We characterize the dynamic universality classes of a relaxational dynamicsunder equilibrium conditions at the continuous transitions of three-dimensional(3D) spin systems with a ${\mathbb Z}_2$-gauge symmetry. In particular, weconsider the pure lattice ${\mathbb Z}_2$-gauge model and the lattice ${\mathbbZ}_2$-gauge XY model, which present various types of transitions: topologicaltransitions without a local order parameter and transitions characterized byboth gauge-invariant and non-gauge-invariant XY order parameters. We consider astandard relaxational (locally reversible) Metropolis dynamics and determinethe dynamic critical exponent $z$ that characterizes the critical slowing downof the dynamics as the continuous transition is approached. At the topological${\mathbb Z}_2$-gauge transitions we find $z=2.55(6)$. Therefore, the dynamicsis significantly slower than in Ising systems -- $z\approx 2.02$ for the 3DIsing universality class -- although 3D ${\mathbb Z}_2$-gauge systems and Isingsystems have the same static critical behavior because of duality. As for thenontopological transitions in the 3D ${\mathbb Z}_2$-gauge XY model, we findthat their critical dynamics belong to the same dynamic universality class asthe relaxational dynamics in ungauged XY systems, independently of thegauge-invariant or nongauge-invariant nature of the order parameter at thetransition.
We consider the three-dimensional (3D) lattice SU($N_c$) gauge Higgs theorieswith multicomponent ($N_f>1$) degenerate scalar fields and U($N_f$) globalsymmetry, focusing on systems with $N_c=2$, to identify critical behaviors thatcan be effectively described by the corresponding 3D SU($N_c$) gauge Higgsfield theory. The field-theoretical analysis of the RG flow allows one toidentify a stable charged fixed point for large values of $N_f$, that wouldcontrol transitions characterized by the global symmetry-breaking pattern ${\rmU}(N_f)\rightarrow \mathrm{SU}(2)\otimes \mathrm{U}(N_f-2)$. Continuoustransitions with the same symmetry-breaking pattern are observed in the SU(2)lattice gauge model for $N_f \ge 30$. Here we present a detailed finite-sizescaling analysis of the Monte Carlo data for several large values of $N_f$. Theresults are in substantial agreement with the field-theoretical predictionsobtained in the large-$N_f$ limit. This provides evidence that the SU($N_c$)gauge Higgs field theories provide the correct effective description of the 3Dlarge-$N_f$ continuous transitions between the disordered and the Higgs phase,where the flavor symmetry breaks to $\mathrm{SU}(2)\otimes \mathrm{U}(N_f-2)$.Therefore, at least for large enough $N_f$, the 3D SU($N_c$) gauge Higgs fieldtheories with multicomponent scalar fields can be nonperturbatively defined bythe continuum limit of lattice discretizatized models with the same local andglobal symmetries.
This review investigates cyber-attacks and countermeasures of the perception layer in electromedical devices used in decentralized healthcare contexts. Emphasis is placed on sensing and actuation functionalities performed outside hospital environments, where physical exposure and heterogeneous communication protocols increase threat complexity. A systematic search was performed across Scopus, Web of Science, IEEE Xplore, and PubMed using a structured query covering cybersecurity threats and countermeasures in perception-layer medical devices. Only peer-reviewed English articles were included. Screening and eligibility assessment followed PRISMA guidelines and Kitchenham’s methodology, excluding studies unrelated to perception-layer cybersecurity or lacking countermeasure discussion. A structured framework was developed to classify devices, attack types, and defensive strategies. Twenty-one studies were included, revealing a research focus on wearable devices and monitoring functionalities, while portable and implantable systems with actuation capabilities remain underexplored. Most documented attacks involve replay, DoS, eavesdropping, and Man-in-the-Middle attacks, whereas advanced threats like side-channel attacks are rarely addressed. Defensive strategies mainly rely on authentication schemes and transmission-level cryptography, while recovery capabilities are inadequately addressed. Research on perception-layer cybersecurity in electromedical devices is still fragmented, with uneven protection of critical security properties. Future work should expand to implantable and actuation-enabled devices, develop multi-layer defenses addressing all security objectives, and introduce resilience mechanisms to support robust cybersecurity in decentralized healthcare environments.
We analyzed the dynamic response to the light of organic field-effect transistors in bottom-gate/top-contact configuration. We fabricated Al/Al2O3/SAM/DNTT/Au phototransistors by evaporating thin film layers through shadow masks on flexible PEN (polyethylene naphthalate) substrates. The structure is composed of Al layer as the gate electrode, and Au used both for Source and Drain electrodes. DNTT (Dinaphtho2,3-b:2’,3’-fthieno3,2-bthiophene) is the active organic semiconductor layer and Al2O3 is the dielectric material, chosen for the high value of the dielectric constant. SAM (self-assembled monolayer) was used to improve adhesion and interface properties between Al2O3 and DNTT. The transistors, sensitive to blue light, were biased at low-voltage bias (Vgs and Vds from 0 to 3.5 V). Devices showed low Igs leakage currents, of the order of 5×10-10 A, and a clear electro-optical response to the light. The maximum responsivity value was about 0.21 A/W in the static regime, while the lowest irradiance producing a measurable response in dynamic regime was 13 μ W/cm2. Fast time components of the rise time of the light response for the analyzed phototransistors, of the order of few hundreds of ms, turned out to be among the fastest reported in literature for Al/AlOx/DNTT/Au organic phototransistor. These preliminary results are encouraging for developing organic phototransistors for visible light communication.