature on subaltern spaces, critical race studies, and the Modernity-Coloniality-Decoloniality project, I especially consider de Andrade's works that address popular revolts by marginalized and racialized groups in Brazilian history, including the plurisecular saga of black slaves' quilombos and their role in the abolition of slavery, as well as the formation of Brazilian territories. My main argument is that the marginalized groups analyzed in these works, similar to more studied cases such as Haiti's revolutionaries, provided examples of subaltern agency and resistance by taking their freedom by themselves, through direct action, without waiting for legitimation from their European counterparts. Subaltern spaces, intended as spaces of resistance, are key to understanding these movements. The fact that members of the radical circuits of Brazilian and Pernambucan geography in the second half of the twentieth century showed awareness of what today is called the coloniality of power and colonial difference accounts for the effectiveness of studying linguistically and culturally different geographical traditions to decolonize (Western and English-speaking) academia. Key Words: alternative geographical traditions, decolonial turn, northeast of Brazil, quilombos, subaltern space.
PDF
