140 research outputs found
Communication-Efficient Federated Learning for LEO Satellite Networks Integrated with HAPs Using Hybrid NOMA-OFDM
Space AI has become increasingly important and sometimes even necessary for
government, businesses, and society. An active research topic under this
mission is integrating federated learning (FL) with satellite communications
(SatCom) so that numerous low Earth orbit (LEO) satellites can collaboratively
train a machine learning model. However, the special communication environment
of SatCom leads to a very slow FL training process up to days and weeks. This
paper proposes NomaFedHAP, a novel FL-SatCom approach tailored to LEO
satellites, that (1) utilizes high-altitude platforms (HAPs) as distributed
parameter servers (PS) to enhance satellite visibility, and (2) introduces
non-orthogonal multiple access (NOMA) into LEO to enable fast and
bandwidth-efficient model transmissions. In addition, NomaFedHAP includes (3) a
new communication topology that exploits HAPs to bridge satellites among
different orbits to mitigate the Doppler shift, and (4) a new FL model
aggregation scheme that optimally balances models between different orbits and
shells. Moreover, we (5) derive a closed-form expression of the outage
probability for satellites in near and far shells, as well as for the entire
system. Our extensive simulations have validated the mathematical analysis and
demonstrated the superior performance of NomaFedHAP in achieving fast and
efficient FL model convergence with high accuracy as compared to the
state-of-the-art
One-Shot Federated Learning For LEO Constellations That Reduces Convergence Time From Days To 90 Minutes
A Low Earth orbit (LEO) satellite constellation consists of a large number of small satellites traveling in space with high mobility and collecting vast amounts of mobility data such as cloud movement for weather forecast, large herds of animals migrating across geo-regions, spreading of forest fires, and aircraft tracking. Machine learning can be utilized to analyze these mobility data to address global challenges, and Federated Learning (FL) is a promising approach because it eliminates the need for transmitting raw data and hence is both bandwidth and privacy friendly. However, FL requires many communication rounds between clients (satellites) and the parameter server (PS), leading to substantial delays of up to several days in LEO constellations. In this paper, we propose a novel one-shot FL approach for LEO satellites, called LEOShot, that needs only a single communication round to complete the entire learning process. LEOShot comprises three processes: (i) synthetic data generation, (ii) knowledge distillation, and (iii) virtual model retraining. We evaluate and benchmark LEOShot against the state of the art and the results show that it drastically expedites FL convergence by more than an order of magnitude. Also surprisingly, despite the one-shot nature, its model accuracy is on par with or even outperforms regular iterative FL schemes by a large margin
Optimizing Federated Learning In LEO Satellite Constellations Via Intra-Plane Model Propagation And Sink Satellite Scheduling
The advances in satellite technology developments have recently seen a large number of small satellites being launched into space on Low Earth orbit (LEO) to collect massive data such as Earth observational imagery. The traditional way which downloads such data to a ground station (GS) to train a machine learning (ML) model is not desirable due to the bandwidth limitation and intermittent connectivity between LEO satellites and the GS. Satellite edge computing (SEC), on the other hand, allows each satellite to train an ML model onboard and uploads only the model to the GS which appears to be a promising concept. This paper proposes FedLEO, a novel federated learning (FL) framework that realizes the concept of SEC and overcomes the limitation (slow convergence) of existing FL-based solutions. FedLEO (1) augments the conventional FL\u27s star topology with \u27horizontal\u27 intra-plane communication pathways in which model propagation among satellites takes place; (2) optimally schedules communication between \u27sink\u27 satellites and the GS by exploiting the predictability of satellite orbiting patterns. We evaluate FedLEO extensively and benchmark it with the state of the art. Our results show that FedLEO drastically expedites FL convergence, without sacrificing-in fact it considerably increases-the model accuracy
S-Methylcysteine (SMC) Ameliorates Intestinal, Hepatic, and Splenic Damage Induced by Cryptosporidium parvum Infection Via Targeting Inflammatory Modulators and Oxidative Stress in Swiss Albino Mice
Cryptosporidiosis has been proposed to be one of the major causes of diarrhoeal disease in
humans worldwide that possesses zoonotic concern. Thereby, this study investigated the potential
effects of s-Methylcysteine (SMC) on the parasite in vivo followed by the measurement of cytokines,
oxidative stress parameters, and an investigation of the major histopathological changes. Sixty male
Swiss albino mice weighing 20–25 g were allocated equally into five groups and orally administered
saline only (control), SMC only (SMC50) (50 mg/kg b.w.), and 104 Cryptosporidium parvum oocysts
per mouse via an esophageal tube (C + ve untreated). The fourth and fifth groups (C + SMC25,
C + SMC50) administrated 104 C. parvum oocysts combined with SMC25 (low dose) and 50 (high
dose) mg/kg b.w., respectively. At days 7 and 14 post-infection (PI), the feces was collected from
each group in order to count C. parvum oocysts. After two weeks of treatment, the animals were
euthanized and the serum was collected for biochemical analysis. Next, the intestinal, spleen, and
liver sections were dissected for histopathological examination. The results revealed lower oocyst
numbers in the C + SMC25 and C + SMC50 groups compared to the infected untreated group.
Moreover, higher doses of SMC treatment significantly reduced the enteritis induced by C. parvum in a
dose-dependent manner. The hepatic lesions were also mitigated as demonstrated in C + SMC25 and C + SMC50 groups unlike the infected group via lowering the serum alanine aminotransferase (ALT),
aspartate aminotransferase (AST), and alkaline phosphatase (ALP) enzymes and increasing albumin
and globulin serum levels. SMC administration also reduced cytokines production (SAP, TNF-α, IL-6,
and IFN-γ) mediated by Cryptosporidium infection in contrast to the infected untreated group. There
were marked lymphoid depletion and amyloidosis observed in the infected untreated group, while
the treated groups showed obvious increase in the lymphoid elements. Moreover, the scoring of
intestinal parasites, hepatic, and splenic lesions in the SMC-treated groups exhibited significantly
lower pathological lesions in different organs in a dose-dependent manner, compared to the infected
untreated group. Our results also revealed a significant change in the malondialdehyde content with
an elevation of glutathione and superoxide dismutase in the intestines collected from C + SMC25
and C + SMC50 mice relative to the untreated group. Taken together, our results indicated that
SMC could be a promising effective compound for treating and declining C. parvum infestation via
restoring structural alterations in different tissues, enhancing antioxidant enzymes, and suppressing
the cytokines liberation
A Brain-Computer Interface Augmented Reality Framework with Auto-Adaptive SSVEP Recognition
Brain-Computer Interface (BCI) initially gained attention for developing
applications that aid physically impaired individuals. Recently, the idea of
integrating BCI with Augmented Reality (AR) emerged, which uses BCI not only to
enhance the quality of life for individuals with disabilities but also to
develop mainstream applications for healthy users. One commonly used BCI signal
pattern is the Steady-state Visually-evoked Potential (SSVEP), which captures
the brain's response to flickering visual stimuli. SSVEP-based BCI-AR
applications enable users to express their needs/wants by simply looking at
corresponding command options. However, individuals are different in brain
signals and thus require per-subject SSVEP recognition. Moreover, muscle
movements and eye blinks interfere with brain signals, and thus subjects are
required to remain still during BCI experiments, which limits AR engagement. In
this paper, we (1) propose a simple adaptive ensemble classification system
that handles the inter-subject variability, (2) present a simple BCI-AR
framework that supports the development of a wide range of SSVEP-based BCI-AR
applications, and (3) evaluate the performance of our ensemble algorithm in an
SSVEP-based BCI-AR application with head rotations which has demonstrated
robustness to the movement interference. Our testing on multiple subjects
achieved a mean accuracy of 80\% on a PC and 77\% using the HoloLens AR
headset, both of which surpass previous studies that incorporate individual
classifiers and head movements. In addition, our visual stimulation time is 5
seconds which is relatively short. The statistically significant results show
that our ensemble classification approach outperforms individual classifiers in
SSVEP-based BCIs
Secure and Efficient Federated Learning in LEO Constellations using Decentralized Key Generation and On-Orbit Model Aggregation
Satellite technologies have advanced drastically in recent years, leading to
a heated interest in launching small satellites into low Earth orbit (LEOs) to
collect massive data such as satellite imagery. Downloading these data to a
ground station (GS) to perform centralized learning to build an AI model is not
practical due to the limited and expensive bandwidth. Federated learning (FL)
offers a potential solution but will incur a very large convergence delay due
to the highly sporadic and irregular connectivity between LEO satellites and
GS. In addition, there are significant security and privacy risks where
eavesdroppers or curious servers/satellites may infer raw data from satellites'
model parameters transmitted over insecure communication channels. To address
these issues, this paper proposes FedSecure, a secure FL approach designed for
LEO constellations, which consists of two novel components: (1) decentralized
key generation that protects satellite data privacy using a functional
encryption scheme, and (2) on-orbit model forwarding and aggregation that
generates a partial global model per orbit to minimize the idle waiting time
for invisible satellites to enter the visible zone of the GS. Our analysis and
results show that FedSecure preserves the privacy of each satellite's data
against eavesdroppers, a curious server, or curious satellites. It is
lightweight with significantly lower communication and computation overheads
than other privacy-preserving FL aggregation approaches. It also reduces
convergence delay drastically from days to only a few hours, yet achieving high
accuracy of up to 85.35% using realistic satellite images
Feline Leishmaniosis in Northwestern Italy: Current Status and Zoonotic Implications
Leishmaniasis remains one of the major neglected tropical diseases. The epidemiological
profile of the disease comprises a wide range of hosts, including dogs and cats. Despite several
studies about feline Leishmaniosis, the role of cats in disease epidemiology and its clinical impact
is still debated. The present study raises awareness about the impact of leishmaniasis in cats from
an endemic region in of Northwestern Italy (Liguria). A total number of 250 serum and 282 blood
samples were collected from cats, then assessed for Leishmania infantum (L. infantum) serologically
using western blot (WB) and molecularly using polymerase chain reaction (PCR). We also tested the
association of Leishmania infection with some infectious agents like haemotropic Mycoplasma, Feline
immunodeficiency virus (FIV) and Feline leukemia virus (FeLV) together with the hematobiochemical
status of the examined animals. Interestingly, all tested animals were asymptomatic and out of
250 examined serum samples, 33 (13.20%) samples (confidence interval (CI) 95% 9.56–17.96%) were
positive at WB for L. infantum, whereas of the 282 blood samples, 80 (28.36%) returned a positive PCR
(CI 95% 23.43–33.89%). Furthermore, there was a statistical association between PCR positivity for
L. infantum and some hematological parameters besides FIV infection as well as a direct significant
correlation between Mycoplasma infection and WB positivity. Taken together, the present findings
report high prevalence of L. infantum among cats, which reinforces the significance of such positive
asymptomatic animals and confirms the very low humoral response in this species. In addition,
the laboratory values provide evidence that infection by the parasite is linked to alteration of some
hematological parameters and is correlated to some infectious agents. These data are of interest and
suggest future research for accurate diagnosis of such zoonosis
Diagnosis of leishmaniasis
This work was supported by EK Elmahallawy, who has a PhD scholarship (number 736) from Erasmus Mundus Scholarship Programme (ELEMENT Action 1 First call).Leishmaniasis is a clinically heterogeneous syndrome caused by intracellular protozoan parasites of the genus Leishmania. The clinical
spectrum of leishmaniasis encompasses subclinical ( not apparent), localized (skin lesion), and disseminated (cutaneous, mucocutaneous, and
visceral) infection. This spectrum of manifestations depends on the immune status of the host, on the parasite, and on immunoinflammatory
responses. Visceral leishmaniasis causes high morbidity and mortality in the developing world. Reliable laboratory methods become
mandatory for accurate diagnosis, especially in immunocompromised patients such as those infected with HIV. In this article, we review the
current state of the diagnostic tools for leishmaniasis, especially the serological test.Erasmus Mundus Scholarship Programme (ELEMENT Action 1 First call)
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Melatonin Enhances the Mitochondrial Functionality of Brown Adipose Tissue in Obese—Diabetic Rats
Developing novel drugs/targets remains a major effort toward controlling obesity-related
type 2 diabetes (diabesity). Melatonin controls obesity and improves glucose homeostasis in rodents,
mainly via the thermogenic effects of increasing the amount of brown adipose tissue (BAT) and
increases in mitochondrial mass, amount of UCP1 protein, and thermogenic capacity. Importantly,
mitochondria are widely known as a therapeutic target of melatonin; however, direct evidence of
melatonin on the function of mitochondria from BAT and the mechanistic pathways underlying these
effects remains lacking. This study investigated the effects of melatonin on mitochondrial functions
in BAT of Zücker diabetic fatty (ZDF) rats, which are considered a model of obesity-related type 2
diabetes mellitus (T2DM). At five weeks of age, Zücker lean (ZL) and ZDF rats were subdivided
into two groups, consisting of control and treated with oral melatonin for six weeks. Mitochondria
were isolated from BAT of animals from both groups, using subcellular fractionation techniques,
followed by measurement of several mitochondrial parameters, including respiratory control ratio
(RCR), phosphorylation coefficient (ADP/O ratio), ATP production, level of mitochondrial nitrites,
superoxide dismutase activity, and alteration in the mitochondrial permeability transition pore
(mPTP). Interestingly, melatonin increased RCR in mitochondria from brown fat of both ZL and
ZDF rats through the reduction of the proton leak component of respiration (state 4). In addition,
melatonin improved the ADP/O ratio in obese rats and augmented ATP production in lean rats.
Further, melatonin reduced mitochondrial nitrosative and oxidative status by decreasing nitrite
levels and increasing superoxide dismutase activity in both groups, as well as inhibited mPTP
in mitochondria isolated from brown fat. Taken together, the present data revealed that chronic
oral administration of melatonin improved mitochondrial respiration in brown adipocytes, while
decreasing oxidative and nitrosative stress and susceptibility of adipocytes to apoptosis in ZDF rats,
suggesting a beneficial use in the treatment of diabesity. Further research regarding the molecular
mechanisms underlying the effects of melatonin on diabesity is warranted.SAF2016-79794-R from the Ministerio de Ciencia e
Innovación (Spain)European Regional Development Fund (ERDF
Mitotic Arrest-Deficient 2 Like 2 (MAD2L2) Interacts with Escherichia coli Effector Protein EspF
Enteropathogenic (EPEC) and Enterohemorrhagic (EHEC) Escherichia coli are considered emerging zoonotic pathogens of worldwide distribution. The pathogenicity of the bacteria is conferred by multiple virulence determinants, including the locus of enterocyte effacement (LEE) pathogenicity island, which encodes a type III secretion system (T3SS) and effector proteins, including the multifunctional secreted effector protein (EspF). EspF sequences differ between EPEC and EHEC serotypes in terms of the number and residues of SH3-binding polyproline-rich repeats and N-terminal localization sequence. The aim of this study was to discover additional cellular interactions of EspF that may play important roles in E. coli colonization using the Yeast two-hybrid screening system (Y2H). Y2H screening identified the anaphase-promoting complex inhibitor Mitotic Arrest-Deficient 2 Like 2 (MAD2L2) as a host protein that interacts with EspF. Using LUMIER assays, MAD2L2 was shown to interact with EspF variants from EHEC O157:H7 and O26:H11 as well as EPEC O127:H6. MAD2L2 is targeted by the non-homologous Shigella effector protein invasion plasmid antigen B (IpaB) to halt the cell cycle and limit epithelial cell turnover. Therefore, we postulate that interactions between EspF and MAD2L2 serve a similar function in promoting EPEC and EHEC colonization, since cellular turnover is a key method for bacteria removal from the epithelium. Future work should investigate the biological importance of this interaction that could promote the colonization of EPEC and EHEC E. coli in the host
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