112 research outputs found
Bucks for Buckets (B4B): Active Defenses Against Stealing Encoders
Machine Learning as a Service (MLaaS) APIs provide ready-to-use and
high-utility encoders that generate vector representations for given inputs.
Since these encoders are very costly to train, they become lucrative targets
for model stealing attacks during which an adversary leverages query access to
the API to replicate the encoder locally at a fraction of the original training
costs. We propose Bucks for Buckets (B4B), the first active defense that
prevents stealing while the attack is happening without degrading
representation quality for legitimate API users. Our defense relies on the
observation that the representations returned to adversaries who try to steal
the encoder's functionality cover a significantly larger fraction of the
embedding space than representations of legitimate users who utilize the
encoder to solve a particular downstream task.vB4B leverages this to adaptively
adjust the utility of the returned representations according to a user's
coverage of the embedding space. To prevent adaptive adversaries from eluding
our defense by simply creating multiple user accounts (sybils), B4B also
individually transforms each user's representations. This prevents the
adversary from directly aggregating representations over multiple accounts to
create their stolen encoder copy. Our active defense opens a new path towards
securely sharing and democratizing encoders over public APIs.Comment: Accepted at NeurIPS202
Towards More Realistic Membership Inference Attacks on Large Diffusion Models
Generative diffusion models, including Stable Diffusion and Midjourney, can
generate visually appealing, diverse, and high-resolution images for various
applications. These models are trained on billions of internet-sourced images,
raising significant concerns about the potential unauthorized use of
copyright-protected images. In this paper, we examine whether it is possible to
determine if a specific image was used in the training set, a problem known in
the cybersecurity community and referred to as a membership inference attack.
Our focus is on Stable Diffusion, and we address the challenge of designing a
fair evaluation framework to answer this membership question. We propose a
methodology to establish a fair evaluation setup and apply it to Stable
Diffusion, enabling potential extensions to other generative models. Utilizing
this evaluation setup, we execute membership attacks (both known and newly
introduced). Our research reveals that previously proposed evaluation setups do
not provide a full understanding of the effectiveness of membership inference
attacks. We conclude that the membership inference attack remains a significant
challenge for large diffusion models (often deployed as black-box systems),
indicating that related privacy and copyright issues will persist in the
foreseeable future
Off-pump versus on-pump coronary artery surgery in octogenarians (from the KROK Registry)
BackgroundAccording to the medical literature, both on-pump and off-pump coronary artery surgery is safe and effective in octogenarians.ObjectivesThe aim of our study was to examine the epidemiology, in-hospital outcomes and long-term follow-up results in octogenarians undergoing off-pump and on-pump coronary artery surgery utilizing nationwide registry data.MethodsAll octogenarians (≥ 80 years) enrolled in the Polish National Registry of Cardiac Surgical Procedures (KROK Registry), who underwent isolated coronary surgery between January 2006 and September 2017 were identified. Preoperative data, perioperative complications, hospital mortality and long-term mortality were analyzed. Unadjusted and propensity-matched comparisons were performed between octogenarians undergoing off-pump and on-pump coronary artery bypass surgery.ResultsOctogenarians accounted for 4.1% of the total population undergoing coronary artery surgery in Poland during the analyzed period (n = 152,631) and this percentage is increasing. Among 6,006 analyzed patients, 2,744 (45.7%) were operated on-pump and 3,262 (54.3%) were operated off-pump. Propensity-matched analysis revealed that patients operated on-pump were more often reoperated due to postoperative bleeding and their in-hospital mortality was higher (6.6% vs 4.5%, p = 0.006 and 8.7% vs 5.8%, p = 0.001, respectively). Long-term all-cause mortality was lower among patients operated off-pump (p = 0.013).ConclusionOn the basis of our findings we suggest that off pump technique should be considered as perfectly acceptable in octogenarians
Underlying Event measurements in pp collisions at and 7 TeV with the ALICE experiment at the LHC
Motor unit fatigability following chronic carnosine supplementation in aged rats
Studies suggest that carnosine (beta-alanyl-L-histidine) is effective in treating neuromuscular diseases associated with aging, but there is still a need to clarify its role in motor units (MUs) function during aging. In this study, 40 male Wistar rats aged 15 months were randomly assigned to a control or to two experimental groups in which 0.1% carnosine supplementation was performed for 10 or 34 weeks. After 34 weeks, we examined fast fatigable (FF), fast fatigue-resistant (FR) and slow (S) MUs' force properties and fatigability, as well as antioxidant potential, advanced glycation end products, activity of enzymes, and histidyl dipeptides content in the medial gastrocnemius muscle. Short- and long-term carnosine supplementation maintained the force of FF MUs at a higher level during its rapid decline seen from the initial 10 to 70 s of the fatigue test. In FF, especially long-term, and in FR MUs, especially short-term, carnosine supplementation resulted in less rapid force decline during the initial 70 s of the second fatigue protocol. Carnosine supplementation did not change muscle antioxidant potential and mortality rate (~35% in all groups), nor muscle mass with aging. Moreover, instead of the expected increase, a decrease in histidyl dipeptides by ~30% in the red portion of medial gastrocnemius muscle after long-term supplementation was found. After chronic carnosine supplementation, the specific changes in fatigue resistance were observed in FF and FR units, but not in S MU types that were not accompanied by an improvement of antioxidant potential and activity of glycolytic or oxidative enzymes in aged rats. These observations indicate that carnosine supplementation during aging may generate different physiological adaptations which should be considered as an important factor when planning treatment strategies
Monosaccharides as Potential Chiral Probes for the Determination of the Absolute Configuration of Secondary Alcohols
Herein, a new method for the elucidation
of the absolute configuration
of chiral secondary alcohols is proposed. This method is an alternative
for a widely used approach reported by Mosher and Dale and similar
methods that are based on the <sup>1</sup>H NMR shift (δ) changes
of protons that are attached to the substituents of the oxymethine
carbon atom. The presented method is not based on tracking the chemical
shift changes and utilizes stereochemically defined monosaccharides
as chiral probes. A secondary alcohol is glycosylated, and the resulting
glycoside is subjected to NMR studies. The observation of dipolar
couplings between the protons of the monosaccharide moiety and the
protons of the secondary alcohol moiety via the NOESY/ROESY spectra
enables the determination of the absolute configuration of the oxymethine
carbon atom
Effects of changes in intracellular iron pool on AlkB-dependent and AlkB-independent mechanisms protecting E.coli cells against mutagenic action of alkylating agent
An Escherichia coli hemH mutant accumulates protoporphyrin IX, causing photosensitivity of cells to visible light. Here, we have shown that intracellular free iron in hemH mutants is double that observed in hemH(+) strain. The aim of this study was to recognize the influence of this increased free iron concentration on AlkB-directed repair of alkylated DNA by analyzing survival and argE3 → Arg(+) reversion induction after λ>320 nm light irradiation and MMS-treatment in E. coli AB1157 hemH and alkB mutants. E.coli AlkB dioxygenase constitutes a direct single-protein repair system using non-hem Fe(II) and cofactors 2-oxoglutarate (2OG) and oxygen (O2) to initiate oxidative dealkylation of DNA/RNA bases. We have established that the frequency of MMS-induced Arg(+) revertants in AB1157 alkB(+)hemH(-)/pMW1 strain was 40 and 26% reduced comparing to the alkB(+)hemH(-) and alkB(+)hemH(+)/pMW1, respectively. It is noteworthy that the effect was observed only when bacteria were irradiated with λ>320 nm light prior MMS-treatment. This finding indicates efficient repair of alkylated DNA in photosensibilized cells in the presence of higher free iron pool and AlkB concentrations. Interestingly, a 31% decrease in the level of Arg(+) reversion was observed in irradiated and MMS-treated hemH(-)alkB(-) cells comparing to the hemH(+)alkB(-) strain. Also, the level of Arg(+) revertants in the irradiated and MMS treated hemH(-) alkB(-) mutant was significantly lower (by 34%) in comparison to the same strain but MMS-treated only. These indicate AlkB-independent repair involving Fe ions and reactive oxygen species. According to our hypothesis it may be caused by non-enzymatic dealkylation of alkylated dNTPs in E. coli cells. In in vitro studies, the absence of AlkB protein in the presence of iron ions allowed etheno(ϵ) dATP and ϵdCTP to spontaneously convert to dAMP and dCMP, respectively. Thus, hemH(-) intra-cellular conditions may favor Fe-dependent dealkylation of modified dNTPs
Understanding the Electronic Factors Responsible for Ligand Spin–Orbit NMR Shielding in Transition-Metal Complexes
The significant role
of relativistic effects in altering the NMR
chemical shifts of light nuclei in heavy-element compounds has been
recognized for a long time; however, full understanding of this phenomenon
in relation to the electronic structure has not been achieved. In
this study, the recently observed qualitative differences between
the platinum and gold compounds in the magnitude and the sign of spin–orbit-induced
(SO) nuclear magnetic shielding at the vicinal light atom (<sup>13</sup>C, <sup>15</sup>N), σ<sup>SO</sup>(LA), are explained by the
contractions of 6s and 6p atomic orbitals in Au complexes, originating
in the larger Au nuclear charge and stronger scalar relativistic effects
in gold complexes. This leads to the chemical activation of metal
6s and 6p atomic orbitals in Au complexes and their larger participation
in bonding with the ligand, which modulates the propagation of metal-induced
SO effects on the NMR signal of the LA via the Spin–Orbit/Fermi
Contact (SO/FC) mechanism. The magnitude of the σ<sup>SO</sup>(LA) in these square-planar complexes can be understood on the basis
of a balance between various metal-based 5d → 5d* and 6p →
6p* orbital magnetic couplings. The large and positive σ<sup>SO</sup>(LA) in platinum complexes is dominated by the shielding
platinum-based 5d → 5d* magnetic couplings, whereas small or
negative σ<sup>SO</sup>(LA) in gold complexes is related to
the deshielding contribution of the gold-based 6p → 6p* magnetic
couplings. Further, it is demonstrated that σ<sup>SO</sup>(LA)
correlates quantitatively with the extent of M–LA electron
sharing that is the covalence of the M–LA bond (characterized
by the QTAIM delocalization index, DI). The present findings will
contribute to further understanding of the origin and propagation
of the relativistic effects influencing the experimental NMR parameters
in heavy-element systems
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