Abstract We consider the possibility of indirect detection of dark sector processes by investigating a novel form of interaction between ambient dark matter (DM) and primordial black holes (PBHs). The basic scenario we envisage is that the ambient DM is “dormant”, i.e., it has interactions with the SM, but its potential for an associated SM signal is not realized for various reasons. We argue that the presence of PBHs with active Hawking radiation (independent of any DM considerations) can act as a catalyst in this regard by overcoming the aforementioned bottlenecks. The central point is that PBHs radiate all types of particles, whether in the standard model (SM) or beyond (BSM), which have a mass at or below their Hawking temperature. The emission of such radiation is “democratic” (up to the particle spin), since it is based on a coupling of sorts of gravitational origin. In particular, such shining of (possibly dark sector) particles onto ambient DM can then activate the latter into giving potentially observable SM signals. We illustrate this general mechanism with two specific models. First, we consider asymmetric DM, which is characterized by an absence of ambient anti-DM, and consequently the absence of DM indirect detection signals. In this case, PBHs can “resurrect” such a signal by radiating anti-DM, which then annihilates with ambient DM in order to give SM particles such as photons. In our second example, we consider the PBH emission of dark gauge bosons which can excite ambient DM into a heavier state (which is, again, not ambient otherwise), this heavier state later decays back into DM and photons. Finally, we demonstrate that we can obtain observable signals of these BSM models from asteroid-mass PBHs (Hawking radiating currently with ~ $$ \mathcal{O}\left(\textrm{MeV}\right) $$ O MeV temperatures) at gamma-ray experiments such as AMEGO-X.

• Book : 2025(2)
• Pub. Date : 2025
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Abstract The combination of plastic scintillators with Silicon Photo-Multipliers (SiPMs) is widely used for detecting radiation in high-energy astrophysics, particle physics, neutrino physics, or medical physics. An example of application for this kind of detectors are Compton polarimeters such as POLAR-2 [1,2,3] or LEAP [4,5,6] for which a low-Z material is needed for the Compton effect to be dominant down to as low energy as possible. Such detectors aim to measure low energy Compton depositions in organic scintillators which produce small amounts of optical light because of the low energy deposited and the low scintillation efficiency, and for which optimizing the instrumental optical properties consequently imperative. The light collection efficiency of such a device was studied with a focus on the POLAR-2 Gamma-Ray Burst polarimeter. POLAR-2 consists of a segmented array of 6400 elongated plastic scintillators divided into 100 modules, all read out by SiPMs. The conversion of incoming γ-rays into readable signal goes through the production and collection of optical light, which has been optimized both through measurements and simulations. The optical elements of the POLAR-2 polarimeter prototype module were optically characterized and an optical simulation based on Geant4 was developed to fully model its optical performances. The results from simulations were used to optimize the design and finally to verify its performance. The study resulted in a detector capable of measuring energy depositions of several keV. In addition, an important finding of this work is the impact of the plastic scintillator surface roughness on the light collection. It was found that a plastic scintillator with a higher scintillation efficiency but made of a softer material, hence with a rougher surface, was not necessarily the best option to optimize the light collection. Furthermore, in order to optimize the optical crosstalk between different channels, a production technique for very thin (∼150 μm) and reusable silicone-based optical coupling pads was developed. This method can be adapted to produce either standalone pads or to directly mold a layer on any SiPM to be later coupled to the scintillators. After an introductory discussion describing the need of a large scale GRB polarimeter like POLAR-2, the optical design and characterization of the polarimeter modules that compose its sensitive part are described. The Geant4-based optical simulations of the POLAR-2 modules and the impact of the optical properties of its various elements on the light collection efficiency of the instrument are later presented. The work is finally summarized and an outlook is given on the potential applications of the POLAR-2 optical characterization and simulation work to other experiments employing similar elements.

• Book : 20(02)
• Pub. Date : 2025
• Page : pp.P02010-P02010
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Radioimmunotherapy (RIT) is a novel cancer treatment that combines radiotherapy and immunotherapy to precisely target tumor antigens using monoclonal antibodies conjugated with radioactive isotopes. This approach offers personalized, systemic, and durable treatment, making it effective in cancers resistant to conventional therapies. Advances in artificial intelligence (AI) present opportunities to enhance RIT by improving precision, efficiency, and personalization. AI plays a critical role in patient selection, treatment planning, dosimetry, and response assessment, while also contributing to drug design and tumor classification. This review explores the integration of AI into RIT, emphasizing its potential to optimize the entire treatment process and advance personalized cancer care.

• Book : 15(3)
• Pub. Date : 2025
• Page : pp.397-397
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Abstract Introduction The diagnosis of Growth Hormone Deficiency (GHD) during childhood has been the subject of much controversy over the last few years. Aiming to accurate medical treatment, there is a need for biomarker discovery. Objective To characterize the metabolic profile of GHD children, examine the effect of GH administration on the metabolic signature, and investigate the correlations between metabolites and IGF-1. Methods Nuclear Magnetic Resonance (NMR)-based untargeted and targeted metabolomic approach applied to study the metabolic profiles of children with GHD. Plasma, serum, and urine samples were collected from twenty-two children diagnosed with GHD and forty-eight age matched controls from the Pediatric Endocrinology Unit of the University Hospital of Patras. Experimental data were examined by both multivariate and univariate statistical analysis. Results The results of this pilot study revealed a different metabolic fingerprint of children with GHD in comparison to age-matched healthy individuals. However, the detected alterations in the metabolite patterns before and after GH treatment were subtle and of minor discriminative statistical power. Conclusions This study provides evidence that metabolome plays a pivotal role in GHD, but large-scale multicenter studies are warranted to validate the results.

• Book : 21(1)
• Pub. Date : 2025
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• Pub. Date : 2025
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The International Agency for Research on Cancer (IARC) Monographs Programme plays an important role in cancer prevention by identifying potential carcinogenic hazards. However, the terminology used in IARC’s classifications and Monographs can confuse the public, health professionals, and policymakers. Terms like “carcinogenic to humans” imply causation, although classifications only indicate increased risk under certain conditions. For example, the lifetime incidence of mesothelioma among firefighters is approximately 14 in 10,000, compared to 7 in 10,000 in the general population. Despite doubling the risk, occupational exposure as a firefighter does not cause this type of cancer in 9,986 out of 10,000 firefighters. However, the IARC concludes that “occupational exposure as a firefighter causes mesothelioma” (IARC Working Group on the Identification of Carcinogenic Hazards to Humans. Occupational Exposure as a Firefighter. Lyon: IARC; 2023. pp. 1–730. PMID: 37963216). In addition, the lack of essential information about dosage and context in the IARC carcinogen lists can lead to agents with health benefits under certain conditions (e.g., solar radiation, red meat consumption, approved drugs) being perceived as universally harmful, discouraging beneficial exposures, behaviors, or treatments. Here, I propose renaming the groups of agents classified by the IARC and adding basic labels to specific agents to improve the accuracy and interpretability of the IARC classification lists. These adjustments do not interfere with the IARC’s objective of identifying potential hazards, are easy to implement, and enhance accuracy and clarity, providing stronger support to guide cancer prevention strategies.

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• Pub. Date : 2025
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Abstract Background Chronic periodontitis is a condition impacting approximately 50% of the world’s population. As chronic periodontitis progresses, the bacteria in the oral cavity change resulting in new microbial interactions which in turn influence metabolite production. Chronic periodontitis manifests with inflammation of the periodontal tissues, which is progressively developed due to bacterial infection and prolonged bacterial interaction with the host immune response. The bi-directional relationship between periodontitis and systemic diseases has been reported in many previous studies. Traditional diagnostic methods for chronic periodontitis and systemic diseases such as chronic kidney diseases (CKD) have limitations due to their invasiveness, requiring practised individuals for sample collection, frequent blood collection, and long waiting times for the results. More rapid methods are required to detect such systemic diseases, however, the metabolic profiles of the oral cavity first need to be determined. Aim of review In this review, we explored metabolomics studies that have investigated salivary metabolic profiles associated with chronic periodontitis and systemic illnesses including CKD, oral cancer, Alzheimer’s disease, Parkinsons’s disease, and diabetes to highlight the most recent methodologies that have been applied in this field. Key scientific concepts of the review Of the rapid, high throughput techniques for metabolite profiling, Nuclear magnetic resonance (NMR) spectroscopy was the most applied technique, followed by liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS). Furthermore, Raman spectroscopy was the most used vibrational spectroscopic technique for comparison of the saliva from periodontitis patients to healthy individuals, whilst Fourier Transform Infra-Red Spectroscopy (FT-IR) was not utilised as much in this field. A recommendation for cultivating periodontal bacteria in a synthetic medium designed to replicate the conditions and composition of saliva in the oral environment is suggested to facilitate the identification of their metabolites. This approach is instrumental in assessing the potential of these metabolites as biomarkers for systemic illnesses.

• Book : 21(1)
• Pub. Date : 2025
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Centaurus A (Cen A) is the closest radio galaxy and a prime example of a low-luminosity active galactic nucleus (AGN), exhibiting complex emissions across the electromagnetic spectrum. The nature of its continuum emission, particularly the mechanisms powering it, has been a subject of considerable debate due to the fact that the AGN is deeply buried in dust and therefore not directly observable. This study aims to elucidate the origin of the continuum emission in Cen A and determine the geometrical arrangement of matter in the nuclear region by the mean of optical and near-infrared spectropolarimetry. We obtained spectropolarimetric data of Cen A using the VLT/FORS2, covering the 6100 -- 10300 Å spectral range with an effective resolving power of about 1000. Analysis was conducted on several regions near the obscured AGN, examining total and polarized fluxes, in order to find signatures of the AGN in scattered light. The analysis revealed a region showing strong and narrow emission lines associated with AGN activity. After correction for interstellar polarization in the dust lane (but not for starlight), the intrinsic polarization of the scattered AGN light exhibits a polarization degree of 2 -- 4%, decreasing from optical to near-infrared, associated with a polarization position angle perpendicular to the radio jet axis. We exclude the presence of a hidden broad line in our polarized flux spectrum at ge 99% probability. Narrow emission lines are found to be strongly polarized and orthogonal to the jet position angle. We demonstrate that a beamed synchrotron jet, scattering onto the narrow line region (NLR) best fits all the observational properties reported in this paper and the literature. In this model, the base of the NLR is obscured by a giant (ge 10 pc) circumnuclear region and can only become visible through perpendicular scattering onto the outermost part of the NLR, naturally producing high polarization degrees and polarization angles perpendicular to the radio structure. This study provides strong evidence that Cen A defines a new class of hidden-NLR AGNs in which two other objects naturally find their place (NGC 4258 and 3C 270) and this supports old predictions that beamed synchrotron jets can be observed in reflection. Future surveys should focus on identifying similar hidden-NLR AGNs, especially among misdirected BL Lac AGNs.

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• Pub. Date : 2025
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AbstractThe sub‐Terahertz and Terahertz bands play a critical role in next‐generation wireless communication and sensing technologies, thanks to the large amount of available bandwidth in this spectral regime. While long‐wavelength (microwave to mm‐Wave) and short‐wavelength (near‐infrared to ultraviolet) devices are well‐established and studied, the sub‐THz to THz regime remains relatively underexplored and underutilized. Traditional approaches used in the aforementioned spectral regions are more difficult to replicate in the THz band, leading to the need for the development of novel devices and structures that can manipulate THz radiation effectively. Herein a novel organic, solid‐state electrochemical device is presented, capable of achieving modulation depths of over 90% from ≈500 nm of a conducting polymer that switches conductivity over a large dynamic range upon application of an electronically controllable external bias. The stability of such devices under long‐term, repeated voltage switching, as well as continuous biasing at a single voltage, is also explored. Switching stabilities and long‐term bias stabilities are achieved over two days for both use cases. Additionally, both depletion mode (always “ON”) and accumulation mode (always “OFF”) operation are demonstrated. These results suggest applications of organic electrochemical THz modulators in large area and flexible implementations.

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• Pub. Date : 2025
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• Book : ()
• Pub. Date : 2025
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